SRS Labs Stereo Amplifier Lock In Amplifier User Manual

MODEL SR530

LOCK-IN AMPLIFIER

1290-D Reamwood Avenue

Sunnyvale, CA 94089 U.S.A.

Phone: (408) 744-9040 • Fax: (408) 744-9049

Email: [email protected] • www.thinkSRS.com

Stanford Research Systems, Inc.

Rev. 2.3 (06/2005)

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Table of Contents

Condensed Information

SAFETY and Preparation for use

Symbols

Guide to Programming

Communications

Command Syntax

Status LED's

RS232 Echo Feature

Try-out with an ASCII Terminal

Specifications

Front Panel Summary

Abridged Command List

Status Byte Definition

Configuration Switches

Command List

Status Byte

Errors

Reset Command

Trouble-Shooting Interface Problems

Common Hardware Problems

Common Software Problems

Guide to Operation

Front Panel

Signal Inputs

Signal Filters

Sensitivity

Dynamic Reserve

Status Indicators

Display Select

Channel 1 Display

R Output

RS232 Interface

Introduction to the RS232

Data Communications Equipment

Wait Command

Termination Sequence

Output Channel 1

Rel Channel 1

Offset Channel 1

Expand Channel 1

X (RCOSØ) Output

Channel 2 Display

Ø Output

Output Channel 2

Rel Channel 2

Auto Phase

Offset Channel 2

Expand Channel 2

Y (RSINØ) Output

Reference Input

Trigger Level

Reference Mode

Reference Display

Phase Controls

Time Constants

Noise Measurements

Power Switch

GPIB (IEEE-488) Interface

Introduction to the GPIB

GPIB Capabilities

Response to Special GPIB commands

Serial Polls and SRQ's

Echo Mode using the RS232

Using Both the RS232 & GPIB

Lock-in Technique

Introduction to Lock-in Amplifiers

Measurement Example

Understanding the Specifications

Shielding and Ground Loops

Dynamic Reserve

Current Inputs

Bandpass Filter

Notch Filters

Frequency Range

Output Time Constants

Noise Measurements

Ratio Capability

Computer Interfaces

Internal Oscillator

Local/Remote Operation

Default Settings

Rear Panel

AC Power

GPIB (IEEE-488) Connector

RS232 Connector

Signal Monitor Output

Pre-Amp Connector

A/D Inputs and D/A Outputs

Ratio Feature

SR530 Block Diagram

Block Diagram

Signal Channel

Reference Channel

Phase-Sensitive Detector

DC Amplifier and System Gain

Microprocessor System

Internal Oscillator

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IBM PC, Microsoft Basic, via GPIB

HP-85, HP Basic, via HPIB

Circuit Description

Introduction

Signal Amplifier

Current Amplifier

Notch Filters

Bandpass Filter

Reference Oscillator

PSD, LP Filters and DC Amplifier

Analog Output

A/D's

D/A's

Expand

Front Panel

Microprocessor Control

RS232 Interface

GPIB Interface

Power Supplies

Internal Oscillator

Documentation

Parts List, Oscillator Board

Parts List, Main Board

Parts List, Front Panel Board

Parts List, Quad Board

Parts List, Miscellaneous

Schematic Diagrams

Calibration and Repair

Introduction

Multiplier Adjustments

Amplifier and Filter Adjustments

CMRR Adjustment

Line Notch Filter Adjustment

2xLine Notch Filter Adjustment

Repairing Damaged Front-End

Appendix A: Noise Sources and Cures

Johnson Noise

'1/f' Noise

Noise Spectrum

Capacitive Coupling

Inductive Coupling

Ground Loops

Microphonics

Thermocouple Effect

Appendix B: RS232

Simplest Case Using the RS232

Using Control Lines

Baud Rates

Stop Bits

Parity

Voltage Levels

'Eavesdropping'

Appendix C: GPIB

Introduction to the GPIB

Bus Description

Appendix D: Program Examples

Program Description

IBM PC, Microsoft Basic, via RS232

IBM PC, Microsoft Fortran, via RS232

IBM PC, Microsoft C, via RS232

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Safety and Preparation for Use

***CAUTION***: This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set for

the wrong applied ac input-source voltage or if the wrong fuse is installed.

LINE VOLTAGE SELECTION

FURNISHED ACCESSORIES

The SR530 operates from a 100V, 120V, 220V, or

240V nominal ac power source having a line

frequency of 50 or 60 Hz. Before connecting the

power cord to a power source, verify that the LINE

VOLTAGE SELECTOR card, located in the rear

panel fuse holder, is set so that the correct ac input

voltage value is visible.

- Power Cord

- Operating Manual

ENVIRONMENTAL CONDITIONS

OPERATING

Temperature: +10° C to +40° C

(Specifications apply over +18° C to +28° C)

Relative Humidity: < 90% Non-condensing

Conversion to other ac input voltages requires a

change in the fuse holder voltage card position and

fuse value. Disconnect the power cord, open the

fuse holder cover door and rotate the fuse-pull lever

to remove the fuse. Remove the small printed circuit

board and select the operating voltage by orienting

the printed circuit board to position the desired

voltage to be visible when pushed firmly into its slot.

Rotate the fuse-pull lever back into its normal

position and insert the correct fuse into the fuse

holder.

NON-OPERATING

Temperature: -25° C to 65° C

Humidity: < 95% Non-condensig

OPERATE WITH COVERS IN PLACE

To avoid personal injury, do not remove the

product covers or panels. Do not operate the

product without all covers and panels in place.

LINE FUSE

Verify that the correct line fuse is installed before

connecting the line cord. For 100V and 120V, use a

½ Amp fuse and for 220V and 240V, use a 1/4 Amp

fuse.

WARNING REGARDING USE WITH

PHOTOMULTIPLIERS

It is relatively easy to damage the signal inputs if

a photomultiplier is used improperly with the

lock-in amplifier. When left completely

unterminated, a PMT will charge a cable to a

few hundred volts in a very short time. If this

cable is connected to the lockin, the stored

charge may damage the front-end transistors.

To avoid this problem, provide a leakage path of

about 100 KΩ to ground inside the base of the

PMT to prevent charge accumulation.

LINE CORD

This instrument has a detachable, three-wire power

cord with a three-contact plug for connection to both

the power source and protective ground. The

protective ground contact connects to the accessible

metal parts of the instrument. To prevent electrical

shock, always use a power source outlet that has a

properly grounded protective-ground contact.

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SR530 Specification Summary

General

Power

100, 120, 220, 240 VAC (50/60 Hz); 35 Watts Max

Mechanical

Warranty

17" x 17" x 5.25" (Rack Mount Included) 16 lbs.

Two years parts and labor.

Signal Channel

Inputs

Voltage:

Current:

Voltage:

Current:

Voltage:

Current:

Voltage:

Single-ended or True Differential

10⁶Volts/Amp

Impedance

100 MΩ + 25 pF, ac coupled

1 kΩ to virtual ground

Full Scale Sensitivity

Maximum Inputs

100 nV (10 nV on expand) to 500 mV

100 fA to 0.5 µA

100 VDC, 10 VAC damage threshold

2 VAC peak-to-peak saturation

10 mA damage threshold

Current:

1 µA ac peak-to-peak saturation

7 nV/√Hz at 1 kHz

0.13 pA/√ Hz at 1 kHz

Noise

Voltage:

Current:

Range:

Common Mode

1 Volt peak; Rejection: 100 dB dc to 1KHz

Above 1KHz the CMRR degrades by 6 dB/Octave

Gain Accuracy

Gain Stability

Signal Filters

1% (2 Hz to 100KHz)

200 ppm/°C

60 Hz notch, -50 dB (Q=10, adjustable from 45 to 65 Hz)

120 Hz notch, -50 dB (Q=10, adjustable from 100 to 130 Hz))

Tracking bandpass set to within 1% of ref freq (Q=5)

20 dB LOW (1 µV to 500 mV sensitivity)

40 dB NORM (100 nV to 50 mV sensitivity)

60 dB HIGH (100 nV to 5 mV sensitivity)

Bandpass filter adds 20 dB to dynamic reserve

Line Notch filters increase dynamic reserve to 100 dB

Dynamic Reserve

Reference Channel

Frequency

Input Impedance

Trigger

0.5 Hz to 100 kHz

1 MΩ, ac coupled

SINE:

100 mV minimum, 1Vrms nominal

PULSE:

±1 Volt, 1 µsec minimum width

Mode

Fundamental (f) or 2nd Harmonic (2f)

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Acquisition Time

25 Sec at 1 Hz

6 Sec at 10 Hz

2 Sec at 10 kHz

Slew Rate

1 decade per 10 S at 1 kHz

90° shifts

Phase Control

Fine shifts in 0.025° steps

0.01° rms at 1 kHz, 100 msec, 12 dB TC

0.1°/°C

Phase Noise

Phase Drift

Phase Error

Orthogonality

Less than 1° above 10Hz

90° ± 1°

Demodulator

Stability

5 ppm/°C on LOW dynamic reserve

50 ppm/°C on NORM dynamic reserve

500 ppm/°C on HIGH dynamic reserve

Time Constants

Offset

Pre:

1msec to 100 sec (6 dB/Octave)

Post: 1sec, 0.1 sec, none (6 dB/Octave) or none

Up to 1X full scale (10X on expand)

Both channels may be offset

Harmonic Rej

Outputs & Interfaces

-55 dB (bandpass filter in)

Channel 1 Outputs

Channel 2 Outputs

Output Meters

Output LCD's

Output BNC's

X Output

X (RcosØ), X Offset, R (magnitude), R Offset, X Noise, X5 (external D/A)

Y (RsinØ), Y Offset, Ø (phase shift of signal), Y Noise, X6 (external D/A)

2% Precision mirrored analog meter

Four digit auto-ranging LCD display shows same values as the analog meters

±10 V output corresponds to full scale input, <1Ω output impedance

X (RcosØ), ±10 V full scale, < 1Ω output impedance

Y Output

Y (RsinØ), ±10 V full scale, < 1Ω output impedance

Reference LCD

RS232

Four digit LCD display for reference phase shift or frequency

Interface controls all functions. Baud rates from 300 to 19.2 K

Interface controls all functions. ( IEEE-488 Std )

GPIB

A/D

4 BNC inputs with 13 bit resolution (±10.24 V)

D/A

2 BNC outputs with 13 bit resolution (±10.24 V)

Ratio

Ratio output equals 10X Channel 1 output divided by the Denominator input.

Internal Oscillator

Range:

1 Hz to 100 kHz, 1% accuracy

150 ppm/°C

Stability:

Distortion: 2% THD

Amplitude: 1% accuracy, 500 ppm/°C stability

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Front Panel Summary

Signal Inputs

Signal Filters

Single Ended (A), True Differential (A-B), or Current (I)

Bandpass:

Line Notch:

Q-of-5 Auto-tracking filter (In or Out)

Q-of-10 Notch Filter at line frequency (In or Out)

2XLine Notch: Q-of-10 Notch Filter at twice line frequency (In or Out)

Sensitivity

Full scale sensitivity from 100 nV to 500 mV RMS for voltage inputs

or from 100 fA to 500 nA RMS for current inputs.

Dynamic Reserve Select Dynamic Reserve Stability

Sensitivity Ranges

1 µV to 500 mV

100 nV to 50 mV

100 nV to 5 mV

LOW

20 dB

40 dB

60 dB

5 ppm

NORM

HIGH

50 ppm

500 ppm

Status Indicators

Display Select

OVLD Signal Overload

UNLK PLL is not locked to the reference input

ERR

ACT

Illegal or Unrecognized command

RS232 or GPIB interface Activity

REM Remote mode: front panel has been locked-out

Channel 1

X (RcosØ)

X Offset

Channel 2

Y (RsinØ)

Y Offset

R (Magnitude) Ø (Phase)

R Offset

X Noise

X5 (D/A)

Ø (no offset)

Y Noise

X6 (D/A)

Analog Meters

Output LCD's

Output BNC's

Expand

Displays Channel 1 and 2 Outputs as a fraction of full scale

Displays the Channel 1 and 2 Outputs in absolute units

Channel 1 and 2 Outputs follow Analog Meters, ± 10 V for ± full scale

Multiplies the Channel 1 or 2 Analog Meter and Output voltage by a factor X1 or X10.

REL

Set the Channel 1 or 2 Offset to null the output: subsequent readings are relative

readings. REL with phase display performs auto-phasing. REL with X5, X6 display

zeroes the D/A outputs.

Offset

Enables or Disables Offset, and allows any offset (up to full scale) to be entered. X, Y,

and R may be offset and X5, X6 may be adjusted. Phase is offset using the reference

phase shift.

X BNC

X (RcosØ) output, ± 10V full scale

Y BNC

Y (RsinØ) output, ± 10V full scale

Reference Input

1 MΩ Input, 0.5 Hz to 100 KHz, 100 mV minimum

Reference Trigger Trigger on rising edge, zero crossing, or falling edge

f/2f Mode

PLL can lock to either X1 or X2 of the reference input frequency

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Phase Controls

Adjust phase in smoothly accelerating 0.025° steps, or by

90° steps. Press both 90° buttons to zero the phase.

Reference LCD

Time Constants

Display reference phase setting or reference frequency

Pre-filter has time constants from 1 mS to 100 S (6 dB/Octave)

Post-filter has time constants of 0, 0.1 or 1.0 S (6 dB/Octave)

ENBW

Equivalent Noise Bandwidth. Specifies the bandwidth when making

Noise measurements. (1Hz or 10 Hz ENBW)

Power Switch

Instrument settings from the last use are recalled on power-up

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Abridged Command List

Return X Offset Status

Turn off X Offset

Turn on X Offset, v = offset

Return Y Offset Status

Turn off Y Offset

Turn on Y Offset, v = offset

Return R Offset Status

Turn off R Offset

OX 0

OX 1,v

OY 0

OY 1,v

Auto offset X

Auto offset Y

Auto offset R

Auto phase

Return Bandpass Filter Status

Take out the Bandpass Filter

Put in the Bandpass Filter

OR 0

OR 1,v

Turn on R Offset, v = offset

Return the Phase Setting

Set the Phase to v. Abs(v) <999 deg

Return the Reference LCD Status

Display the Reference Frequency

Display the Reference Phase Shift

Return the Channel 1 output

Return the Channel 2 output

Return the X Output

Return Dynamic Reserve Setting

Set DR to LOW range

Set DR to NORM range

Set DR to HIGH range

Return the Y Output

Return the trigger mode

Set the trigger for rising edge

Set the trigger for + zero crossing

Set the trigger for falling edge

Return Channel n (1 or 2) Expand

Status

Turn Channel n Expand off

Turn Channel n Expand on

En,0

En,1

Return the display status

Display X and Y

Display X and Y Offsets

Display R and Ø

Display R Offset and Ø

Display X and Y noise

Display X5 and X6 (ext D/A)

Return the Reference Frequency

...

Return the Sensitivity Setting

Select 10 nV Full-Scale

(G1-G3 with SRS preamp only)

Select 500 mV Full-Scale

G24

Return Preamp Status (1=installed)

Return pre-filter setting

T1,1

...

T1,11

Set the pre-filter TC to 1 mS

Return the Remote/Local Status

Select Local: Front panel active

Select Remote: Front panel inactive

Select Remote with full lock-out

Set the pre-filter TC to 100 S

Return the post-filter setting

Remove post filter

Set the post filter TC to 0.1 S

Set the post filter TC to 1.0 S

T2,0

T2,1

T2,2

Set RS232 End-of-Record to <cr>

Set End-of-record to n,m,o,p

Jn,m,o,p

...

K32

Simulates Key-press of button #1

(see un-abridged command list)

Simulates Key-press of button #32

Return the value of the SRQ mask

Set the SRQ Mask to the value n

(See the Status Byte definition)

L1,0

L1,1

Return Status of Line Notch Filter

Remove Line Notch Filter

Insert Line Notch Filter

Return the RS232 wait interval

Set RS232 wait interval to nX4mS

Return the voltage at the rear panel

analog port n. (n from 1 to 6)

L2,0

L2,1

Return Status of 2XLine Filter

Remove 2XLine Notch Filter

Insert 2XLine Notch Filter

X5,v

X6,v

Set analog port 5 to voltage v

Set analog port 6 to voltage v

Return the f/2f Status

Set reference mode to f

Set reference mode to 2f

Return the Status Byte value

Test bit n of the Status Byte

Return the ENBW setting

Select 1 Hz ENBW

Select 10 Hz ENBW

Reset to default settings and cancel

all pending commands.

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Status Byte Definition

Bit Meaning

0 Magnitude too small to calculate

phase

1 Command Parameter is out-of-range

2 No detectable reference input

3 PLL is not locked to the reference

4 Signal Overload

5 Auto-offset failed: signal too large

6 SRQ generated

7 Unrecognized or illegal command

Configuration Switches

There are two banks of 8 switches, SW1 and

SW2, located on the rear panel. SW1 sets the

GPIB address and SW2 sets the RS232

parameters. The configuration switches are read

continuously and any changes will be effective

immediately.

SW2:RS232 Mode Switches

Bit 1

Bit 2

Bit 3

Baud Rate

19200

9600

4800

2400

down up

down down up

up up

down up

SW1:GPIB Mode Switches

down 1200

down 600

down down 300

Bit Example

Function

1 } up

2 } up

3 } up

4 } down

5 } up

GPIB Address Switches

Address 0 to 30 allowed

'up' for bit = 1

'down' for bit = 0

(Most Significant Bit)

Bit

Setting

Explanation

down

Odd parity

Even parity

down

'down' to echo on RS232

(normally 'up')

down

No parity

Parity enabled

Not Used

down

No echo (for computer)

Echo mode (for terminal)

If the GPIB mode switches are set as shown in the

example column above, then the lockin will be

addressed as GPIB device #23, and all GPIB

commands and data will be echoed over the

RS232 for de-bugging purposes.

down

Two stop bits

One stop bit

unused

Eight data bits are always sent, regardless of the

parity setting. The most significant bit is always

zero.

Example: Bit 1 'down' and all others 'up' for

RS232 communication at 9600 baud, no parity,

two stop bits, and no echo or prompts by the

SR530.

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allowable signals at the inputs. The notch

frequencies are set at the factory to either 50 Hz

or 60 Hz. The user can adjust these frequencies.

(See the Maintenance and Repair section for

alignment details.) These filters precede the

bandpass filter in the signal amplifier.

SR510 Guide to Operation

Front Panel

The front panel has been designed to be almost

self-explanatory. The effect of each keypress is

usually reflected in the change of a nearby LED

indicator or by a change in the quantity shown on

a digital display. This discussion explains each

section of the front panel, proceeding left to right.

The bandpass filter has a Q of 5 and a 6 dB roll off

in either direction. Thus, the pass band (between

70% pass points) is always equal to 1/5th of the

center frequency. The center frequency is

continually adjusted to be equal to the internal

demodulator frequency. When the reference

mode is f, the filter tracks the reference. When the

mode is 2f, the filter frequency is twice the

reference input frequency. The center frequency

tracks as fast as the reference oscillator can slew

and may be used during frequency scans. The

bandpass filter adds up to 20 dB of dynamic

reserve for noise signals outside the pass band,

and increases the harmonic rejection by at least

13dB. (2nd harmonic attenuated by 13 dB, higher

harmonics attenuated 6dB/octave more.) If not

needed to improve the dynamic reserve or the

harmonic rejection then the filter should be left

OUT.

Signal Inputs

There are three input connectors located in the

SIGNAL INPUT section of the front panel. The

rocker switch located above the B input selects

the input mode, either single-ended, A, differential,

A-B, or current, I.

The A and B inputs are voltage inputs with 100

MΩ, 25 pF input impedance. Their connector

shields are isolated from the chassis ground by

10Ω. These inputs are protected to 100V dc but

the ac input should never exceed 10V peak. The

maximum ac input before overload is 1V peak.

Sensitivity

The I input is a current input with an input

impedance of 1 KΩ to a virtual ground. The

largest allowable dc current before overload is 1

µA. No current larger than 10 mA should ever be

The sensitivity is displayed as a value (1-500) and

a scale (nV, µV, mV). When using the current

input, which has a gain of 10 V/A, these scales

applied to this input. The conversion ratio is 10

read fA, pA, and nA. The two keys in the

SENSITIVITY section move the sensitivity up and

down. If either key is held down, the sensitivity will

continue to change in the desired direction four

times a second.

V/A, thus, the full scale current sensitivities range

from 100 fA to 500 nA with a max ac input before

overload of 1 µA peak. You should use short

cables when using the current input.

The full scale sensitivity can range from 100 nV to

500 mV. The sensitivity indication is not changed

by the EXPAND function. The EXPAND function

increases the output sensitivity (Volts out /volts in)

as well as the resolution of the digital output

display.

Signal Filters

There are three user selectable signal filters

available; a line frequency notch, a 2X line

frequency notch, and an auto-tracking bandpass.

Each of the filters has a pair of indicator LED's and

a function key located in the SIGNAL FILTERS

section of the front panel. Pressing a key will

toggle the status of the appropriate filter. The

status of each filter is displayed as IN, filter active,

or OUT, filter inactive.

Not all dynamic reserves are available at all

sensitivities. If the sensitivity is changed to a

setting for which the dynamic reserve is not

allowed, the dynamic reserve will change to the

next setting which is allowed. Sensitivity takes

precedence over the dynamic reserve. The

sensitivity range of each dynamic reserve is

shown below.

The notch filters have a Q of 10 and a depth of at

least 50 dB. Thus, the line frequency notch is 6

Hz wide and the 2X line notch has a width of 12

Hz. Both of these filters can increase the dynamic

reserve up to 50 dB at the notch frequencies. The

achievable reserve is limited by the maximum

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Dynamic Reserve

Sensitivity Range

the output, i.e. in the ac amplifier or output time

constant. In this case, the dynamic reserve,

sensitivity, time constant, or ENBW needs to be

adjusted.

LOW

NORM

HIGH

1 µV through 500 mV

100 nV through 50 mV

100 nV through 5 mV

UNLK indicates that the reference oscillator is not

phase locked to the external reference input. This

can occur if the reference amplitude is too low, the

frequency is out of range, or the trigger mode is

incorrect for the reference signal waveform.

Dynamic Reserve

The dynamic reserve (DR) is set using the keys in

the DYNAMIC RESERVE section. The reserve is

displayed by the three indicator LED's, HIGH,

NORM, LOW. Only those dynamic reserve

settings available for the sensitivity are allowed

(see above table). For example, when the

ERR flashes when an error occurs on one of the

computer interfaces, such as an incorrect

command, invalid parameter, etc.

sensitivity is 500 mV, the DR will always be LOW.

ACT indicates activity on the computer interfaces.

This LED blinks every time a character is received

or transmitted by the SR530.

The dynamic reserve and output stability of each

setting are shown below.

REM indicates that the unit is in the remote state

and that the front panel controls are not operative.

There are two remote states. The Remote-With-

Lockout will not allow any inputs from the front

panel. The Remote-Without-Lockout command

allows you to return the front panel to operation by

pressing the LOCAL key.

Setting Dynamic Reserve Output Stability

(ppm/°C)

LOW

NORM

HIGH

20 dB

40 dB

60 dB

500

Since a higher DR results in degraded output

stability, you should use the lowest DR setting for

which there is no overload indication. Note that

using the Bandpass Filter provides about 20dB of

additional DR and so allows you to operate with a

lower DR setting.

Display Select

The keys in the DISPLAY section select the

parameters to be displayed on the OUTPUT

METERS and the output of the two OUTPUT BNC

connectors. The displayed parameters are

indicated by one of the six DISPLAY LED's and

can be either the two demodulator outputs (X Y),

the demodulator output offsets (X OFST Y OFST),

the magnitude and phase (R Ø), the magnitude

offset and phase (R OFST Ø), the rms noise on X

and Y (X NOISE Y NOISE), or the D/A outputs (X5

D/A X6). When displaying NOISE, the equivalent

noise bandwidth is selected in the TIME

CONSTANT section. When displaying D/A, the 2

outputs are the X5 and X6 rear panel D/A outputs,

allowing the D/A outputs to be set from the front

panel. This feature can be used to set the

reference frequency when using the internal

oscillator.

Status

There are five STATUS LED's.

OVLD indicates a signal overload. This condition

can occur when the signal is too large, the

sensitivity is too high, the dynamic reserve is too

low, the offset is on, the expand is on, the time

constant is not large enough, or the ENBW is too

large.

The OVLD LED blinks four times a second when

an output is overloaded. This occurs if an output

exceeds full scale. For example, during a

quadrature measurement where X exceeds full

scale while Y is near zero, a blinking OVLD

indicates that it is safe to take data from the Y

output since only the X output is overloaded. The

signal path to the Y output is not overloaded.

OVLD also blinks if a noise measurement is

attempted on an output which exceeds full scale.

Channel 1 Display

The channel 1 outputs are summarized below. X

is equal to RcosØ where Ø is the phase shift of

the signal relative to the reference oscillator of the

lock-in.

If the OVLD LED is on continuously or flashes

randomly, then an overload has occurred before

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display CH1

setting output expand? offset? (RCOSØ)

The left hand analog meter always displays the

CHANNEL 1 OUTPUT voltage. Accuracy is 2% of

full scale.

X+X

yes

X+X

ofst

The CHANNEL 1 LCD display provides a read-out

of the displayed parameter in real units. The scale

of the displayed quantity is indicated by the three

scale LED's to the left of the display. This read-

out auto ranges and will reflect the sensitivity

added when the EXPAND function is on. When

displaying X5, the scale LED's are off and the

units are volts.

XOFST

ofst

R+R

X+X

ofst

R OFST R

X+X

ofst

(enbw)

XNOISE X noise yes

X+X

ofst

X5 X5 no

adjust X+X

ofst

The EXPAND and OFFSET conditions for each

display are retained when the DISPLAY is

changed. Thus, when the DISPLAY is changed

from X to R, the EXPAND and OFFSET assume

the conditions set the last time the DISPLAY was

R. If the DISPLAY is changed back to X, the

EXPAND and OFFSET return to conditions set for

Rel Channel 1

Every time the REL key is pressed, the displayed

parameter is offset to zero. This is done by

loading the displayed parameter's offset with

minus one times the present output. If the output

is greater than 1.024 times full scale, the REL

function will not be able to zero the output. In this

case, the OFFSET ON LED will blink and the

offset value will be set to its maximum value.

R Output

The magnitude, R, is given by the equation:

The REL function and the manual OFFSET are

both ways to enter the offset value. After using

the REL key, the offset may be adjusted using the

manual OFFSET.

2 1/2

) }

ofst

R = {(X+X

) + (Y+Y

+ R

ofst

Note that the X and Y offsets affect the value of R

while the X and Y expands do not.

When the DISPLAY is X, X OFST, or X NOISE,

the REL key sets the X OFFSET (which affects

the X (RCOSØ) output). If X NOISE is being

displayed, the REL function zeroes X and the

noise output will require a few seconds to settle

again.

The magnitude output has a resolution of 12 bits

plus sign and is updated every 3.5 mS. To

achieve maximum accuracy, the magnitude should

be as large a fraction of full scale as possible.

R is expanded after the calculation. Thus, when R

is expanded, the full scale resolution drops by a

factor of 10 to about 9 bits.

When the DISPLAY is R or R OFST, the REL key

sets the R OFFSET.

The REL key zeroes the X5 output when the

DISPLAY is D/A.

Output Channel 1

The CHANNEL 1 output is available at the left

hand OUTPUT BNC connector. The output

parameter is selected by the DISPLAY setting and

can be X, X OFST, R (magnitude), R OFST, X

NOISE, or X5 (external D/A). (Note that X5 is the

ratio output at power up. When displaying X5, the

ratio output is 10R/X1). All outputs are 10V full

scale when the EXPAND is off. With the EXPAND

on, the output is multipled by 10 effectively

Offset Channel 1

The OFFSET buttons control the manual offset.

The offset is turned ON and OFF using the upper

key in the OFFSET section. When the offset is

ON, the lower two keys are used to set the amount

of offset. A single key press will advance the

offset by 0.025% of full scale. If the key is held

down, the offset advances in larger and larger

increments, the largest increment being 10% of full

scale. When the offset is turned OFF the applied

offset returns to zero but the offset value is not

lost. The next press of the upper offset key (return

increasing the full scale sensitivity by 10. (X5 may

not be expanded). The output impedance is < 1Ω

and the output current is limited to 20 mA.

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in magnitude to the selected sensitivity which is in

phase with the reference oscillator will generate a

10V output. The output impedance is <1Ω and the

output current is limited to 20 mA.

to ON) sets the offset to the previously entered

value.

If an attempt is made to advance the offset value

beyond full scale, the ON LED will blink. An offset

up to 1.024 times the full scale sensitivity may be

entered. When the EXPAND is on, this is 10X the

full scale output.

The X (RCOSØ) output is affected by the X offset

but may not be expanded. The X (RCOSØ) is not

affected by the DISPLAY setting except for two

cases. When the DISPLAY is set to X OFST, the

X (RCOSØ) output is the X offset. When the

DISPLAY is set to X NOISE, the X (RCOSØ)

output has a bandwidth equal to the ENBW (1 or

10 Hz) instead of the time constant.

Note that the offsets (either manual offset or those

generated by the REL function) represent a

fraction of the full scale reading, and so their

absolute value will change when the sensitivity

scale is changed. A signal which has been nulled

by an offset will not be nulled when the sensitivity

scale is changed. The analog meter and the

output BNC indicate the same value given by the

equation:

Channel 2 Display

The channel 2 outputs are summarized below. Y

is equal to RsinØ where Ø is the phase shift of the

signal relative to the reference oscillator of the

lock-in.

= 10A (A V cosØ+V ) {if the output is X}

v i os

out

where...

display CH2

setting output expand? offset? (RSINØ)

= 1 or 10 per the Expand

= 1/Sensitivity

Y+Y

yes yes

Y+Y

ofst

= magnitude of the signal

YOFST

ofst

= phase between signal & reference

= offset (fraction of FS < 1.024)

Phase

Y+Y

ofst

Phase

Y+Y

ofst

YNOISE Y noise

X6 X6

yes yes

Y+Y

(enbw)

When the DISPLAY is X, X OFST, or X NOISE,

the OFFSET keys adjust the X OFFSET (which

affects the X (RCOSØ) output). When the

DISPLAY is R or R OFST, the OFFSET keys

adjust the R OFFSET. When the DISPLAY is X5,

the OFFSET up and down keys set the output

voltage of D/A output X5 (also on the rear panel)

up to ±10.24 V. Adjusting X5 will cancel the

RATIO output.

adjust Y+Y

The EXPAND and OFFSET conditions for each

display are retained when the DISPLAY is

changed. Thus, when the DISPLAY is changed

from Y to Ø, the EXPAND and OFFSET turn off. If

the DISPLAY is changed back to Y the EXPAND

and OFFSET return to conditions set for Y.

Ø Output

Expand Channel 1

The phase, Ø, is given by the equation:

-1

The output EXPAND is toggled by pressing the

key in the Channel 1 EXPAND section. The

expand status is indicated by the X10, expand on,

and the X1, expand off, LED's. Only the Channel

1 OUTPUT is affected, the X (RCOSØ) output is

not expanded.

Ø = - tan {(Y+Y

)/(X+X

)}

ofst

Note that the X and Y offsets affect the value of Ø

while the X and Y expands do not.

The X5 D/A output may not be expanded.

The Phase Output voltage is 50 mV per degree

with a resolution of 2.5 mV or 1/20 of a degree.

The output range is from -180 to +180 degrees.

The phase output is updated every 3.5 mS. To

achieve maximum accuracy, the magnitude, R,

should be as large a fraction of full scale as

X (RCOSØ) Output

The analog output, X+X

, is available at the X

(RCOSØ) BNC connector. An input signal equal

ofst

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possible. If R is less than 0.5% of full scale, the

phase output defaults to zero degrees.

The CHANNEL 2 LCD display provides a read-out

of the displayed parameter in real units. The scale

of the displayed quantity is indicated by the four

scale LED's to the right of the display. This read-

out auto ranges and will reflect the sensitivity

added when the EXPAND function is on. When

displaying X6, the scale LED's are off and the

units are volts.

The Phase Output may not be expanded and the

OFFSET keys do not offset the Phase Output.

However, the Phase Output can be offset using

the Reference Phase shift.

The Reference Phase shift, which may be

adjusted via the phase controls in the reference

section, rotates the lock-in's internal coordinate

axes relative to the reference input. The Phase

Output is the phase difference between the signal

and the lock-in's coordinate system. For example,

if a signal exactly in phase with the reference input

is being measured and the Reference Phase shift

is zero, the Phase Output will be zero also. This is

because the lock-in coordinate system is in phase

with the reference input and signal. If the

Reference Phase shift is set to +45 degrees, then

the lock-in coordinate system rotates to +45

degrees from the reference input. Thus, the

reference input is now at -45 degrees from the

lock-in coordinate axes. Since the reference and

signal are in phase, the signal is now at -45

degrees with respect to the lock-in coordinates

and the Phase Output will be -45 degrees.

Rel Channel 2

Every time the REL key is pressed, the displayed

parameter is offset to zero. This is done by

loading the displayed parameter's offset with

minus one times the present output. If the output

is greater than 1.024 times full scale, the REL

function will not be able to zero the output. In this

case, the OFFSET ON LED will blink and the

offset value will be set to its maximum value.

The REL function and the manual OFFSET are

both ways to enter the offset value. After using

the REL key, the offset may be adjusted using the

manual OFFSET.

When the DISPLAY is Y, Y OFST, or Y NOISE,

the REL key sets the Y OFFSET (which affects

the Y (RSINØ) output). If Y NOISE is being

displayed, the REL function zeroes Y and the

noise output will require a few seconds to settle

again.

The sum of the Reference Phase shift and the

Phase Output is the absolute phase difference

between the signal and the reference input.

Therefore, the Phase Output may be offset to zero

by adjusting the Reference Phase shift. This is

sometimes necessary when the Phase Output is

near 180 degrees and varies between +180 and -

180 degrees.

The REL key zeroes the X6 output when the

DISPLAY is D/A.

Auto Phase

Output Channel 2

When the DISPLAY is Ø (phase), the REL key

sets the Reference Phase Shift to the absolute

phase difference between the signal and the

reference. This is done by setting the Reference

Phase Shift to the sum of the Reference Phase

Shift and the present Phase Output. After auto-

phase is performed, the Ø output will be 0 deg, R

will be unchanged, X will be maximized, and Y will

be minimized.

The CHANNEL 2 output is available at the right

hand OUTPUT BNC connector. The output

parameter is selected by the DISPLAY setting and

can be Y, Y OFST, Ø (phase), Ø (phase), Y

NOISE, or X6 (ext D/A). All outputs are ±10V full

scale when the EXPAND is off. With the EXPAND

on, the output is multipled by 10, effectively

increasing the full scale sensitivity by 10. (Ø and

X6 may not be expanded). The Ø (phase) output

is 50 mV/deg (20 deg per Volt) up to ±9 V (±180

deg). The output impedance is <1Ω and the

output current is limited to 20 mA.

Offset Channel 2

The OFFSET section controls the manual offset.

The offset is turned ON and OFF using the upper

key in the OFFSET section. When the offset is

ON, the lower two keys are used to set the amount

of offset. A single key press will advance the

offset by 0.025% of full scale. If the key is held

The right hand analog meter always displays the

CHANNEL 2 OUTPUT voltage. Accuracy is 2% of

full scale.

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down, the offset advances in larger and larger

increments, the largest increment being 10% of full

scale. When the offset is turned OFF the applied

offset returns to zero but the offset value is not

lost. The next press of the upper offset key (return

to ON) sets the offset to the previously entered

value.

Y (RSINØ) Output

The analog output, Y+Y

, is available at the Y

ofst

(RSINØ) BNC connector. An input signal equal in

magnitude to the selected sensitivity which is 90°

out of phase with the reference oscillator will

generate a 10V output. The output impedance is

<1Ω and the output current is limited to 20 mA.

If an attempt is made to advance the offset value

beyond full scale, the ON LED will blink. An offset

up to 1.024 times the full-scale sensitivity may be

entered. When the EXPAND is on, this is 10X the

full scale output.

The Y (RSINØ) output is affected by the Y offset

but may not be expanded. The Y (RSINØ) is not

affected by the DISPLAY setting except for two

cases. When the DISPLAY is set to Y OFST, the

Y (RSINØ) output is the Y offset. When the

DISPLAY is set to Y NOISE, the Y (RSINØ) output

has a bandwidth equal to the ENBW (1 or 10 Hz)

instead of the time constant.

Note that the offsets (either manual offset or those

generated by the REL function) represent a

fraction of the full scale reading, and so their

absolute value will change when the sensitivity

scale is changed. A signal which has been nulled

by an offset will not be nulled when the sensitivity

scale is changed. The analog meter and the

output BNC indicate the same value given by the

equation:

Reference Input

The REFERENCE INPUT BNC is located in

REFERENCE INPUT section. The input is ac

coupled and the impedance is 1 MΩ. The dc

voltage at this input should not exceed 100 V and

the largest ac signal should be less than 10 V

peak.

= 10A (A V sinØ+V ) {if the output is Y}

v i os

out

where...

= 1 or 10 per the Expand

= 1/Sensitivity

Trigger Level

= magnitude of the signal

= phase between signal & reference

= offset (fraction of FS < 1.024)

The TRIGGER MODE indicator toggles from

POSITIVE to SYMMETRIC to NEGATIVE when

the TRIGGER MODE key is pressed.

When the DISPLAY is Y, Y OFST, or Y NOISE,

the OFFSET keys adjust the Y OFFSET (which

affects the Y (RSINØ) output). When the

DISPLAY is Ø, the OFFSET keys do nothing.

When the DISPLAY is X6, the OFFSET up and

down keys set the output voltage of D/A output X6

(also on the rear panel) up to ±10.24V.

If the center TRIGGER MODE LED is on, the

mode is SYMMETRIC and the reference oscillator

will lock to the positive zero crossings of the ac

reference input. The ac signal must be symmetric

(e.g. sine wave, square wave, etc.) and have a

peak to peak amplitude greater than 100 mV. A

signal with 1 Vrms amplitude is recommended.

The phase accuracy of the reference channel is

specified for a 1Vrms sinewave in the symmetric

trigger mode.

Expand Channel 2

The output EXPAND is toggled by pressing the

key in the Channel 2 EXPAND section. The

expand status is indicated by the X10, expand on,

and the X1, expand off, LED's. Only the Channel

2 OUTPUT is affected, the Y (RSINØ) output is

not expanded. Ø and X6 may not be expanded.

If the upper TRIGGER MODE LED is on, the

mode is POSITIVE. The trigger threshold is +1V

and the reference oscillator will lock to the positive

going transitions of the reference input. This

mode triggers on the rising edges of a TTL type

pulse train. The pulse width must be greater than

1 µS.

If the lower TRIGGER MODE LED is on, the mode

is NEGATIVE. The trigger threshold is -1V and

the reference oscillator will lock to the negative

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going transitions of the reference input. This

mode triggers on a negative pulse train or on the

falling edges of a TTL type pulse train

(remembering that the input is ac coupled). The

pulse width must be greater than 1 µS.

Time Constant

There are two post demodulator low pass filters,

labeled PRE and POST. The PRE filter precedes

the POST filter in the output amplifier. Each filter

provides 6 dB/oct attenuation.

Reference Mode

The PRE filter time constant ranges from 1 mS to

100 S and is selected by the two keys below the

PRE filter indicator LED's. Holding down either

key will advance the time constant four times a

second in the desired direction.

The REFERENCE MODE indicator toggles

between f and 2f whenever the MODE key is

pressed. When the MODE is f, the lock-in will

detect signals at the reference input frequency.

When the MODE is 2f, the lock-in detects signals

at twice the reference input frequency. In either

case, the reference oscillator has a maximum

frequency of 100 KHz, thus, when in the 2f mode,

the reference input frequency may not exceed 50

KHz.

In many servo applications, no time constant is

needed. The SR530 may be modified to reduce

the output time constant to about 20 µS. Contact

the factory for details.

The POST filter time constant can be set to 1 S or

0.1 S, or can be removed altogether, NONE, using

the two keys below the ENBW indicators. When

set to NONE, the total attenuation is that of the

PRE filter, or 6 dB/oct. When the POST filter is 1

S or 0.1S, the total attenuation is 12 dB/oct for

frequency components beyond the larger of the

POST and PRE filter bandwidths (reciprocal time

constant).

Reference Display

The REFERENCE DIGITAL DISPLAY shows

either the reference oscillator frequency or phase

shift. The displayed parameter toggles between

the two whenever the SELECT key is pressed.

The appropriate scale indicator below the display

will be on. It is useful to check the frequency

display to verify that the lock-in has correctly

locked to your reference. The reference frequency

is measured to 1 part in 256 resolution at all

frequencies. The display reads .000 if there is no

reference input and 199.9 kHz if the input

frequency exceeds 105 kHz.

Noise Measurements

When the DISPLAY is set to X NOISE Y NOISE,

none of the PRE and POST indicator LED's are

on. Instead, one of the two ENBW indicators will

be on, showing the Equivalent Noise Bandwidth of

the rms noise calculation. The ENBW is set using

the keys below the ENBW indicator LED's (same

keys as used to set the POST filter). The PRE

filter keys do nothing in this case. Pressing the

upper key when the bandwidth is already 1 Hz will

reset the rms noise average (output) to zero,

restarting the calculation. Likewise with pressing

the lower key when 10 Hz is already selected.

Phase Controls

The phase shift between the reference oscillator of

the lock-in and the reference input signal is set

using the four keys in the PHASE section. The

two keys below the FINE label increment the

phase setting in small amounts. A single key

press will change the phase by 0.025 degrees in

the desired direction. Holding the key down will

continue to change the phase with larger and

larger steps with the largest step being 10

degrees. The two 90° keys are used to change

the phase by 90 degree increments. The upper

key will add 90 degrees and the lower key will

subtract 90 degrees. Holding both keys down at

once sets the phase shift back to zero. The

REFERENCE DIGITAL DISPLAY automatically

displays the phase whenever any of the PHASE

keys are pressed. The phase ranges from -180

degrees to +180 degrees and is the phase delay

from the reference input signal.

The noise is the rms deviation of the output within

a 1 or 10 Hz equivalent noise bandwidth about the

reference frequency. A dc output does not

contribute to the noise, the noise is determined

only by the ac 'wiggles' at the output. By

measuring the noise at different frequencies, the

frequency dependence of the noise density can be

found. This usually has the form of v

~ 1/f.

noise

The noise computation assumes that the noise

has a Gaussian distribution (such as Johnson

noise). Since the computation takes many time

constants (reciprocal ENBW), the noise output

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should be allowed to approach a steady value

before a reading is taken. For the 1 Hz ENBW,

this time is on the order of 15 to 30 seconds; for

the 10 Hz ENBW, the output stabilizes much

faster. The noise output will vary slightly since

there will always be noise variations that are slow

compared to the bandwidth. Any DC component

in the output will not contribute to the noise.

However, a large DC output will cause the noise

computation to initially rise to a large value before

approaching the final answer. As a result, the

computation will take longer to settle.

the instrument. All displays return to normal after

3 seconds.

Local and Remote

When the instrument is programmed via the

computer interface to be in the REMOTE state

WITHOUT LOCK-OUT, the LOCAL key will return

the instrument to LOCAL front panel control. If

the instrument is in the REMOTE WITH LOCK-

OUT state, no front panel key will return the status

to LOCAL. In this case, a RETURN TO LOCAL

command must be sent over the computer

interface or the power must be turned off and back

on.

If the OVLD indicator is blinking four times a

second, then either the X or Y output is

overloaded and the corresponding noise

calculation should be ignored. If the OVLD LED is

on continuously, then the input signal is

overloading the ac amplifier or time constant

filters. In this case, both noise outputs will be

wrong.

Defaults

If the LOCAL key is held down when the POWER

is turned on, the instrument settings will be set to

the defaults shown below instead of the settings in

effect when the power was turned off.

To obtain a value for the noise density, the noise

reading should be divided by the square root of

the ENBW. Thus, when the ENBW is 1 Hz, the

noise output is the noise density, and when the

ENBW is 10 Hz, the noise density is the noise

output divided by √10. For example, if the input

noise is measured to be 7 nV with the ENBW set

to 1 Hz, the noise density is 7 nV/√Hz. Switching

the ENBW to 10 Hz results in a faster

measurement and a reading of 22 nV on the

output. The noise density is 22 nV/√10 Hz or 7

nV/√Hz. At frequencies » 10 Hz, the noise density

should be independent of the ENBW.

Parameter

Setting

BANDPASS

LINE

OUT

LINE X 2

OUT

SENSITIVITY

DYN RES

DISPLAYS

EXPANDS

OFFSETS

500 mV

LOW

X Y

OFF

OFF (value=0)

PRE TIME CONSTANT 100 mS

POST TIME CONSTANT 0.1 S

ENBW

REFERENCE MODE

TRIGGER MODE

1 Hz

SYMMETRIC

Power

This is the instrument's POWER switch. When the

power is turned off, the front panel settings are

retained so that the instrument will return to the

same settings when the power is next turned on.

The SR530 always powers up in the LOCAL

mode.

REFERENCE DISPLAY FREQUENCY

PHASE SHIFT 0°

Whenever default values are used at power up,

the red ERR LED will turn on for about 3 seconds.

If the ERR LED is on when the instrument is

powered on without the LOCAL key down, then

the instrument is ignoring the retained settings.

This can be due to a low battery.

The D/A outputs X5 and X6 are not retained

during power off. X5 always becomes the RATIO

output at power on and X6 is always reset to zero.

When the power is turned on, the CHANNEL 1

OUTPUT DIGITAL DISPLAY will show the

SERIAL NUMBER of the instrument and the

CHANNEL 2 OUTPUT DIGITAL DISPLAY will

show the firmware VERSION. The REFERENCE

DIGITIAL DISPLAY shows the model number of

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Voltage Current Available

SR530 Guide to Operation

Rear Panel

+20

100 mA

10 mA

-20

100 mA

AC Power

Signal ground

Digital ground

The ac line voltage selector card, line fuse, and

line cord receptacle are located in the fuse holder

at the left side of the rear panel. See the section,

Preparation for Use at the front of this manual for

instructions on setting the ac voltage selector and

choosing the correct fuse.

General Purpose A/D and D/A

There are four analog input ports, labeled X1

through X4. These inputs may be digitized and

read via the computer interfaces. The range is -

10.24 V to +10.24 V and the resolution is 2.5 mV.

The input impedance is 1 MΩ. A digitization can

be performed in about 3 mS but the result may

take longer to transmit over the interface being

used.

GPIB Connector

The SR530 has an IEEE 488 (GPIB) interface built

in. The GPIB address is set using SW1 located to

the right of the interface connectors. Refer to

page 7 for switch setting details.

There are two analog output ports, labeled X5 and

X6. The voltages at these ports may be

programmed via the computer interfaces. The

range is -10.24 V to +10.24 V and the resolution is

2.5 mV. The output impedance is <1Ω and the

output current is limited to 20 mA.

RS232 Connector

The SR530 has an RS232 interface. The

connector is configured as a DCE. The baud rate,

parity, stop bits, and echo mode are selected

using SW2 located to the right of the interface

connectors. Refer to Page 7 for switch setting

details.

Ratio

Output X5 is the ratio output when not

programmed by the computer interface or set via

the front panel. X5 becomes the ratio output

whenever the unit is turned on.

Signal Monitor Output

This BNC provides the buffered output of the

signal amplifiers and filters. This is the signal just

before the demodulator. The output impedance is

<1Ω. When a full scale input is applied, the peak-

to-peak amplitude at this output is 20 mV, 200 mV

or 2 V for dynamic reserve settings of high, norm,

and low, respectively.

The voltage at X5 is the ratio of the Channel 1

Output to the analog voltage at port X1. An output

of 10 V corresponds to a ratio of 1. The ratio is

computed by digitizing the Channel 1 Output and

the voltage at port X1 and then taking the ratio.

The resolution is 2.5 mV. For best accuracy, the

sensitivity should be set to provide at least a 50%

full scale signal and the analog denominator (X1)

should be 5V or greater. The ratio is updated

approximately every 3 mS. For the Ratio feature

to work, the voltage at the denominator input must

exceed 40 mV.

Preamp Connector

This 9 pin "D" connector provides power and

control signals to external peripherals such as pre-

amplifiers. The available power is described

below.

When the DISPLAY is set to D/A, the ratio output

is 10 times the magnitude, R, divided by X1.

Internal Oscillator

The INTERNAL OSCILLATOR is a voltage

controlled oscillator with a sine wave output . To

use the oscillator as the reference source, connect

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the REF OUTPUT on the rear panel to the REF

INPUT on the front panel. The REF OUTPUT is a

1 Vrms sine wave. The SINE OUTPUT may be

used as the stimulus to the experiment. The SINE

OUTPUT can be set to three amplitudes, 1 V, 100

mV, and 10 mV (rms) using the amplitude switch.

The output impedance is 600Ω. The AMP CAL

screw adjusts the amplitude.

2) If the VCO INPUT is left open, then the

oscillator will run at the top of its range (i.e. 10 Hz,

1 KHz, or 100 KHz).

3) A 10 KΩ potentiometer may be connected from

the VCO INPUT to ground. This pot will then set

the frequency.

4) Connect the VCO INPUT to an external voltage

source which can provide 0 to 10V.

The oscillator frequency is controlled by the VCO

INPUT voltage. A voltage from 0V to 10V will

adjust the frequency according to the VCO

RANGE selected. Three ranges are available, 1

Hz/V, 100 Hz/V, and 10 KHz/V. The input

impedance is 10 kΩ. The FREQUENCY CAL

screw adjusts the frequency.

In all four cases, if the REF OUTPUT is connected

to the REFERENCE INPUT on the front panel, the

frequency may be read on the front panel

REFERENCE DIGITAL DISPLAY or via the

computer interfaces.

There are four ways to set the frequency:

1) Connect X5 or X6 (D/A outputs) to the VCO

INPUT. The frequency can now be set from the

front panel by setting the DISPLAY to D/A and

adjusting X5 or X6. The frequency is also

controllable via the computer interfaces by

programming X5 or X6.

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SR530 Guide to

Programming

An example of a multiple command is:

G 5; T 1,4; P 45.10 <cr>

It is not necessary to wait between commands.

The SR530 has a command input buffer of 256

characters and processes the commands in the

order received. Likewise, the SR530 has an

output buffer (for each interface) of 256

characters.

The SR530 Lock-in Amplifier is remotely

programmable via both RS232 and GPIB

interfaces. It may be used with laboratory

computers or simply with a terminal. All front

panel features (except signal input selection and

power) may be controlled and read via the

computer interfaces. The SR530 can also read

the analog outputs of other laboratory instruments

using its four general purpose analog input ports.

There are also two programmable analog output

ports available to provide general purpose control

voltages.

In general, if a command is sent without

parameters, it is interpreted as a request to read

the status of the associated function or setting.

Values returned by the SR530 are sent as a string

of ASCII characters terminated usually by carriage

return, line-feed. For example, after the above

command is sent, the following read commands

would generate the responses shown below.

Communicating with the SR530

Before using either the RS232 or GPIB interface,

the appropriate configuration switches need to be

set. There are two banks of 8 switches, SW1 and

SW2, located on the rear panel. SW1 sets the

GPIB address and SW2 sets the RS232

Command Response from the SR530

G <cr>

T 1 <cr>

P <cr>

5<cr><lf>

4<cr><lf>

45.10<cr><lf>

parameters. The configuration switches are read

continuously and any changes will be effective

immediately. For details on switch settings, see

page 7 at the front of this manual.

The choice of terminating characters sent by the

SR530 is determined by which interface is being

used and whether the 'echo' feature is in use. The

terminating sequence for the GPIB interface is

always <cr><lf> (with EOI). The default sequence

for RS232 is <cr> when the echo mode is off, and

<cr><lf> when the echo mode is on. The

Command Syntax

Communications with the SR530 use ASCII

characters. Commands to the SR530 may be in

either UPPER or lower case.

terminating sequence for the RS232 interface may

be changed using the J command.

Note that the terminating characters are sent with

each value returned by the SR530. Thus, the

response to the command string G;T1;P<cr> while

using the RS232 non-echo mode would be

5<cr>4<cr>45.10<cr>.

A command to the SR530 consists of one or two

command letters, arguments or parameters if

necessary, and an ASCII carriage return (<cr>) or

line-feed (<lf>) or both. The different parts of the

command do not need to be separated by spaces.

If spaces are included, they will be ignored. If

more than one parameter is required by a

Front Panel Status LED's

command, the parameters must be separated by

a comma. Examples of commands are:

The ACT LED flashes whenever the SR530 is

sending or receiving characters over the computer

interfaces.

G 5 <cr>

T 1,4 <cr> set the pre filter to 30 mS

F <cr> read the reference frequency

P 45.10 <cr> set phase shift to 45.10¡

set the sensitivity to 200 nV

The ERR LED flashes whenever an error has

occurred, such as, an illegal command has been

received, a parameter is out of range, or a

communication buffer has exceeded 240

X 5,-1.23E-1 <cr> set port X5 to -0.123 V

Multiple commands may be sent on a single line.

The commands must be separated by a semicolon

(;) character. The commands will not be executed

until the terminating carriage return is sent.

characters. This LED flashes for about three

seconds on power-up if the battery voltage is

insufficient to retain previous instrument settings.

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The REM LED is on whenever the SR530 is

programmed to be in the remote state.

DIGITAL DISPLAY. Typing the phase read

command, P<cr>, will now return the string 45.00

to the terminal.

RS232 Echo and No Echo

Operation

Now read the gain using the sensitivity read

command, G<cr>. The response should be 24

meaning that the sensitivity is at the 24th setting or

500 mV. Change the sensitivity by typing

G19<cr>. The sensitivity should now be 10 mV.

Check the front panel to make sure this is so.

In order to allow the SR530 to be operated from a

terminal, an echo feature has been included which

causes the unit to echo back commands received

over the RS232 port. This feature is enabled by

setting switch 6 on SW2 to the DOWN position. In

this mode, the SR530 will send line-feeds in

addition to carriage returns with each value

returned and will also send the prompts 'OK>' and

'?>' to indicate that the previous command line

was either processed or contained an error.

Operating the SR530 from a terminal is an ideal

way to learn the commands and responses before

attempting to program a computer to control the

SR530. When the unit is controlled by a

The Channel 1 Output of the lock-in is read by

typing the command, Q1<cr>. The response is a

signed floating point number with up to 5

significant digits plus a signed exponent. Change

the gain to 10 uV using the G10 command. The

response to the Q1 command will now be similar

to the previous one except that the exponent is

different.

Attach a DC voltmeter to the X6 output on the rear

panel. The range should allow for 10V readings.

The voltage at the X6 output can be set using the

X6 command. Type X6,5.0<cr> and the X6 output

will change to 5.0V. To read this back to the

terminal, just type X6<cr>. When setting the X6

voltage, the voltage may be sent as an integer (5),

real (5.000), or floating point (0.500E1) number.

Now connect the X6 output to the X1 input (also

on the rear panel). X1 through X4 are analog

input ports. To read the voltage on X1, simply

type X1<cr>. The response 5.000 should appear

on the terminal. The analog ports X1 through X6

can be used by your computer to read outputs of

other instruments as well as to control other

laboratory parameters.

computer, the echo feature should be turned off to

prevent the sending of spurious characters which

the computer is not expecting.

Try-Out with an ASCII Terminal

Before attempting any detailed programming with

the SR530, it is best to try out the commands

using a terminal. Connect a terminal with an

RS232 port to the RS232 connector on the rear

panel of the SR530. A 'straight' RS232 cable is

required since the SR530 is a DCE and the

terminal is a DTE. Set the baud rate, parity, and

stop bits to match the terminal by setting SW2 per

the switch setting table given on page 7. The

echo mode should be enabled (switch 6 DOWN).

After setting SW2 and connecting the terminal,

hold down the LOCAL key while turning the unit

on. This causes the SR530 to assume its default

settings so that the following discussion will agree

with the actual responses of the SR530. The ACT

and ERR LED's on the front panel will flash for a

second and the sign-on message will appear on

the terminal. Following the message, the prompt

'OK>' will be displayed. This indicates that the

SR530 is ready to accept commands.

At this point, the user should experiment with a

few of the commands. A detailed command list

follows.

Type the letter 'P' followed by a carriage return

(P<cr>). The SR530 responds by sending to the

terminal the characters 0.00 indicating that the

phase is set to 0 degrees. In general, a command

with no arguments or parameters reads a setting

of the unit. To set the phase to 45 degrees, type

the command, P45<cr>. To see that the phase

did change, use the SELECT key on the front

panel to display the phase on the REFERENCE

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Dyn Res

LOW

NORM

HIGH

SR530 Command List

The leading letters in each command sequence

specify the command. The rest of the sequence

consists of parameters. Multiple parameters are

separated by a comma. Those parameters shown

in {} are optional while those without {} are

required. The variables m and n represent

integers while v represents a real number.

Parameters m and n must be expressed in integer

format while v may be in integer, real, or floating

point format.

Note that not all dynamic reserve settings are

allowed at every sensitivity.

E m {,n}

The E command sets and reads the status of the

output expands. If m is "1", then Channel 1 is

selected, if m is "2", Channel 2 is selected. The

parameter m is required. If n is "1", the E

command expands the selected output channel. If

n is "0", the expand is turned off for the selected

channel. If n is absent, the expand status of the

selected channel is returned. Note that the

expands do not affect the X and Y BNC outputs,

only the Channel 1 and 2 outputs.

The A command causes the auto offset (rel)

function to execute. Auto offset is performed by

reading the output and using that value as the

appropriate offset. Every time an "AX" command

is received, the auto offset function is executed on

the X output. The "AY" command auto offsets the

Y output. The "AR" command auto offsets the R

output. Note that "AX" and "AY" will affect the R

output but "AR" will not affect X and Y. The "AP"

command will execute the auto-phase routine.

This is done by setting the reference phase shift

with the present phase difference between the

signal and the reference input. The ¯ output then

reads zero and the reference display reads the

signal phase shift. "AP" maximizes X and

minimizes Y but R is unaffected. The A

commands may be issued at any time, regardless

of the DISPLAY setting.

The F command reads the reference frequency.

For example, if the reference frequency is 100 Hz,

the F command returns the string "100.0". If the

reference frequency is 100.0 kHz, the string

"100.0E+3" is returned. The F command is a read

only command.

G {n}

If n is included, the G command sets the gain

(sensitivity). If n is absent, the gain setting is

returned.

Sensitivity

10 nV

20 nV

50 nV

100nV

200nV

500nV

B {n}

If n is "1", the B command sets the bandpass filter

in. If n is "0", the bandpass filter is taken out. If n

is absent, then the bandpass filter status is

returned.

µV

C {n}

10 10 µV

11 20 µV

12 50 µV

13 100µV

14 200µV

15 500µV

16 1 mV

17 2 mV

18 5 mV

19 10 mV

20 20 mV

21 50 mV

22 100mV

If n is "1", the C command sets the reference LCD

display to show the phase setting. If n is "0", the

LCD will display the reference frequency. If n is

absent, the parameter being displayed (frequency

or phase) is returned. Note that the P and F

commands are used to read the actual values of

the phase and frequency.

D {n}

If n is included, the D command sets the dynamic

reserve. If n is absent, the dynamic reserve

setting is returned.

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23 200mV

24 500mV

90° Up

90° Down

Zero Phase (Simultaneous 90° Up and

Down)

Reference Trigger Mode

Note that sensitivity settings below 100 nV are

allowed only when a pre-amplifier is connected.

10 Reference Mode (f/2f)

11 Degrees Up

12 Degrees Down

The H command reads the pre-amplifier status.

If a pre-amplifier is connected, a "1" is returned,

otherwise, a "0" is returned. The H command is a

read only command.

13 Channel 2 Rel

14 Channel 2 Offset (On/Off)

15 Channel 2 Offset Up

16 Channel 2 Offset Down

17 Channel 2 Expand

18 Output Display Up

19 Output Display Down

20 Channel 1 Expand

21 Channel 1 Rel

I {n}

If n is included, the I command sets the remote-

local status. If n is absent, the remote-local status

is returned.

Status

22 Channel 1 Offset (On/Off)

23 Channel 1 Offset Up

24 Channel 1 Offset Down

25 Dyn Res Up

26 Dyn Res Down

27 Sensitivity Up

Local: all front panel keys are operative

Remote: front panel keys are not

operative. The LOCAL key returns the

status to local.

28 Sensitivity Down

29 Local

Lock-out: front panel keys are not

operative. No key returns the status to

local. Another I command is needed to

return to local.

30 Line X 2 Notch Filter

31 Line Notch Filter

32 Bandpass Filter

L m {,n}

When using the GPIB interface, the REN, LLO,

and GTL commands are not implemented. The I

command is used by both interfaces to set the

remote-local status.

The L command sets and reads the status of the

line notch filters. If m is "1", then the 1X line

notch is selected, if m is "2", the 2X line notch is

selected. The parameter m is required. If n is "1",

the L command sets the selected filter in. If n is

"0", the selected filter is taken out. If n is absent,

the status of the selected filter is returned.

J {n1,n2,n3,n4}

The J command sets the RS232 end-of-record

characters sent by the SR530 to those specified

by the decimal ASCII codes n1-n4. If no argument

is included, the end-of-record sequence returns to

the default (a carriage return), otherwise, up to

four characters may be specified. The end-of-

record required by the SR530 when receiving

commands is not affected.

M {n}

If n is "1", the M command sets the reference

mode to 2f. If n is "0", the reference mode is set

to f. If n is absent, the reference mode is returned.

N {m}

If m is "1", the N command sets the ENBW to 10

Hz. If m is "0", the ENBW is set to 1 Hz. If m is

absent, the ENBW setting is returned.

K n

The K command simulates a front panel key

press. The effect is exactly the same as pressing

the selected key once. The parameter n is

required.

OX {n} {,v}

OY {n} {,v}

OR {n} {,v}

Key

The "OX", "OY", and "OR" commands set the

offsets for the X, Y, and R outputs respectively. If

n is "1", the offset is turned on. If n is "0", the

offset is turned off. If n and v are absent, the

offset status (on or off) is returned. (The value of

the offset is read using the S and Q commands.)

Post Time Constant Up

Post Time Constant Down

Pre Time Constant Up

Pre Time Constant Down

Select Display (f/phase)

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If n is included, then v may be sent also. v is the

offset value up to plus or minus full scale in units

of volts. For example, to offset half of full scale on

the 100 µV sensitivity, v should be "50.0E-6" or an

equivalent value. However, if the sensitivity is

then changed to 200 µV, the offset is now half of

the new full scale or 100 µV. When the sensitivity

is changed, the offset is preserved as a constant

fraction of full scale rather than as a voltage

referred to the input. The expand function will, on

the other hand, preserve the value of the offset as

an input referred voltage. Once a value of v is

sent, the offsets may be turned off and on without

losing the offset values by using the O commands

without the v parameter. Note that the X and Y

offsets will affect the R output but the R offset

does not affect the X or Y output.

R Offset

X Noise

X5 (D/A)

Y Noise

X6 (D/A)

T m {,n}

The T command sets and reads the status of the

time constants. If m is "1", the pre time constant

is selected, if m is "2", the post time constant is

selected. The parameter m is required. If n is

included, the T command sets the selected time

constant. If n is absent, the setting of the selected

time constant is returned.

Pre Time Constant (m=1)

100

300

P {v}

If v is absent, the P command returns the

reference phase shift setting from -180 to +180

degrees. When v is included, the phase is set to

the value of v up to ±999 degrees.

10 30

11 100

Post Time Constant (m=2)

none

The Q commands return the output values in

units of volts or degrees. For an input signal of 50

µV on a full scale sensitivity of 100 µV, a Q

command will return the string "50.00E-6". "Q1"

and "Q2" read the parameters being shown on the

Channel 1 and Channel 2 output displays as

selected with the S command. "QX" and "QY"

read the X (RCOS Ø) and Y (RSIN Ø) BNC

outputs.

0.1

U m {,n}

The U command sets and reads the unit's

calibration bytes. m is the address offset of the

byte, 0-511. If n is absent, the value of the

addressed calibration byte is returned. If n is

included, the addressed calibration byte is set to

the value of n, 0-255. The new value will be in

effect until the power is turned off or a reset

command is issued. Use of this command is not

recommended.

R {n}

If n is included, the R command sets the

reference input trigger mode. If n is absent, the

trigger mode is returned.

V {n}

Mode

ositive

Symmetric

Negative

If n is included, the V command sets the GPIB

SRQ (service request) mask to the value n (0-

255). If n is absent, the value of the SRQ mask is

returned.

S {n}

W {n}

If n is included, the S command selects the

The W command sets and reads the RS232

character wait interval. If n is included, the SR530

will wait nx4 mS between characters sent over the

RS232 interface. This allows slow computer

interfaces to keep up. n can range from 0 to 255.

If n is absent, the wait value is returned. The wait

interval is set to 6 on power-up.

parameters shown on the Channel 1 and 2 analog

meters, output digital displays, and output BNC's.

If n is absent, the displayed parameter is returned.

Channel 1 Channel 2

X Offset

Y Offset

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X n {,v}

Bit 0

n designates one of the 6 general purpose analog

ports located on the rear panel. If n is 1,2,3, or 4,

the X command will return the voltage on the

designated analog input port (X1-X4) in volts. If n

is 5 or 6, then v may also be sent. If v is included,

the designated analog output port (X5 or X6) will

be set to v volts where v has the range -10.238V

to +10.238V. If v is absent, the output value of the

selected port is returned. On power-up, port X5 is

the ratio output. An "X 5" command will read the

ratio output. An "X 5" command with the

parameter v will set port X5 to v volts, overriding

the ratio output. Port X5 will return to the ratio

output on power-up or reset.

Not Used

Bit 1

Command Parameter Out of Range. This bit is

set if a parameter associated with a command is

not in the allowed range.

Bit 2

No Reference. This bit is set when no reference

input is detected, either because the amplitude is

too low or the frequency is out of range.

Bit 3

Unlock. This bit is set when the reference

oscillator is not locked to the reference input. If

there is no reference input, bit 2 (no reference) will

be set but bit 3 (unlock) may not be.

Y {n}

The Y command reads the status byte. (See the

following section for a definition of the Status

Byte.) n designates one bit, 0-7, of the status

byte. If n is included, the designated bit of the

status byte is returned. The bit which is read is

then reset. If n is absent, the value of the entire

byte is returned and all status bits are then reset.

This status byte may also be read over the GPIB

using the serial poll command.

Bit 4

Overload. This bit is set if there is a signal

overload. This can happen when the sensitivity is

too high, the dynamic reserve is too low, the offset

is on, or the expand is on. Overloads on the

general purpose A/D inputs or the ratio output are

not detected.

The Z command causes an internal reset. All

settings return to the default values shown on

page 15. The ERR LED will be on for about three

seconds to indicate that the stored instrument

settings are being ignored. If the RS232 echo

mode is on, the sign-on message is sent over the

RS232 interface.

Bit 5

Auto Offset Out of Range. This bit is set if the

auto offset function cannot zero the output

because the output exceeded 1.024X full scale.

Bit 6

SRQ. This bit is set if the SR530 has generated

an SRQ on the GPIB interface. This bit is reset

after the SR530 has been serial polled. This bit is

set only for status reads via a serial poll, ie., Bit 6

always zero for the RS232 .

Status Byte

The SR530 maintains an 8-bit status register

which the user may read to obtain information on

the unit's status. The status byte may be read in

two ways: by sending the Y command, which

returns the value of the byte in ASCII coded

decimal, or, when using the GPIB, by performing a

serial poll. The returned status byte reflects all of

the status conditions which have occurred since

the last time the byte was read. After the status

byte has been read, it is cleared. Thus, the status

byte should be read initially to clear all previous

conditions (especially after a power up or after

settings have been changed).

Bit 7

Command Error. This bit is set when an illegal

command string is received.

Errors

Whenever a 'parameter out of range' or an

'unrecognized command' error occurs, the

appropriate status bits are set and the ERR LED

flashes. In addition, any commands remaining on

the current command line (up to the next <cr>) are

lost. The ERR LED will also light if any of the

internal communication buffers overflows. This

occurs when 240 characters are pending on the

command queue or output queue. The ERR LED

will go off as soon as all buffers drop below 200

The definitions for each bit of the status byte are

given below:

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characters again.

mode should be off when not debugging

the GPIB interface.)

Reset

Your computer requires an RS232 control

line to be asserted, but your cable does

not pass it between the SR530 and the

computer, or, your computer is not

asserting the DTR line on the RS232.

The Z command resets the unit to its default state.

The default front panel settings are listed in the

DEFAULTS section of the Guide to Operations.

In addition, the interface status returns to LOCAL,

the SRQ mask is cleared, the RS232 character

WAIT interval is set to 6, and the terminating

sequence is reset to the proper defaults.

Common Software Problems include:

You have sent the wrong command to ask

for data from the SR530. Your program

will wait forever for a response which is

not going to come. This may not be your

fault; we have seen Microsoft's Interpreted

Basic on the IBM PC occasionally send a

curly bracket (ASCII 253) when it was

supposed to have sent a carriage return

(ASCII 13).

The command and output buffers are cleared by

the Z command. Therefore, it is bad practice to

use the Z command before all previous commands

have been processed and all responses have

been received.

Trouble-Shooting Interface

Problems

Your computer's baud rate has been

changed and no longer matches the

SR530's baud rate.

If you are having difficulty getting your computer to

communicate with the SR530 look to the sections

on the RS232 and GPIB interfaces for some tips

specific to your particular interface.

The initial command sent to the SR530

was invalid due to a garbage character left

in the command queue from power-up, or,

the first character in you computer's UART

is garbage, also due to power-up. It is

good practice to send a few carriage

returns to the SR530 when your program

begins, and have your program clear-out

its UART at the start of your program.

An ASCII terminal is a valuable aid for debugging

interface problems. You can use it to:

become familiar with the SR530's

command structure,

see GPIB bus transactions by using the

GPIB echo mode,

The SR530 is not sending the correct

'end-of- record' marker for your computer.

For example, it appears that Microsoft's

Rev 3.2 FORTRAN on the IBM PC under

DOS 2.1 requires two carriage returns for

an end-of-record marker. The J command

can be used to set the SR530 end-of-

record marker to 2 carriage returns. [The

end-of-record marker is that sequence

which indicates that the response is

complete. From the keyboard, a single

carriage return is the end-of-record

marker.]

eavesdrop on transactions when using the

RS232 interface,

substitute a human for the SR530 by using

a null modem cable ( to make the DTE a

DCE) and attaching the terminal to the

port to which you would normally have

connected the SR530. This allows you to

test your program's responses to inputs

which you provide from the terminal.

Common Hardware Problems include:

Answers are coming back from the SR530

too fast, overwriting the end-of-record

markers, and causing the computer to

hang waiting for a complete response. In

this case, the W command can be used to

slow down the response time of the

SR530 preventing overwriting.

The RS232 or GPIB cables are not

properly attached.

The configuration switches for the RS232

characteristics or GPIB address are not

set correctly (Make sure the RS232 echo

is off when using the RS232 interface with

a computer. The GPIB with RS232 echo

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Answers are coming back from the SR530

too slowly due to the W6 default setting for

the character interval time. Use the W

command to speed up the transmission

from the SR530. This can cause

command is:

J {n1,n2,n3,n4}

where n1, n2, n3, and n4 are decimal values

between 0 and 255 corresponding to the ASCII

codes of the desired termination characters. For

instance, if the desired termination sequence is an

asterisk, (ASCII 42), two carriage returns, (ASCII

13), and a line-feed, (ASCII 10), the appropriate

command is:

problems for the GPIB interface if the echo

mode is on (switch 6 of SW1).

The SR530 with the RS232

Interface

The RS232 is a popular serial interface standard

for bit serial communication. Despite the

existence of the standard there are many

permutations of control lines, baud rates, and data

formats. If you do not have a lot of experience

interfacing RS232 equipment you should read

Appendix B for a description of the RS232 and

interfacing tips.

J 42,13,13,10

If a G command is sent requiring an answer of 24

(sensitivity = 500 mV), the SR530 would respond

with the string

24*<cr><cr><lf>

Up to four terminating characters may be specified

by the J command. If no arguments are sent with

the J command, the terminating sequence returns

to the default (echo on: <cr><lf>; echo off: <cr>).

Data Communications Equipment

(DCE)

The SR530 is configured as DCE so that it may be

connected directly to a terminal. If the SR530 is to

be interfaced with another DCE device, a special

cable (sometimes referred to as a 'modem' cable)

is required. To use the RS232 interface you must

set the switches in SW2 to match your computer's

baud rate, parity, and number of stop bits. Refer

to Page 7 for details.

The J command does not affect the terminating

character (<cr>) required at the end of commands

received by the SR530. It also does not affect the

terminating sequence sent with data over the

GPIB interface.

The SR530 with the GPIB

Interface

Wait Command

For a brief introduction to the GPIB standard,

please read Appendix C at the back of this

manual. Before using the GPIB interface you

must set the switches in SW1 per the instructions

on page 7.

The SR530 normally waits until the RS232 'Clear

to Send' control line (CTS) is asserted before

sending characters. However, some computers

do not set and reset the CTS line, possibly

causing the SR530 to send data when the

computer is not ready to read it. The SR530 may

be 'slowed down' using the W command. Sending

'Wn' causes the unit to wait nx4 mS before

sending each character over the RS232 bus. The

command W0 sets the wait interval to zero and

results in the fastest transmission. The wait

interval is set to 6 (24 mS)on power-up.

GPIB Capabilities

The GPIB capabilities of the SR530 consistent

with IEEE standard 488 (1978) are shown in the

table below. Also shown are the responses of the

SR530 to some standard commands.

Code Function

Termination Sequences

SH1

AH1

Source handshake capability

Acceptor handshake capability

Basic Talker, Serial Poll, Unaddressed to

talk if addressed to listen

The default RS232 termination characters are

sufficient to interface with most computers,

however, it will occasionally be necessary to send

special terminating sequences to fit the

requirements of some computers. This can be

done with the J command. The format for the

Basic Listener, Unaddressed to listen if

addressed to talk

SR1

PP0

Service request capability

No parallel poll capability

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DC1

RL0

Device Clear capability

REN,LLO, GTL not implemented.

'I' command sets Remote-Local.

Any SRQ generated by the 'no reference, 'unlock',

'overload', and 'auto over-range' conditions will

also reset the corresponding bit in the SRQ mask

byte. This is to prevent a constant error condition

(such as no reference applied to the input) from

continually interrupting the controller. When such

an SRQ occurs, the controller should change

some parameter so as to solve the problem, and

then re-enable the SRQ mask bit again using the

V command.

SR530 Response to GPIB Commands

Mnemonic Command

DCL

SDC

Response

Device Clear Same as Z command

Selected

Same as Z command

Device Clear

Serial Poll

Enable

SPE

Send Status Byte,

& clear status byte

GPIB with RS232 Echo Mode

Because the SR530 can be controlled by an

RS232 interface as well as the GPIB, the remote-

local functions are not standard. There is no local

with lock out state. When in the local state,

remote commands are processed, even without

the REN command being issued. This is because

the RS232 interface has no provision for bus

commands and remote commands over the

RS232 interface would never be enabled.

It is sometimes useful when debugging a GPIB

system to have some way of monitoring exactly

what is going back and forth over the bus. The

SR530 has the capability to echo all characters

sent and received over the GPIB to its RS232 port.

This mode of operation is enabled by setting

switch 6 of SW1 to the DOWN position. The baud

rate, stop bits, and parity of the RS232 port are

still set by SW2. Of course, the RS232 port

operates at much lower speeds than the GPIB and

will slow down the GPIB data rate in this mode.

(Use the W0 command to allow the RS232

interface to run at full speed, otherwise, the GPIB

transactions may take so long that the controller

can hang.) During actual use, this mode should

be disabled.

Serial Polls and Service Requests

The status byte sent by the SR530 when it is serial

polled is the same status byte which is read using

the Y command (except for bit 6, SRQ). Ofcourse,

when the SR530 is serial polled, it does not

encode the status byte as a decimal number. The

SR530 can be programmed to generate a service

request (SRQ) to the GPIB controller every time a

given status condition occurs. This is done using

the V{n} command. The mask byte, n (0-255), is

the SRQ mask byte. The mask byte is always

logically ANDED with the status byte. If the result

is non-zero, the SR530 generates an SRQ and

leaves the status byte unchanged until the

The SR530 with BOTH Interfaces

If both interfaces are connected, commands may

be received from either interface. Responses are

always sent to the source of the request (except in

GPIB echo mode). It is unwise to send commands

from the two interfaces at the same time since the

characters from different sources can become

interleaved on the command queue and result in

'unrecognized command' errors.

controller performs a serial poll to determine the

cause of the service request. When the unit has

been serial polled, the status byte is reset to

reflect all of the status conditions which have

occurred since the SRQ was generated.

For example, if we want to generate an SRQ

whenever there is an overload or unlock condition,

we need an SRQ mask byte equal to 00011000

binary, or 24 decimal ("V24" command). The byte

00011000 binary corresponds to the status byte

with the 'no reference' and 'unlock' status bits set.

If an overload occurs, then an SRQ will be

generated. The serial poll will return a status byte

showing SRQ and overload. If an unlock condition

occurs before the serial poll is concluded, another

SRQ will be generated as soon as the serial poll is

finished. A second serial poll will reflect the unlock

condition.

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The Lock-in Technique

A Measurement Example

The Lock-in technique is used to detect and

measure very small ac signals. A Lock-in amplifier

can make accurate measurements of small signals

even when the signals are obscured by noise

sources which may be a thousand times larger.

Essentially, a lock-in is a filter with an arbitrarily

narrow bandwidth which is tuned to the frequency

of the signal. Such a filter will reject most

unwanted noise to allow the signal to be

measured. A typical lock-in application may

require a center frequency of 10 KHz and a

bandwidth of 0.01 Hz. This 'filter' has a Q of 10⁶-

well beyond the capabilities of passive electronic

filters.

Suppose we wish to measure the resistance of a

material, and we have the restriction that we must

not dissipate very much power in the sample. If

the resistance is about 0.1Ω and the current is

restricted to 1 µA, then we would expect a 100 nV

signal from the resistor. There are many noise

signals which would obscure this small signal --

60Hz noise could easily be 1000 times larger, and

dc potentials from dissimilar metal junctions could

be larger still.

In the block diagram shown below we use a

1Vrms sine wave generator at a frequency w as

our reference source. This source is current

limited by the 1 MΩ resistor to provide a 1 µA ac

excitation to our 0.1Ω sample.

In addition to filtering, a lock-in also provides gain.

For example, a 10 nanovolt signal can be

amplified to produce a 10 V output--a gain of one

billion.

Two signals are provided to the lock-in. The

1VAC reference is used to tell the lock-in the exact

frequency of the signal of interest. The lock-in's

Phase-Lock Loop (PLL) circuits will track this input

signal frequency without any adjustment by the

All lock-in measurements share a few basic

principles. The technique requires that the

experiment be excited at a fixed frequency in a

relatively quiet part of the noise spectrum. The

lock-in then detects the response from the

experiment in a very narrow bandwidth at the

excitation frequency.

user. The PLL has two outputs, cos(w t) and

sin(w t).

The signal, Vs cos(w t+Ø), from the sample under

test is amplified by a high gain ac coupled

differential amplifier. The output of this amplifier is

multiplied by the PLL outputs in two Phase-

Sensitive Detectors (PSD1 and PSD2). This

multiplication shifts each frequency component of

Applications include low level light detection, Hall

probe and strain gauge measurement, micro-ohm

meters, C-V testing in semiconductor research,

electron spin and nuclear magnetic resonance

studies, as well as a host of other situations which

require the detection of small ac signals.

the input signal, w , by the reference frequency,

w , so that the output of the PSD's are given by:

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Vpsd1 = V cos(w t) cos(w t+Ø)

The full-scale sensitivity of 100 nV matches the

expected signal from our sample. The sensitivity

is calibrated to 1%. The instrument's output

stability also affects the measurement accuracy.

For the required dynamic reserve, the output

stability is 0.1%/°C. For a 10°C temperature

change we can expect a 1% error.

1/2 V cos[(w + w )t+Ø] +

1/2 V cos[(w - w )t+Ø]

Vpsd2 = Vs sin(w t) cos(w t+Ø)

1/2 V sin[(w + w )t+Ø] +

A front-end noise of 7 nV/√Hz will manifest itself

as a 1.2 nVrms noise after a 10 second low-pass

filter since the equivalent noise bandwidth of a

single pole filter is 1/4RC. The output will

converge exponentially to the final value with a 10-

second time constant. If we wait 50 seconds, the

output will have come to within 0.7% of its final

value.

1/2 V sin[(w - w )t+Ø]

The sum frequency component of each PSD is

attenuated by a low pass filter, and only those

difference frequency components within the low

pass filter's narrow bandwidth will pass through to

the dc amplifiers. Since the low pass filter can

have time constants up to 100 seconds, the lock-in

can reject noise which is more than .0025 Hz

away from the reference frequency input.

The dynamic reserve of 60 dB is required by our

expectation that the noise will be a thousand times

larger than the signal. Additional dynamic reserve

is available by using the bandpass and notch

filters.

For signals which are in phase with the reference

(¯=0¡), the output of PSD1 will be a maximum and

the output of PSD2 will be zero. If the phase is

non-zero, Vpsd1 ~ cos(Ø) and Vpsd2 ~ sin(°).

The magnitude output is given by,

A phase-shift error of the PLL tracking circuits will

cause a measurement error equal to the cosine of

the phase shift error. The SR530's 1° phase

accuracy will not make a significant contribution to

the measurement error.

2 1/2

R = {(V

)2 + (V

) }

~ V

psd1

psd2

Specifications for the Example Measurement

and is independent of the phase Ø. The phase

output is defined as

Specification

Value

Error

-1

Ø = - tan (V

/ V

)

psd2 psd1

Full Scale Sensitivity

Dynamic Reserve

Reference Frequency

Gain Accuracy

Output Stability

Front-End Noise

100 nV

60 dB

5 kHz

0.1%/°C

< 7 nV/√Hz 1.2%

> 10 S

Thus, a dual-phase lock-in can measure the

amplitude of the signal, independent of the phase,

as well as measure an unknown phase shift

between the signal and the reference.

Output Time Constant

Total RMS Error

0.7%

Understanding the Specifications

Shielding and Ground Loops

The table below lists some specifications for the

SR530 lock-in amplifier. Also listed are the error

contributions due to each of these items. The

specifications will allow a measurement with a 2%

accuracy to be made in one minute.

In order to achieve the 2% accuracy given in this

measurement example, we will have to be careful

to minimize the various noise sources which can

be found in the laboratory. (See Appendix A for a

brief discussion on noise sources and shielding)

While intrinsic noise (Johnson noise, 1/f noise and

alike) is not a problem in this measurement, other

noise sources could be a problem. These noise

sources can be reduced by proper shielding.

There are two methods for connecting the lock-in

to the experiment: the first method is more

convenient, but the second eliminates spurious

pick-up more effectively.

We have chosen a reference frequency of 5 kHz

so as to be in a relatively quiet part of the noise

spectrum. This frequency is high enough to avoid

low frequency '1/f' noise as well as line noise. The

frequency is low enough to avoid phase shifts and

amplitude errors due to the RC time constant of

the source impedance and the cable capacitance.

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appears on both the A & B inputs will not be

perfectly cancelled: the common mode rejection

ratio (CMRR) specifies the degree of cancellation.

For low frequencies the CMRR of 100 dB indicates

that the common mode signal is canceled to 1 part

in 10⁵, but the CMRR decreases by about 6

dB/octave (20 dB/Decade) starting at 1KHz. Even

with a CMRR of 10⁵, a 10 mV common mode

signal behaves like 100nV differential signal.

In the first method, the lock-in uses the A input in a

'quasi-differential' mode. Here, the lock-in detects

the signal as the voltage between the center and

outer conductors of the A input. The lock-in does

not force A's shield to ground, rather it is

connected to the lock-in's ground via a 10Ω

resistor. Because the lock-in must sense the

shield voltage (in order to avoid the large ground

loop noise between the experiment and the lock-

in) any noise pickup on the shield will appear as

noise to the lock-in. For a low impedance source

(as is the case here) the noise picked up by the

shield will also appear on the center conductor.

This is good, because the lock-in's 100 dB CMRR

will reject most of this common mode noise.

However, not all of the noise can be rejected,

especially the high frequency noise, and so the

lock-in may overload on the high sensitivity

ranges.

There are some additional considerations in

deciding how to operate the lock-in amplifier:

Dynamic Reserve (DR) is the ratio of the largest

noise signal that the lock-in can tolerate before

overload to the full-scale input. Dynamic reserve

is usually expressed in dB. Thus a DR of 60 dB

means that a noise source 1000 times larger than

a full scale input can be present at the input

without affecting the measurement of the signal. A

higher DR results in a degraded output stability

since most of the gain is DC gain after the phase

sensitive detector. In general, the lowest DR

which does not cause an overload should be used.

The Current Input has a 1 kΩ input impedance

and a current gain of 10⁶Volts/Amp. Currents

from 500 nA down to 100 fA full scale can be

measured. The impedance of the signal source is

the most important factor to consider in deciding

between voltage and current measurements.

For high source impedances, (>1 MΩ), and small

currents use the current input. Its relatively low

impedance greatly reduces the amplitude and

phase errors caused by the cable capacitance-

source impedance time constant. The cable

capacitance should still be kept small to minimize

the high frequency noise gain of the current

preamplifier.

Quasi-Differential Connection

The second method of connecting the experiment

to the lock-in is called the 'true-differential' mode.

Here, the lock-in uses the difference between the

center conductors of the A & B inputs as the input

signal. Both of the signal sources are shielded

from spurious pick-up.

For moderate source impedances, or larger

currents, the voltage input is preferred. A small

value resistor may be used to shunt the source.

The lock-in then measures the voltage across this

resistor. Select the resistor value to keep the

source bias voltage small while providing enough

signal for the lock-in to measure.

The Auto-Tracking Bandpass Filter has a Q of 5

and follows the reference frequency. The

passband is therefore 1/5 of the reference

frequency. The bandpass filter can provide an

additional 20 dB of dynamic reserve for noise

signals at frequencies outside the passband. The

filter also improves the harmonic rejection of the

lock-in. The second harmonic is attenuated an

additional 13dB and higher harmonics are

True-Differential Connection

With either method, it is important to minimize both

the common mode noise and the common mode

signal. Notice that the signal source is held near

ground potential in both cases. A signal which

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attenuated by 6 dB/octave more. You may wish to

use the bandpass filter and select a low dynamic

reserve setting in order to achieve a better output

stability. Since the processor can only set the

bandpass filter's center frequency to within 1% of

the reference frequency, this filter can contribute

up to 5° of phase shift error and up to 5% of

amplitude error when it is used. In addition, the

bandpass filter adds a few nanovolts of noise to

the front end of the instrument when it is in use.

In many servo applications, no output filtering is

needed. In this case, the SR530 may be modified

to reduce the output time constant to about 20 µS.

Contact the factory for details.

Noise measurement is a feature which allows

direct measurement of the noise density of the

signal at the reference frequency. This is a useful

feature to assess at what frequency you should

run your experiment.

Line Notch Filters should be used in most

measurement situations. The filters will reject

about 50 dB of line frequency noise (about a factor

of 300). If your reference frequency is one octave

away, then these filters will introduce a 5° phase

shift error, and a few percent amplitude error.

Their effect on your signal is negligible if your

reference frequency is more than two octaves

away.

Ratio Capability allows the lock-in's output to be

divided by an external voltage input. This feature

is important in servo applications to maintain a

constant loop gain, and in experiments to

normalize a signal to the excitation level.

Computer Interface allows a computer to control

and to record data from the instrument. This is the

single most important feature for extending the

lock-in's capabilities and it's useful lifetime.

Measurements which are impractical without a

computer become simple when a computer is

used to coordinate various parts of the

experiment.

The frequency range of the SR530 lock-in

amplifier extends from 0.5Hz to 100KHz. No

additional cards are required for the instrument to

cover its full frequency range. The SR530 can be

used to detect a signal at the reference frequency

or at twice the reference frequency to allow for

convenient measurement of the harmonic of the

signal.

The Internal Oscillator provides a reference

source for the lock-in. This allows the lock-in's

frequency to be set without an additional signal

generator. It also provides a sine wave to be used

as the signal stimulus in an experiment. The

frequency may be set via the computer interface

as well as manually.

Output Filters can have one pole (6 dB per

octave) or two poles (12 dB/octave). A two-pole

filter provides a signal to noise improvement over

a single-pole filter due to its steeper roll off and

reduced noise bandwidth. Single-pole filters are

preferred when the lock-in is used in a servo

system to avoid oscillation.

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this picket fence of frequencies would land on

some noise source, giving a spurious result. To

overcome this difficulty designers employed tuned

amplifiers or heterodyning techniques. All of these

'fix-ups' had drawbacks, including phase and

amplitude errors, susceptibility to drift, and card-

swapping to change frequencies.

SR530 Block Diagram

Several new concepts are used to simplify the

design of SR530 lock-in amplifier. In addition to

implementing recent advances in linear integrated

circuit technology, the instrument was designed to

take full advantage of its microprocessor controller

to improve performance and to reduce cost.

In contrast, the SR530 detects the signal by

mixing a reference sine wave in a precision analog

multiplier. Because of the low harmonic content of

this sine wave, the instrument is insensitive to

harmonics. This approach has eliminated the

difficulty, performance compromises, and cost of

the older techniques.

As an example of the new techniques used in the

SR530, consider the harmonic rejection problem.

Previously, lock-in amplifiers used a PLL with a

square wave output. The Fourier components of

the square wave created a serious problem -- the

lock-in would respond to signal and noise at f, 3f,

5f,.ad infinitum. Quite often, one component of

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and dc amplifiers will affect the stability and

dynamic reserve of the instrument. The output is

most stable when most of the gain is in the ac

amplifier, however, high ac gain reduces the

dynamic reserve.

The Signal Channel

The instrument has both current and voltage

inputs. The current input is a virtual ground, and

the 100 MΩ voltage inputs can be used as single-

ended or true differential inputs.

For the most demanding applications, the user

may specify how the system gain is partitioned.

However, with prefilters that are able to provide up

to 100 dB of dynamic reserve, and with chopper

stabilized dc amplifiers, most users will not be

concerned with just how the system gain is

allocated.

There are three signal filters. Each of these filters

may be switched 'in' or 'out' by the user. The first

filter is a line notch filter. Set to either 50 or 60 Hz,

this filter provides 50 dB of rejection at the line

frequency. The second filter provides 50 dB of

rejection at the first harmonic of the line frequency.

The third filter is an auto-tracking bandpass filter

with a center frequency tuned by the micro-

processor to the frequency of the signal. These

three filters eliminate most of the noise from the

signal input before the signal is amplified.

A Microprocessor Based Design

The instrument was designed to take full

advantage of its microprocessor controller. This

approach provides several key advantages...

A high-gain ac amplifier is used to amplify the

signal before entering the phase sensitive

detector. The high gain which is available from

this programmable amplifier allows the lock-in to

operate with a lower gain in its dc amplifier. This

arrangement allows high stability operation even

when used on the most sensitive ranges.

The instrument may be interfaced to a laboratory

computer over the RS232 and IEEE-488

interfaces. In addition to simply reading data from

the lock-in, the computer can control all of the

instrument settings with simple ASCII commands.

A key feature of the instrument is its four A/D

inputs and two D/A outputs. These analog I/O

ports may be used to read and supply analog

voltages to an experiment or measurement. All of

the input and output ports have a full-scale range

of ±10.24VDC with 2.5 mV resolution and 0.05%

accuracy.

Reference Channel

The processor controlled reference input

discriminator can lock the instrument's PLL to a

variety of reference signals. The PLL can lock to

sine waves or to logic pulses with virtually no

phase error. The PLL outputs are phase shifted

and shaped to provide two precision sine waves.

The two sine waves have 90° of phase shift

between them.

Computer control can eliminate set-up errors,

reduce tedium, allow more complete data

recording and post measurement analysis. Also,

the computer can play an active role in the data

acquisition by adjusting gains, etc., in response to

changing measurement conditions.

Phase Sensitive Detectors

The Phase Sensitive Detectors are linear

The microprocessor based design eliminates

many analog components to improve

multipliers which mix the amplified and filtered

signal with the reference sine waves. The

difference frequency component of the multipliers'

outputs are dc signals that are proportional to the

amplitude of the signal. The low-pass filters which

follow each multiplier can reject any frequency

components which are more than a fraction of a

Hertz away from the signal frequency.

performance, reliability, and reduce cost. For

example, the magnitude and phase outputs are

calculated by the microprocessor instead of using

an analog vector summer. This eliminates the

temperature drifts and inaccuracies associated

with nonlinear analog circuits and greatly reduces

the number of parts. Each unit is computer

calibrated at the factory, and calibration constants

are placed in the instrument's read-only memory.

The SR530 has only one-fifth of the analog

trimming components that are found in older

designs.

DC Amplifiers and System Gain

Dc amplifiers amplify and offset the outputs of the

two low pass filters. The total system gain is the

product of the ac and dc amplifier gains. The

partitioning of the system gain between these ac

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to the left hand transistor but with the opposite

sign. Resistors R112 and R110 attenuate the

fed back signal from the output of U101 resulting

in a differential input, single ended output, fixed

gain of 10 amplifier. P101 adjusts the current

balance between the two transistors and

therefore their gain match and common mode

rejection.

Circuit Description

Introduction

The SR530 Lock-in amplifier is an integrated

instrument combining state of the art analog design

with advanced microprocessor based control and

interfaces. This discussion is intended to aid the

advanced user in gaining a better understanding of

the instrument.

The output of the pre-amp is scaled by resistors

R119-R122 and analog switch U103 which

make up a 1-2-5-10 attenuator. The signal is

then amplified by 2/2 U102. Input overload is

sensed through diodes D101-D104.

The SR530 has eight main circuit areas: the signal

amplifier, the reference oscillator, the demodulator,

the analog output and controls, the front panel, the

microprocessor, the computer interfaces, and the

power supplies. With the exception of the front

panel, the quadrature oscillator and demodulator,

and a few pieces of hardware, the entire lock-in is

built on a single printed circuit board. Each section

is isolated from the others as much as possible to

prevent spurious signal pickup. To aid in the

location of individual components, the first digit (or

first two digits of a four digit part number) of each

part number generally refers to the schematic sheet

number on which it occurs. To help find the part on

the circuit board, the parts list includes a location on

the circuit board for each component. Parts with a

four-digit part number beginning with 10,11, or 12

are found on the quadrature detector plug-in board

located in the center of the main circuit board. Part

numbers beginning with 6 refer to parts on the front

panel.

Current Amplifier

When the input selector is set to current, the

input to the pre-amp comes from the output of

the current to voltage converter, 1/2 U102.

U102 is a low voltage-noise bipolar op amp.

Q102 serves as an input buffer to provide low

current-noise to the input. The op amp always

maintains a null at the gates of Q102 thus

providing an input impedance of 1KΩ (R128).

The input current is converted to a voltage by

R135 and the op amp. Q103 bootstraps out the

summing junction capacitance of Q102.

Notch Filters

U107 is a high Q, line frequency, notch filter

which can be switched in and out by analog

switch 1/4 U106. The frequency and depth of

the filter can be adjusted with P102 and P103.

Resistors R146-R149 and switch U108 make up

a selectable attenuator. U118 is a line

frequency 2nd harmonic notch filter selected by

2/4 U106. P104 and P105 adjust the frequency

and depth. The second notch filter has a gain of

3 and its output is scaled by U110 and resistors

R156-R159. The signal then takes two paths; to

inverting amplifier U111 and to the input of the

tracking bandpass filter. U111 has the same

gain as the bandpass filter. The output of either

U111 or the bandpass filter is selected by 3/4

U112 and 4/4 U106 and amplified by U113.

U114 and U115 provide a last stage of gain and

scaling and the final output is ac coupled and

buffered by 4/4 U208.

Signal Amplifier

Assuming the input selector switch is set to a voltage

input, the signal is coupled in through capacitors

C101 and C102. The input impedance is set by the

100 MΩ resistors R101 and R102 over the operating

frequency range. Note that R103 isolates the signal

shields from the instrument ground forcing the return

signal current back along the cable shields. The

signal is then applied differentially to the gates of

Q101. Q101 is a low noise dual JFET. The drain

current through R109 is kept constant by 2/2 U101.

The other half of U101 maintains a virtual null

between the drains of the two transistors and thus

an identical current flows through R110. Any input

that would cause a differential between the two

drains is amplified by 1/2 U101 and fed back via

R112 in such a way as to reduce that differential.

Since the two transistors are at equal and constant

currents, their gate-source potentials are constant.

Thus, the fed back signal which appears at the

source of the right hand transistor exactly matches

the input . Likewise, this signal will match the input

Bandpass Filter

The bandpass filter is a three op amp state-

variable active filter. 3/4 of U201 make up the

three op amps of the standard filter. U203,

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U204, and U205 are analog switches which select

the feedback capacitors for the 5 decades of

operation. The two halves of U202 are matched

transconductance amplifiers operating as

phase or quadrature relationship between the

two VCO's. Thus, the output of the second VCO

can be shifted from -5 to 185 deg from the

reference.

programmable, voltage controlled, current sources

which take the place of the normal, frequency

setting, resistors. A voltage proportional to the

reference frequency is converted into a current by

1/4 U208 and Q201. This current programs the

effective "resistance" of the two transconductance

amplifiers and thus, tunes the center frequency of

the filter to follow the reference. The output of the

filter is buffered by 4/4 U201. The two remaining op

amps in U208 are used to detect signal overloads

throughout the amplifier chain.

The triangle output is divided by R363 and R362

before reaching transconductance amplifier 2/2

U322. The amplitude of the triangle input to this

amplifier is enough to just saturate the input and

provide a sine wave output. 2/2 U325 then

amplifies the sine wave before it goes to the

demodulator. U324 is a comparator which

generates a square wave in-phase with the sine

output. U326 divides the frequency of the

square wave by eight and 2/2 U327 selects the

frequency of the square wave chopper.

Reference Oscillator

The square wave output of U322 serves as the

reference to the quadrature oscillator PLL. This

PLL is identical to the triangle oscillator, sine

wave shaper described above. U1004 detects

the zero-crossings of the triangle wave to feed

back to the phase comparator, U1002. This

ensures that the quadrature triangle wave is 90

deg out of phase from the first sine wave. The

quadrature triangle is shaped into a sine wave

by 2/2 U1009 and amplified by 2/2 U1014.

U1012 is a comparator which generates a

square wave in-phase with the quadrature sine

wave. U1013 divides the frequency of the

square wave by eight and 1/2 U1011 selects the

frequency of the square wave chopper.

The reference input signal is ac coupled and

buffered by U301. R378 isolates the reference

shield from the lock-in ground to prevent ground loop

currents. 1/2 U303 switches the polarity of the

reference reaching comparator U304. U305 is a

retriggerable one-shot whose output indicates a no

reference condition if no comparator pulses are

generated for three seconds.

U309 is a dual transconductance amplifier in a

triangle VCO configuration. U310 selects the

integrating capacitor depending on the frequency

range. The VCO frequency is determined by the

programming current through R318 and therefore by

the output voltage of U308. C306 is the phase-

locked loop low pass filter which is buffered by

U308. U307 is a programmable current source used

to charge and discharge C306. The amount of

current available to U307 is determined by the VCO

control voltage, thus, the tracking rate of the VCO is

proportional to the VCO frequency. The triangle

output is compared to a constant voltage by U314.

1/2 U313 and 1/2 U312 select f or 2f operation. This

signal is fed back to the phase detector U306 to be

compared with the reference output of U304. U315

compares the triangle output with a variable voltage

to generate a square-wave signal phase-shifted from

the reference. The range of this fine phase shift

control is -5 to 95 degrees.

Demodulator and Low Pass

Amplifier

Amplifier U402 and switch U401 select the

polarity of the reference sine wave. This allows

phase shifts up to 360 degrees from the

reference input. The sine wave is ac coupled by

U403 and inverted by U404. U405 selects

alternating polarities of the sine wave at the

chopper frequency, f/2 or f/16. This chopped

sine wave is then multiplied by the output of the

signal amplifiers by the analog multiplier U406.

The synchronous output of the multiplier that

corresponds to the in-phase signal is a square

wave at the chopper frequency. The output is

ac coupled by U407 to remove the dc offset of

the multiplier. U408 inverts the signal and U405

chops the square wave to recover a dc output.

U409 buffers the chopper output before the first

low pass time constant. Op amps U416 and 2/2

U402 make up the first low pass amplifier with

relays U411-U415 and U417 selecting the time

constant. The second low pass amplifier is

The output of U315 serves as the reference to a

second phase-locked loop. This second PLL uses a

similar proportional tracking triangle VCO.

Comparator U329 looks at the square wave output

of the VCO while comparator U328 detects the zero

crossings of the triangle output. 1/2 U327 selects

one these comparators to feed back to the phase

detector, U316. Since the square and triangle

outputs are in quadrature, U327 selects either an in-

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U419. Analog switch U418 selects the time constant

and gain. The full scale output of U418 is 5 volts.

used to program the band pass filter and the

reference oscillator phase shift. One output is

subtracted from the lock-in output in U508 to

provide a variable offset and another is the rms

noise output. The remaining two outputs

generate the magnitude and phase output

voltages.

The quadrature demodulator and low pass amplifiers

are identical to that described above. The

quadrature detector output is provided by U1119.

Analog Output and Control

Expand

The dc output of the demodulator/low pass

amplifiers is passed to the reference input of

multiplying DAC U502. The DAC is programmed

with the appropriate attenuation to calibrate the

overall gain of the lock-in. Every gain setting in each

dynamic reserve is calibrated independently and the

proper attenuations are stored in the unit's ROM.

3/4 U511 and 4/4 U1202 are the expand

amplifiers. They provide a selectable gain of 10

to the channel 1 and 2 outputs just before the

output buffers.

Front Panel

The quadrature output is calibrated by DAC U1201.

Amplifiers U1204 and U1205 buffer the two

demodulator outputs to drive the X and Y BNC's.

There are 71 led's on the front panel controlled

by 9 serial-in, parallel-out shift registers. 8 of the

shift registers are written to simultaneously and

the 9th is written separately. 8 consecutive write

operations are required to set the LED's in each

case. The liquid crystal displays are managed

by the display controllers, U6101, U6102, and

U6103. Exclusive-or gates U6104, U6105 and

U6106 drive the left over segments. Latches

U6107 and U6108 provide the logic bits for

these extra segments as well as the keyboard

row strobes. U6109 reads the switch closures

as the rows are scanned.

A/D's

Analog multiplexer U504 selects the signal to be

digitized by the microprocessor. This signal can be

either the lock-in's in-phase or quadrature output or

one of the four independent analog inputs buffered

by U501. These general purpose inputs are located

on the rear panel of the instrument. The selected

signal is sampled and held on capacitor C502 and

buffered by 4/4 U508. The A/D conversion is done

by successive approximation using comparator

U514 to compare the sampled and held signal with

known outputs of U505, a 12 bit DAC with a

precision reference. Note that the output of U506,

an 8 bit DAC is summed with the output of U505.

This 8 bit DAC corrects for offset errors which can

accumulate as analog voltages pass through

buffers, S/H amps, and comparators. These offsets

are measured after each unit is manufactured, and

values to compensate for these offsets are placed in

the unit's ROM. The polarity of the offset-corrected

12 bit DAC is set by 2/4 U511 and the SIGN bit

yielding 13 bits of resolution from -10.24 to +10.24

volts.

Microprocessor Control

The microprocessor, U701, is a Z80A CPU

clocked at 4 MHz. 16K bytes of firmware are

stored in the ROM, U702. U703 is a 2K byte

static RAM, backed-up by a lithium battery. A

power-down standby circuit, Q701, preserves

the RAM contents when the power is turned off.

The battery has a life of 5-10 years. The CPU

has power-up and power-down resets to prevent

erroneous execution during turn-on or short

sags in the line voltage.

U704 is a 3-channel counter. One channel

generates the baud rate for the RS232 interface

while the other two are used to measure the

frequency or period of the reference oscillator.

U709 provides a gate pulse to counter 0.

Multiplexer U708 selects whether the gate is a

single period of the reference (period

measurement) or a gate of known duration

(frequency measurement). Counter 1 is a

programmable divide by N counter whose output

is either counted for one period of the reference,

D/A's

In addition to providing reference voltages for A/D

conversion, the DAC output voltage may be

multiplexed by U507 to one of eight sample and hold

amplifiers which provide analog output and control

voltages. The microprocessor refreshes each S/H

amplifier every few milliseconds to prevent droop.

Two of these outputs are available as general

programmable outputs on the rear panel. Two are

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or, generates the gate pulse during which reference

pulses are counted.

Internal Oscillator

The internal oscillator is on a small circuit board

attached to the rear panel of the instrument.

Local regulators, Q1 and Q2, provide power to

the board. The VCO input is internally pulled up

by R12. This pulls the VCO input to 10V when

the VCO input is left open. 2/4 U1 translates the

VCO input voltage to provide a negative control

voltage to U2, the function generator. P3

adjusts the VCO calibration. U2 is a sine wave

generator whose frequency range is selected by

the VCO Range switch and capacitors, C4-C6.

P2 adjusts the sine wave symmetry at low

frequencies. 4/4 U1 buffers the output of U2.

P1 adjusts the amplitude of the output sine

wave. The output amplitude on the SIne Out is

selected by the amplitude switch. The output

impedance is 600 Ω.

I/O addresses are decoded by U705, U706, and

U707. The microprocessor controls the lock-in

functions through I/O ports U714-U721. U713

generates an interrupt to the CPU every 4 msec to

keep the microprocessor executing in real time.

RS232 Interface

The RS232 interface uses an 8251A UART, U801,

to send and receive bytes in a bit serial fashion. Any

standard baud rate from 300 to 19.2K baud may be

selected with the configuration switches. The X16

transmit and receive clock comes from counter 2 of

U704. The RS232 interface is configured as DCE so

that a terminal may be connected with a standard

cable. When a data byte is received by the UART,

the RxRDY output interrupts the CPU to prevent the

data from being overwritten.

GPIB Interface

The interface to the GPIB is provided by U802, an

MC68488 General Purpose Interface Adapter

(GPIA). The GPIB data and control lines are

buffered by drivers U808 and U811. Because the

GPIA uses a 1 MHz clock, wait states are provided

by U805 to synchronize I/O transactions with the 4

MHz CPU. The GPIA interrupts the CPU whenever

a GPIB transaction occurs which requires the CPU’s

response. (The GPIB address is set by switch bank

SW1.)

Power Supplies

The line transformer provides two outputs, 40VAC

and 15VAC, both center tapped. The transformer

has dual primaries which may be selected by the

voltage selector card in the fuse holder. The 15VAC

is rectified by diode bridge BR2 and passed to 5V

regulator U909. The output of U909 powers the

microprocessor and its related circuitry. The 40VAC

output is half-wave rectified by BR1 and regulated by

U901 and U902 to provide +20V and -20V. These

two dc voltages are then regulated again by 15V

regulators U903-U908. Each 15V regulator powers

a separate section of the lock-in to reduce coherent

pick up between sections. U911 and U912 provide

plus and minus 7.5V and U910 generates +5V for

the analog circuits.

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minimize the 500 Hz output. Adjust P403 at location

C2 to minimize the 30 Hz output.

Calibration and Repair

Now set the both time constants to 1S. Adjust P404

at location F4 to zero the output. This adjustment

has a range of 20% of full scale on the HIGH

dynamic reserve setting. (2% on NORM and 0.2%

on LOW). This zeroes the DC output of Channel 1

on all dynamic reserve ranges.

This section details calibration of the instrument.

Calibration should be done only by a qualified

electronics technician.

********* WARNING *********

The calibration procedure requires adjusting the

instrument with power applied and so there is a

risk of personal injury or death by electric shock.

Please be careful.

Now connect the scope to the CHANNEL 2

OUTPUT. Set the PRE TIME CONSTANT to 1mS

and the POST TIME CONSTANT to NONE. Adjust

P1102 to minimize the 500 Hz output. Adjust P1103

to minimize the 30 Hz output. Set both time

constants to 1S. Adjust P1104 to zero the output.

All three potentiometers are located on the plug-in

board in the center of the main circuit board.

Most of the calibration parameters are

determined by a computer aided calibration

procedure after burn-in at the factory. These

calibration parameters are quite stable and so

will not need to be adjusted. Calibration

parameters which may need field adjustment are

detailed below.

Replace the top panel.

Amplifier and Filter Adjustments

Multiplier Adjustments

This section describes how to adjust the Common

Mode Rejection and Line notch filter frequencies.

An oscilloscope and a signal generator which can

provide an accurate line frequency and twice line

frequency sine wave are required.

On the HIGH dynamic reserve setting, there can

be some reference frequency feedthrough. This

section describes how to null this unwanted

output.

Allow the unit to warm up for about 1 hour.

This adjustment requires an oscilloscope and a

signal generator which can provide a 500Hz

reference signal.

Reset the unit by turning it off and back on while

holding the LOCAL key down.

Allow the unit to warm up for about 1 hour.

Remove the four screws holding down the top panel.

Slide the panel back about halfway.

Reset the unit by turning it off and back on while

holding the LOCAL key down.

CMRR

Select voltage input A and connect a 50 1/2

terminator or shorting plug to the A input BNC

connector. Connect the 500 Hz reference signal

to the reference input. Set the SENSITIVITY to

1mV and the DYN RES to HIGH. The PRE

TIME CONSTANT should be set to 1mS and

the POST TIME CONSTANT to NONE.

Connect the scope to the CHANNEL 1 OUTPUT

on the front panel. Set the scope to 2V/div and

5mS/div. Externally trigger the scope using the

reference input signal.

Set the reference frequency to 100 Hz. It is

convenient to use the SYNC output of the signal

generator as the reference input if it is available.

Connect the sine output of the signal generator to

the A input and set the input selector to A. With the

SENSITIVITY at 100mV, adjust the amplitude of the

input signal to 100 mV (full scale).

Now set the input selector to A-B and connect the

signal to both the A and B inputs. Set the

SENSITIVITY to 20µV, the DYN RES to NORM and

the BANDPASS filter IN. Connect the scope to the

SIGNAL MONITOR output on the rear panel. Set

the scope to AC coupled, 0.2V/div, and 10mS/div.

Externally trigger the scope using the reference input

signal.

After about 90 seconds, the scope display

should show a 500 Hz sine wave on a 30 Hz

(500/16 Hz) square wave. Remove the four

screws holding the top panel on. Slide the top

panel back about half way. Using a small

screwdriver, adjust P402 at location D2 to

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The CMRR is adjusted by the single turn

potentiometer located at A1 under the single

hole at the front of the signal shield. (The shield

is the aluminum box on the left side of the main

board). Using a small screwdriver, carefully

adjust the potentiometer to minimize the 100 Hz

output on the scope. Set the DISPLAY to R,Ø

and the sensitivity to 5µV and minimize the R

output on the Channel 1 meter.

Replacing the Front-End Transistors

Both the voltage and current front end transistors

(Q101 and Q102) are 2N6485 (IMF6485) dual

JFETS. These transistors are selected at the factory

to meet the noise specifications.

This section outlines their replacement procedure in

the event that they become damaged during use.

1) Remove the AC power cord from the unit.

Notch Filters

2) Remove top and bottom panels.

Set the reference frequency to 60.0 Hz (50.0

Hz). It is convenient to use the SYNC output of

the signal generator as the reference input if it is

available. Connect the sine output of the signal

generator to the A input and set the input

selector to A. With the SENSITIVITY at 100mV,

adjust the amplitude of the input signal to 100

mV (full scale).

3) Release the signal shields by removing the four

screws which hold it onto the circuit board. Be

careful not to lose the nuts. Carefully slide the

shields back and then lift them out.

4) The input transistors are located on the main

board, just behind the input selector switch.

Q101 is the voltage (A, A-B) front end, and

Q102 is the current (I) front end. Desolder and

replace the appropriate transistor.

Set the LINE NOTCH to IN, the SENSITIVITY to

10mV, and the DYN RES to LOW. Connect the

scope to the SIGNAL MONITOR output on the

rear panel. Set the scope to AC coupled,

0.2V/div, 10mS/div. Trigger the scope externally

using the reference input signal.

5) Replace the signal shields. Be careful to check

that the shields do not touch any circuit board

traces around their edges.

The LINE NOTCH frequency and depth are

adjusted by the pair of 20 turn potentiometers

located under the middle two holes in the signal

shield (row 4 on the circuit board). Using a

small screwdriver, carefully adjust one pot until

the line output on the scope is minimized. Then

adjust the other pot until the output is minimized.

Iterate between the two pots until there is no

further improvement. Set the SENSITIVITY to

5mV, 2mV, and 1mV, repeating the adjustments

at each sensitivity.

6) Replace the top and bottom panels.

7) If Q101, the voltage front end has just been

replaced, the Common Mode Rejection needs to

be readjusted using the procedure described in

the Amplifier Adjustments section.

Repeat this procedure using a reference

frequency of 120.0 Hz (100.0 Hz) and the

LINEX2 NOTCH filter. The LINEX2 NOTCH is

adjusted by the pair of 20 turn potentiometers

located under the back two holes in the signal

shield (row 5 on the circuit board).

Replace the top panel.

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And Others. Other noise sources include flicker

noise found in vacuum tubes, and generation and

recombination noise found in semiconductors.

Appendix A:

Noise Sources and Cures

All of these noise sources are incoherent. Thus, the

total noise is the square root of the sum of the

squares of all the incoherent noise sources.

Noise, random and uncorrelated fluctuations of

electronic signals, finds its way into experiments

in a variety of ways. Good laboratory practice

can reduce noise sources to a manageable

level, and the lock-in technique can be used to

recover signals which may still be buried in

noise.

Non-Essential Noise Sources

In addition to the "intrinsic" noise sources listed

above there are a variety of "non-essential" noise

sources, i.e. those noise sources which can be

minimized with good laboratory practice. It is

worthwhile to look at what might be a typical noise

spectrum encountered in the laboratory

environment:

Intrinsic Noise Sources

Johnson Noise. Arising from fluctuations of

electron density in a resistor at finite

temperature, these fluctuations give rise to a

mean square noise voltage,

V = ∫4kT Re[Z(f)] df = 4kTR ∆f

where k=Boltzman's constant, 1.38x10-23J/°K; T

is the absolute temperature in Kelvin; the real

part of the impedance, Re[z(f)] is the resistance

R; and we are looking at the noise source with a

detector, or ac voltmeter, with a bandwidth of ∆f

in Hz. For a 1MΩ resistor,

2 1/2

(V )

= 0.13 µV/√Hz

To obtain the rms noise voltage that you would

see across this 1M½ resistor, we multiply

0.13µV/√Hz by the square root of the detector

bandwidth. If, for example, we were looking at

all frequencies between dc and 1 MHz, we

would expect to see an rms Johnson noise of

2 1/2

1/2

(V )

= 0.13 µV/√Hz*(10 Hz)

= 130 µV

Noise Spectrum

'1/f Noise'. Arising from resistance fluctuations

in a current carrying resistor, the mean squared

noise voltage due to '1/f' noise is given by

Some of the non-essential noise sources appear in

this spectrum as spikes on the intrinsic background.

There are several ways which these noise sources

work their way into an experiment.

2 2

= A R I ∆f/f

-11

where A is a dimensionless constant, 10

for

carbon, R is the resistance, I the current, ∆f the

bandwidth of our detector, and f is the frequency

to which the detector is tuned. For a carbon

resistor carrying 10 mA with R = 1k, ∆f = f = 1Hz,

we have

= 3 µVrms

noise

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Capacitive Coupling. A voltage on a nearby

piece of apparatus (or operator) can couple to a

detector via a stray capacitance. Although

Inductive Coupling. Here noise couples to the

experiment via a magnetic field:

may be very small, the coupled in noise

stray

may still be larger than a weak experimental

signal.

Inductive Noise Coupling

A changing current in a nearby circuit gives rise to a

changing magnetic field which induces an emf in the

loop connecting the detector to the experiment.

Capacitive Noise Coupling

To estimate the noise current through C_strayinto

the detector we have

(emf = dØ_B/dt.) This is like a transformer, with the

experiment-detector loop as the secondary winding.)

dV = jwC

stray

stray noise

Cures for inductively coupled noise include:

1) removing or turning off the interfering noise

source (difficult to do if the noise is a broadcast

station),

where a reasonable approximation to C

can

stray

be made by treating it as parallel plate capacitor.

Here, w is the radian frequency of the noise

2) reduce the area of the pick-up loop by using

twisted pairs or coaxial cables, or even twisting the 2

coaxial cables used in differential hook-ups,

source (perhaps 2 * π * 60Hz ), V

is the

noise

noise voltage source amplitude (perhaps 120

VAC). For an area of A = (.01 m)2 and a

distance of d = 0.1m, the 'capacitor' will have a

value of 0.009 pF and the resulting noise current

will be 400pA. This meager current is about

4000 times larger than the most sensitive

current scale that is available on the SR510

lock-in.

3) using magnetic shielding to prevent the magnetic

field from inducing an emf (at high frequencies a

simple metal enclosure is adequate),

4) measuring currents, not voltages, from high

impedance experiments.

Cures for capacitive coupling of noise signals

include:

1) removing or turning off the interfering noise

source,

2) measuring voltages with low impedance

sources and measuring currents with high

impedance sources to reduce the effect of i

stray

3) installing capacitive shielding by placing both

the experiment and the detector in a metal box.

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Resistive Coupling (or 'Ground Loops').

Currents through common connections can give

rise to noise voltages.

Microphonics provides a path for mechanical noise

to appear as electrical noise in a circuit or

experiment. Consider the simple circuit below:

The capacitance of a coaxial cable is a function of its

geometry so mechanical vibrations will cause the

cable capacitance to vary with time. Since C=Q/V,

we have

C dV + V dC = dQ = i

Resistive Coupling

Here, the detector is measuring the voltage

across the experiment, plus the voltage due to

the noise current passing through the finite

resistance of the ground bus. This problem

arises because we have used two different

grounding points which are not at exactly the

same potential. Some cures for ground loop

problems include:

so mechanical vibrations will cause a dC/dt which in

turn gives rise to a current i, which will affect the

detector. Ways to eliminate microphonic signals

include:

1) eliminate mechanical vibrations,

2) tie down experimental cables so they will not

sway to and fro,

1) grounding everything to the same physical

point,

3) use a low noise cable that is designed to reduce

microphonic effects.

2) using a heavier ground bus to reduce the

potential drop along the ground bus,

Thermocouple Effect. The emf created by dissimilar

metal junctions can give rise to many microvolts of

dc potential, and can be a source of ac noise if the

temperature of the junction is not held constant.

This effect is large on the scale of many low level

measurements.

3) removing sources of large currents from

ground wires used for small signals.

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data, must also be connected correctly at the

terminal end. If the terminal responds to a control

line, it will believe that the SR530 is not ready to

accept data (because the line is not passed in this

example) and will therefore not send any data.

Appendix B:

Introduction to the RS232

The 'RS232' is a standard for bit serial

asynchronous data communication. The

standard defines the format for data

transmission, the electrical specifications for the

signal levels, and the mechanical dimensions of

connectors.

CASE 2 - RS232 with Control Lines.

Despite the definition of a standard, there are so

many permutations of control lines, data

formats, and transmission speeds, that getting

two RS232 devices to communicate usually

requires some work.

The data lines are the same as in Case 1. In

addition to the data lines, there are two control lines

used:

In this section, we will provide some basic

information to aid you in connecting your RS232

device to the SR530 Computer Interface.

CTS - Pin 5

"Clear to send" is a signal asserted by the DCE to

tell the DTE that the DCE is ready to receive data.

CASE 1 - The Simplest Configuration.

DTR - Pin 20

"Data Terminal Ready" is a signal asserted by the

DTE to tell the DCE that the DTE is ready to receive

data.

The SR530 responds to the control lines as follows:

1) If the lines are not connected, the SR530

assumes that you are ready to receive data.

In this case, one wire is used to send data from

device A to device B and another wire is used to

send data from device B to device A. Notice

that pin 2 is an output on device A and an input

on device B. (It is good practice to run the

ground, pin 7, between the devices as well).

The RS232 defines two types of devices; DTE

(Data Terminal Equipment) and DCE (Data

Communications Equipment.) An RS232 port

on a computer may be either a DTE or DCE but

nearly every terminal with an RS232 port is a

DTE. RS232 ports on a computer which are

intended to connect to a modem, such as the

COM1: port on the IBM PC, are DTE. The

SR530 is configured as DCE, and so it may be

directly connected to ASCII terminals and to the

COM: ports on IBM PC's and compatibles.

2) Data will not be transmitted from the SR530 if the

DTR line (pin 20) is low. This is useful in the case

when your program is not yet ready to receive data.

If data transmission is not suspended, then data

may be overwritten in your computer's UART (as it is

not being retrieved by the program and so will be

lost.) When this happens, the 'over-run' flag will be

set in your computer's UART and it may be

recognized by the operating system, generating an

error message such as "I/O Device Error" (See the

"W" command in the SR530 Command List for

another way to slow data transmission.)

Baud Rate

The RS232 baud rate of the SR530 is switch

selectable from 300 to 19.2K baud (see

As an example, consider connecting an RS232

ASCII computer terminal to the SR530 using a 2

wire link. The terminal is a DTE and the SR530

is a DCE. To operate correctly, the SR530 and

the terminal must have the same settings for

baud rate, parity, and number of stop bits. The

control lines in the RS232 Standard, which are

used to indicate that a device is ready to accept

configuration switch setting in the front of this

manual.) 19.2K baud means that data is transmitted

at 19,200 bits/second. With one start bit, 2 stop bits,

8 data bits, and no parity bits, each ASCII character

requires 573 µsec to be transmitted (11bits/19.2K

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baud.) The typical data string 5.1270<cr> has 7

characters, requiring 4 msec to be sent.

letter 'A', which has the ASCII code 41H (0100

0001), would appear as follows:

If a parity option was selected, the parity bit would

be sent after the 8th data bit, but before the first stop

bit.

Stop Bits

Generally, selection of 2 stop bits will result in

fewer data transmission errors.

Final Tip

When you are trying to get the RS232 to work with

your computer, it is helpful to be able to 'eavesdrop'

on the RS232 data lines going between the SR530

and the computer. This can be done with an ASCII

RS232 terminal and the following connector:

Parity

The Parity bit provides a check against faulty

data transfer. It is not commonly used in local

data transmission environments. If the parity

option is selected, the SR530 will transmit 8 data

bits and a parity bit, however, no parity check of

incoming data is done.

Voltage Levels

The RS232 uses bipolar voltage levels:

To test the connector, place the hook clip on pin 2 of

the same connector (shorting pin 2 to pin 3.) Now,

when you type at the terminal keyboard, data

transmitted from pin 2 is received at pin 3 and

displayed on the terminal screen. To use as a

debugging tool, attach the hook clip to either pin 2 or

pin 3 of the RS232 cable on the SR530 to show

either data sent from the Computer or the SR530.

The baud rate, parity, and stop bits of the terminal

must match those of the SR530 and the computer.

If your terminal has a mode which will display control

characters (such as carriage returns and line feeds)

it is helpful to operate in that mode.

The control lines use positive logic. For

example, the DCE tells the DTE that it is clear to

send (CTS) by placing > +3 VDC on pin 5 of the

interface. Similarly, the DTE can tell the DCE

that it is not ready by placing -3 VDC on pin 20

(DTR) of the interface.

A variant of the 'eavesdropping' approach is

The data lines, pins 2 and 3, use negative logic.

A 'zero' bit is represented by a positive voltage

and a 'one' bit is represented by a negative

voltage. A start bit is a positive voltage and a

stop bit is a negative voltage. Data is

diagrammed below:

With this cable arrangement, the ASCII terminal can

listen to the data passing in both directions. The

only drawback is that the terminal will display

garbled data if both devices transmit data at the

same time.

transmitted with the least significant bit first. The

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Data Bus: There are eight data lines which use

negative logic and pass the bits of each byte in

parallel.

Appendix C:

Introduction to the GPIB

General Interface Lines: These five lines operate

independently of the handshake lines and use

negative logic.

The IEEE-488 Standard specifies the voltage

levels, handshake requirements, timing,

hardware details, pinout and connector

dimensions for a 16 line, bit parallel bus. Many

instruments may be connected in series to

communicate over the same cable. Because

the bits are passed in parallel, the GPIB is faster

than the RS232.

1) The EOI (End or Identify) line is used by the talker

to designate the end of message.

2) The SRQ (Service Request) line is used by any

device to ask for service. The controller can serial

poll each device (each device returns an 8 bit status

byte) to determine who needs attention. It can also

do a parallel poll using the EOI and ATN lines where

each device is assigned a single data line.

The controller (generally your computer)

coordinates data transfer on the bus by

designating all participating instruments

(including itself) as either a talker or a listener.

Listeners can receive data placed on the bus by

the Talker. Devices can have the capacity to

operate in either mode. The address of each

device is set by switches in the device and must

be between 0 and 30.

3) The ATN (Attention) line makes both talkers and

listeners accept information and passes control of

the DAV line to the controller. This line is used by

the controller to identify talkers and listeners through

their addresses.

Bus Description

4) The REN (Remote Enable) line changes the

status of an instrument from local to remote.

Byte Transfer Control Group. This consists of

3 negative logic lines that implement the GPIB

handshaking. The NRFD (Not Ready For Data)

line is held low by any designated listener who is

not ready to accept data. When every listener is

ready, the line goes high and the talker may

release data to the bus. After data is on the bus,

the talker pulls the DAV (Data Valid) line down.

At this point, each listener retrieves the data.

Before and during the retrieval of the data, the

listener holds the NDAC (No Data Accepted) line

down. When every listener has received the

data, the NDAC line goes high, allowing the

talker to release the DAV line high. Finally, the

listener pulls down the NDAC line until another

transfer is initiated.

5) The IFC (Interface Clear) line clears the bus of all

data and activity.

Though GPIB is a very powerful interface, strict

protocol must be observed for it to operate

successfully.

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Appendix D:

Program Examples

All of the program examples which follow do the

same thing, only the computer, language, or

interface is changed. The programs read the

Channel 1 and 2 Outputs and write the results to

the computer screen. In addition, the X6 analog

output port is ramped from 0 to 10V.

Program Example 1:

IBM PC, Basic, via RS232

In this example, the IBM PC's ASYNC port (known

as COM1: or AUX: to DOS users) will be used to

communicate with the SR530. Only two wires

between the IBM PC's ASYNC port and the

SR530 are needed (pins #2 & #3 of the RS232),

but pins 5,6,8 and 20 should be connected

together on the connector at the IBM end.

10 ′ EXAMPLE PROGRAM TO READ THE SR510 OUTPUT AND RAMP THE X6 ANALOG OUTPUT

20 ′ USING IBM PC BASICA AND THE COM1: RS232 PORT.

30 ′ THE RAMP ON X6 CAN BE WATCHED BY SETTING THE SR530 DISPLAY TO A/D.

40 ′

50 ′

60 ′ ON THE REAR PANEL OF THE SR530, SET SWITCH #1 OF SW2 DOWN

70 ′ AND ALL OTHER SWITCHES IN SW2 UP. (9600 BAUD, NO PARITY)

80 ′

90 OPEN ″COM1:9600,N,8,2,CS,DS,CD″ AS #1

100 ′ SET UP COM1: PORT TO 9600 BAUD, NO PARITY, 8 DATA BITS, 2 STOP BITS,

110 ′

120 ′

130 ′

IGNORE CTS (CLEAR TO SEND), DSR (DATA SET READY),

AND CD (CARRIER DETECT).

140 PRINT #1, ″ ″ ‘CLEAR UART BY SENDING SPACES

150 PRINT #1, ″Z″ ′RESET SR530

160 FOR I = 1 TO 200: NEXT I

′WAIT FOR RESET TO FINISH

170 ′

180 X = 0

′INIT X6 OUTPUT TO ZERO

190 ′

200 PRINT #1, ″Q1″

210 INPUT #1,V1

220 PRINT #1, ″Q2″

230 INPUT #1,V2

240 ′

′READ OUTPUT

′INTO V1

′READ OUTPUT

′INTO V2

250 PRINT ″CH1 = ″;V1;″

CH2 = ″;V2

260 ′

270 X =X + .0025

280 IF X > 10 THEN X = 0

′INCREMENT X6 OUTPUT BY 2.5 MV

′RESET X6 RAMP

290 PRINT #1, USING ″X6, ##.###″;X ′SET X6 OUTPUT VOLTAGE

300 ′

310 GOTO 200

′LOOP FOREVER

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Program Example 2:

IBM PC, Microsoft Fortran

v3.3, via RS232

Machine language routines to interface to the

COM1: RS232 port are provided in the file

RS232.OBJ found on the SR575 disk. These

routines allow for simple interfacing to the SR530

at 19.2 kbaud from FORTRAN programs.

To use these routines, the file 'for232.inc' (also on

the SR575 disk) must be 'included' in the

FORTRAN source.

Only two wires between the IBM PC's ASYNC

port and the SR530 are needed (pins #2 & #3 of

the RS232), but pins 5,6,8 and 20 should be

connected together on the connector at the IBM

end.

$storage:2

$include: ′for232.inc′

[

for 232.inc must be included to call subroutines in RS232.OBJ

link with RS232.OBJ (on SR565 disk)

RS232.OBJ defines:

init

initializes COM1: to 19.2 kbaud

txstr (str) str is a string terminated with ′$′

transmits str to COM1:

rxstr (str) str must be declared with length of 15 or greater

fills str with string received from COM1:

if and error occurs, nocom is called.

Nocom should be a FORTRAN subroutine in your program.

program ex2

character *20 str1,str2, str3

[

Example program to read the SR530 outputs and ramp the

X6 analog output using Microsoft FORTRAN v3.3 and the

COM1: port. Set all switches in SW2 to UP on SR530

for 19.2 kbaud.

[

The ramp on X6 can be watched by setting the SR530

display to D/A/

[

initialize COM1: port to 19.2 kbaud

call init

set character wait interval to zero

call txstr(′w0$′)

[

reset X6 to zero

x6=0.0

[

read channel 1 output into string variable str1

call txstr(′q1$′)

call rxstr(str1)

read channel 2 output into string variable str2

[

call txstr(′q2$′)

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call rxstr(str2)

[

convert string variable into real variable v1 and v2

read (str1,1000) v1

read (str2,1000) v2

1000 format (bn,f10.0)

[

print results to screen

write(*,2000) v1, v2

2000 format(′ Channel 1=′,G10.3,3x, ′Channel 2=′,G10.3)

[

ramp x6 by 2.5 mV

x6 = x6 + .0025

if (x6.gt.10) x6 = 0.0

[

make x6 command string

write (str3,3000) x6

3000 format (′x6,′,f7.3,′$′)

call txstr(str3)

[

and loop forever

goto 20

stop

end

[

***********************************

subroutine nocom

[

in case of a timeout error, this routine runs

put your error handler here.

[

write(*,*) char (7)

write(*,*)′RS232 Timeout Error! ′

stop

end

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Program Example 3:

IBM PC, Microsoft C v3.0,

via RS232

Machine language routines to interface to the

COM1: RS232 port are provided in the file

RS232.OBJ found on the SR575 disk. These

routines allow for simple interfacing to the SR530

at 19.2 kbaud from C programs.

To use these routines, the large model must be

used. Compile with the /AL switch and link with

RS232.OBJ.

Only two wires between the IBM PC's ASYNC port

and the SR530 are needed (pins #2 & #3 of the

RS232), but pins 5,6,8 and 20 should be

connected together on the connector at the IBM

end.

#include <stdio.h>

Compile with >MSC program name/AL;

link with RS232.OBJ (on SR565 disk)

RS232.OBJ defines:

init ()

Initializes COM1: to 19.2 kbaud

txstr (str);

Char *str; str must terminate with ′$′ char

Sends string str to COM1:

str must be declared with 15 characters

or more length.

rxstr (str);

Fills str with string received from COM1:

If an error occurs, your procedure nocom() is called.

Nocom() must be a C procedure in your program.

Example program to read the SR510 outputs and ramp the x6 analog

Output using Microsoft C v3.0 (large model) and the COM1: port.

Set all switches in SW2 to UP on SR530 for 19.2 kbaud.

The ramp on x6 can be watched by setting the SR530 display to D/A.

main ()

{

char str1[20], str2[20], STR3[20];

float v1,V2,x;

init ();

txstr (″w0$″);

/* init COM1: port to 19.2 kbaud */

/* set character interval to 0 */

x = 0;

while (1)

{

txstr (″q1$″);

rxstr (str1);

/* read channel 1 output */

/* into str1 */

sscanf (str1, ″%f″, &v1); /* scan str1 for a float variable */

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txstr (″q2$″);

rxstr (str2);

/* read channel 2 output */

/* into str2 */

sscanf (str2, ″%f″, &v2); /* scan str2 for a float variable */

x += 0.0025;

/* increment x6 output by 2.5 mV */

if (x >= 10) x = 0;

sprintf (str3, ″X6,%f$″, x); /* make x6 command string */

txstr (str3);

/* send x6 command */

/* print results to screen */

printf (″Channel 1 = %10.36 Channel 2 = %10.36\n″, v1, v2);

}

/* ********************************************* */

nocom ()

/* error handling routine goes here */

{

printf(″RS232 Timeout Error\n″);

putch (7);

exit ();

}

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Program Example 4:

IBM PC,Microsoft Basic,

via GPIB

This program requires the Capital Equipment

Corporation GPIB card for the IBM PC or XT. It

has firmware in ROM to interface high level

languages to the GPIB.

In this program, the CEC card's ROM starts at

OC0000H, the system controller's address is 21,

and the SR530 has been assigned as GPIB

address 23.

Subroutine calls in Microsoft BASIC are done to

memory locations specified by the name of the

subroutine. The address is relative to the segment

address specified by the DEF SEG statement

preceding CALL.

To monitor the GPIB activity with an RS232

terminal, SW1-6 should be down, and the ASCII

terminal should be attached to the rear panel

RS232 connector.

10 ′ EXAMPLE PROGRAM TO READ THE SR530 OUTPUT AND RAMP THE X6 ANALOG OUTPUT

20 ′ USING IBM PC BASICA AND THE CAPITAL EQUIPMENT CORP. GPIB INTERFACE CARD

30 ′

40 ′ THE RAMP ON X6 CAN BE MATCHED BY SETTING THE SR530 DISPLAY TO D/A.

50 ′

60 ′ ON THE SR530 REAR PANEL, SET SWITCHES #4 AND #6 ON SW1 TO DOWN (DEVICE

70 ′ ADDRESS = 23, RS232 ECHO ON) AND SWITCH # 1 ON SW2 TO DOWN (RS232 BAUD

80 ′ RATE = 9600). ALL OTHER SWITCHES SHOULD BE UP.

90 ′ NOTE THAT THE RS232 ECHO IS FOR DEBUGGING AND DEMOSTRATION PURPOSES,

100 ′ UNDER NORMAL CONDITIONING, SWITCH # 6 OF SW1 SHOULD BE UP SINCE THE RS232

110 ′ ECHO SLOWS DOWN THE GPIB INTERFACE.

120 ′

130 DEF SEG = &HC000

140 INIT=0: TRANSMIT=3: RECV=6: ′ADDRESSES OF CEC FIRM WARE ROUTINES

150 ADDR%=21: SYS%=0 ′CONTROLLER ADDRESS

′BASE ADDRESS OF CEC CARD

160 INZ$ = ″IFC UNT UNL MTA LISTEN 23 DATA ′Z′ 13″

170 ′

180 Q1$ = ″IFC MTA LISTEN 23 DATA ′Q1′ 13″

190 Q2$ = ″IFC MTA LISTEN 23 DATA ′Q2′ 13″

200 X6$ = ″IFC MTA LISTEN 23 DATA ′X6, ″

210 LISN$ = ″IFC UNT UNL MLA TALK 23″

220 ′

230 ′

240 CALL INIT(ADDR%,SYS%)

′INIT X6 OUTPUT TO ZERO

250 CALL TRANSMIT(INZ$,STATUS%) ′RESET SR530

260 GOSUB 600

′CHECK TRANSMIT STATUS

270 ′

280 X = 0

′INIT X6 OUTPUT TO ZERO

290 ′

300 CALL TRANSMIT(Q1$,STATUS%)

310 GOSUB 600

′READ CHANNEL 1 OUTPUT

320 GOSUB 510

330 V1 = VAL(ANS$)

′GET RESULT

′INTO V1

340 ′

350 CALL TRANSMIT(Q2$,STATUS%)

360 GOSUB 600

′READ CHANNEL 2 OUTPUT

370 GOSUB 510

380 V1 = VAL(ANS$)

′GET RESULT

′INTO V2

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390 ′

400 PRINT “CH1 = ″;V1; ″

410 ′

CH2 =″;V2

420 X = X + .0025

430 IF X>10 THEN X 0

′INCREMENT X6 OUTPUT BY 2.5 MV

′RESET RAMP

440 X$ = X6$ + STR$(X) + ″′ 13″ ′MAKE X6 COMMAND STRING

450 CALL TRANSMIT (X$,STATUS%)

′SET NEW X6 VOLTAGE

460 GOSUB 600

470 ′

480 GOTO 300

′LOOP FOREVER

490 ′

500 ′ GET AN ANSWER STRING FROM THE SR530

510 CALL TRANSMIT(LISN$,STATUS%) ′MAKE SR530 A TALKER

520 GOSUB 600

530 ANS$=SPACE$(10)

′INIT ANSWER STRING

540 CALL RECV(ANS$,LENGTH%STATUS%) ′READ RESULT INTO ANS$

550 GOSUB 600

560 RETURN

570 ′

580 ′

590 ′ CHECK STATUS OF LAST TRANSMISSION FOR ERRORS

600 IF STATUS%=0 THEN RETURN

′STATUS OKAY

610 PRINT ″STATUS CODE = ″;STATUS%;″ ON GPIB: ERROR″

620 STOP

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Program Example 5:

HP85 via GPIB

This program provides an example of an HP85 program using the GPIB interface which could be used to

control the lockin amplifier. In this example, the SR530 should be addressed as device #16 by setting the

switch bank SW1 per the instructions Page 7.

x=0

OUTPUT 716 ; ″Q″

ENTER 716 : V1

DISP ″CH1 = ″ : V1

OUTPUT 716 ; ″Q2″

ENTER 716 : V2

DISP ″CH2 = ″ : V2

X = X + .0025

IF X>10 THEN X=0

100 OUTPUT 716 : ″X6, ″;X

110 GOTO 20

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Documentation

This section contains the parts lists and

schematics for the SR530 lock-in amplifier.

The first digit of any part number can be used to

locate the schematic diagram for the part. For

example, R415 is located on sheet 4 of the

schematic diagrams.

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SR530 COMPONENT PARTS LIST

Oscillator Board Parts List

REF.

C 1

C 2

C 3

C 4

C 5

C 6

C 7

C 8

SRS part#

VALUE

.1U

DESCRIPTION

5-00023-529

5-00102-517

5-00054-512

5-00087-516

5-00102-517

5-00014-501

5-00034-526

5-00100-517

5-00034-526

5-00100-517

4-00016-445

4-00003-440

4-00016-445

7-00037-701

4-00079-401

4-00083-401

4-00202-407

4-00189-407

4-00186-407

4-00190-407

4-00186-407

4-00202-407

4-00078-401

4-00186-407

4-00022-401

4-00042-401

4-00070-401

4-00034-401

4-00022-401

4-00079-401

4-00104-401

4-00034-401

4-00188-407

4-00022-401

4-00031-401

2-00013-215

3-00087-340

3-00085-340

3-00118-325

3-00124-325

0-00100-040

0-00122-053

0-00136-053

Cap, Monolythic Ceramic, 50V, 20%, Z5U

Capacitor, Tantalum, 35V, 20%, Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Silver Mica, 500V, 5%, DM15

Capacitor, Tantalum, 35V, 20%, Rad

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Electrolytic, 35V, 20%, Rad

Capacitor, Tantalum, 35V, 20%, Rad

Capacitor, Electrolytic, 35V, 20%, Rad

Capacitor, Tantalum, 35V, 20%, Rad

Pot, Multi-Turn, Side Adjust

4.7U

.047U

390P

4.7U

390P

100U

2.2U

100U

2.2U

10K

100K

10K

SR501

4.7K

47K

698

C 9

C 10

C 11

P 1

P 2

P 3

PC1

R 1

R 2

R 3

R 4

Trim Pot, Single Turn, In-Line Leads

Pot, Multi-Turn, Side Adjust

Printed Circuit Board

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Switch, Toggle Right Angle PCB Mount

Integrated Circuit (Thru-hole Pkg)

Transistor, TO-92 Package

41.2K

4.22K

42.2K

4.22K

698

R 5

R 6

R 7

R 8

R 9

39K

R 10

R 11

R 12

R 13

R 14

R 15

R 16

R 17

R 18

R 19

R 20

R 21

R 22

R 23

R 24

R 25

SW1

SW2

U 1

4.22K

1.0M

15K

30K

10K

1.0M

4.7K

82K

10K

4.99K

1.0M

100

DPDT

LF347

ICL8038

78L15

79L15

1/4X1/16

2-1/4" #24

8-1/2" #24

U 2

U 3

U 4

Z 0

Transistor, TO-92 Package

Washer, Flat

Wire #24 UL1007 Strip 1/4x1/4 Tin

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SR530 COMPONENT PARTS LIST

Main Board Parts List

REF.

BR1

BR2

BT1

SRS part#

VALUE

KBP201G/BR-81D

BR-2/3A 2PIN PC

.1U

10U

22P

100P

22P

2200U

10U

2.2U

47U

2.2U

47U

2.2U

1.0U

2200U

.22U

1.0U

.01U

10P

24P

DESCRIPTION

Integrated Circuit (Thru-hole Pkg)

Battery

3-00062-340

6-00001-612

5-00069-513

5-00038-509

5-00008-501

5-00002-501

5-00008-501

5-00030-520

5-00038-509

5-00081-516

5-00100-517

5-00035-521

5-00100-517

5-00035-521

5-00100-517

5-00060-512

5-00030-520

5-00057-512

5-00060-512

5-00052-512

5-00003-501

5-00009-501

5-00003-501

5-00017-501

5-00020-501

5-00109-525

5-00048-566

5-00051-512

5-00055-512

5-00060-512

5-00059-512

5-00003-501

5-00109-525

5-00048-566

5-00051-512

5-00055-512

5-00060-512

C 101

C 102

C 103

C 104

C 105

C 106

C 107

C 108

C 110

C 111

C 116

C 117

C 118

C 120

C 121

C 122

C 123

C 124

C 125

C 126

C 127

C 128

C 129

C 131

C 132

C 133

C 134

C 136

C 137

C 145

C 146

C 147

C 148

C 201

C 202

C 203

C 204

C 205

C 206

C 207

C 208

C 209

C 210

C 211

C 212

C 213

Capacitor, Mylar/Poly, 50V, 5%, Rad

Capacitor, Electrolytic, 50V, 20%, Rad

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Electrolytic, 16V, 20%, Rad

Capacitor, Electrolytic, 50V, 20%, Rad

Capacitor, Silver Mica, 500V, 5%, DM15

Capacitor, Tantalum, 35V, 20%, Rad

Capacitor, Electrolytic, 25V, 20%, Rad

Capacitor, Tantalum, 35V, 20%, Rad

Capacitor, Electrolytic, 25V, 20%, Rad

Capacitor, Tantalum, 35V, 20%, Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Electrolytic, 16V, 20%, Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Polystyrene, 50V, 5%, Ax

Cap, Polyester Film 50V 5% -40/+85c Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Polystyrene, 50V, 5%, Ax

Cap, Polyester Film 50V 5% -40/+85c Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

10P

47P

7.5P

150P

.0015U

.015U

.15U

1.0U

.47U

10P

150P

.0015U

.015U

.15U

1.0U

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

.47U

1.0U

.1U

10U

.15U

1.0U

10P

24P

560P

10U

1.0U

.001U

.33U

22P

47P

.1U

10U

1.0U

.001U

.33U

.001U

10P

47U

2.2U

47U

2.2U

470P

2.2U

1.0U

.01U

1.0U

.01U

10P

DESCRIPTION

C 214

C 215

C 216

C 217

C 218

C 230

C 301

C 302

C 303

C 304

C 305

C 306

C 307

C 308

C 310

C 311

C 312

C 313

C 314

C 315

C 317

C 318

C 319

C 320

C 321

C 322

C 323

C 324

C 325

C 326

C 327

C 328

C 329

C 330

C 331

C 332

C 333

C 334

C 335

C 336

C 337

C 338

C 401

C 402

C 403

C 404

C 405

C 406

C 407

C 408

C 409

5-00059-512

5-00060-512

5-00056-512

5-00038-509

5-00055-512

5-00060-512

5-00003-501

5-00009-501

5-00110-525

5-00038-509

5-00060-512

5-00049-566

5-00058-512

5-00008-501

5-00017-501

5-00056-512

5-00038-509

5-00060-512

5-00049-566

5-00058-512

5-00049-566

5-00003-501

5-00035-521

5-00100-517

5-00033-520

5-00100-517

5-00016-501

5-00100-517

5-00060-512

5-00052-512

5-00060-512

5-00052-512

5-00003-501

5-00056-512

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Electrolytic, 50V, 20%, Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Polystyrene, 50V, 5%, Ax

Capacitor, Electrolytic, 50V, 20%, Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Ceramic Disc, 50V, 10%, SL

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Electrolytic, 50V, 20%, Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Electrolytic, 25V, 20%, Rad

Capacitor, Tantalum, 35V, 20%, Rad

Capacitor, Electrolytic, 16V, 20%, Rad

Capacitor, Tantalum, 35V, 20%, Rad

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Tantalum, 35V, 20%, Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Ceramic Disc, 50V, 10%, SL

Cap, Stacked Metal Film 50V 5% -40/+85c

.1U

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

.1U

DESCRIPTION

C 410

C 411

C 412

C 413

C 414

C 415

C 416

C 417

C 418

C 419

C 420

C 421

C 422

C 501

C 502

C 503

C 504

C 505

C 506

C 507

C 508

C 509

C 510

C 511

C 512

C 513

C 514

C 515

C 516

C 517

C 518

C 519

C 520

C 521

C 523

C 525

C 526

C 527

C 701

C 702

C 703

C 704

C 705

C 706

C 707

C 708

C 709

C 710

C 711

C 712

C 801

5-00056-512

5-00049-566

5-00053-512

5-00072-513

5-00056-512

5-00060-512

5-00052-512

5-00049-566

5-00013-501

5-00012-501

5-00136-519

5-00007-501

5-00002-501

5-00008-501

5-00054-512

5-00049-566

5-00002-501

5-00056-512

5-00049-566

5-00052-512

5-00023-529

5-00007-501

5-00040-509

5-00052-512

5-00012-501

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Mylar/Poly, 50V, 5%, Rad

.1U

.001U

.033U

10U

.1U

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Polystyrene, 50V, 5%, Rad

Capacitor, Ceramic Disc, 50V, 10%, SL

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

Capacitor, Ceramic Disc, 50V, 10%, SL

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Monolythic Ceramic, 50V, 20%, Z5U

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Electrolytic, 50V, 20%, Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Ceramic Disc, 50V, 10%, SL

1.0U

.01U

.001U

33P

330P

.01U

220P

100P

22P

.047U

.001U

100P

.1U

.001U

.01U

.1U

220P

1.0U

.01U

330P

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

330P

.01U

2.2U

47U

2.2U

47U

22U MIN

2.2U

2200U

22U MIN

100U

1.0U

DESCRIPTION

C 802

C 803

C 804

C 805

C 806

C 807

C 808

C 809

C 901

C 902

C 903

C 904

C 905

C 906

C 907

C 908

C 909

C 910

C 911

C 912

C 913

C 914

C 915

C 916

C 917

C 918

C 919

C 920

C 923

C 924

C 925

C 926

C 927

C 928

C 929

C 930

C 931

C 932

C 933

C 934

C 935

C 936

C 937

C 938

C 939

CN801

CN802

CN803

CX1

5-00012-501

5-00052-512

5-00100-517

5-00035-521

5-00100-517

5-00035-521

5-00192-542

5-00100-517

5-00046-510

5-00192-542

5-00034-526

5-00103-524

5-00036-522

5-00056-512

5-00100-517

1-00014-160

1-00016-160

1-00238-161

5-00010-501

5-00014-501

Capacitor, Ceramic Disc, 50V, 10%, SL

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Tantalum, 35V, 20%, Rad

Capacitor, Electrolytic, 25V, 20%, Rad

Capacitor, Tantalum, 35V, 20%, Rad

Capacitor, Electrolytic, 25V, 20%, Rad

Cap, Mini Electrolytic, 50V, 20% Radial

Capacitor, Tantalum, 35V, 20%, Rad

Capacitor, Electrolytic, 50V, 20%, Ax

Cap, Mini Electrolytic, 50V, 20% Radial

Capacitor, Electrolytic, 35V, 20%, Rad

Capacitor, Tantalum, 50V, 20%, Rad

Cap, Electro. 25V 10% Ax, Mallory TCX

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Tantalum, 35V, 20%, Rad

Connector, D-Sub, Right Angle PC, Female

Connector, IEEE488, Reverse, R/A, Female

Capacitor, Ceramic Disc, 50V, 10%, SL

1.0U

6800U

.1U

2.2U

9 PIN D

RS232 25 PIN D

GPIB SHIELDED

270P

390P

CX713

CX714

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SR530 COMPONENT PARTS LIST

REF.

CY1

SRS part#

VALUE

4.000 MHZ

1N4148

1N747A

1N5711

1N4148

1N4007

1A 3AG

DESCRIPTION

Crystal

Diode

Fuse

Trim Pot, Single Turn, In-Line Leads

Pot, Multi-Turn Trim, 3/8" Square Top Ad

Trim Pot, Single Turn, In-Line Leads

Printed Circuit Board

Transistor, TO-71 Package

Transistor, TO-92 Package

Resistor, Carbon Comp, 1/4W, 5%

6-00010-620

3-00004-301

3-00007-301

3-00203-301

3-00004-301

3-00003-301

6-00004-611

4-00006-440

4-00012-441

4-00013-441

4-00014-441

4-00011-441

4-00002-440

7-00036-701

3-00016-323

3-00031-325

3-00887-325

3-00026-325

4-00033-404

D 101

D 102

D 103

D 104

D 105

D 106

D 201

D 202

D 203

D 204

D 301

D 302

D 303

D 401

D 402

D 403

D 404

D 501

D 502

D 701

D 702

D 703

D 704

D 901

D 902

D 903

D 904

FU1

P 101

P 102

P 103

P 104

P 105

P 401

P 402

P 403

P 404

P 501

P 502

PC1

20K

50K

10K

100

SR500

2N6485

MPSA18

MPS2907A

2N5210

100M

Q 101

Q 102

Q 103

Q 201

Q 202

Q 502

Q 701

Q 702

Q 703

R 101

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

100M

DESCRIPTION

Resistor, Carbon Comp, 1/4W, 5%

Resistor, Carbon Film, 1/4W, 5%

R 102

R 103

R 104

R 105

R 108

R 109

R 110

R 111

R 112

R 113

R 114

R 115

R 116

R 117

R 118

R 119

R 120

R 121

R 122

R 126

R 127

R 128

R 130

R 132

R 133

R 134

R 135

R 138

R 139

R 140

R 141

R 142

R 143

R 144

R 145

R 146

R 147

R 148

R 149

R 150

R 151

R 152

R 153

R 154

R 155

R 156

R 157

R 158

R 159

R 160

R 161

4-00033-404

4-00030-401

4-00031-401

4-00130-407

4-00199-407

4-00130-407

4-00145-407

4-00047-401

4-00196-407

4-00210-407

4-00130-407

4-00193-407

4-00180-407

4-00141-407

4-00210-407

4-00130-407

4-00021-401

4-00082-401

4-00179-407

4-00131-407

4-00052-401

4-00150-407

4-00174-407

4-00168-407

4-00150-407

4-00157-407

4-00193-407

4-00180-407

4-00141-407

4-00179-407

4-00201-407

4-00195-407

4-00176-407

4-00178-407

4-00211-407

4-00193-407

4-00180-407

4-00141-407

4-00033-404

4-00204-407

100

Resistor, Carbon Film, 1/4W, 5%

1.00K

6.81K

1.00K

110

2.2

6.04K

9.09K

1.00K

499

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

301

100

9.09K

1.00K

1.0K

470K

30.1K

1.00M

13.0K

280

22.6K

13.0K

16.9K

499

301

100

30.1K

634

54.9K

3.01K

3.83K

9.53K

499

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Comp, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

301

100

100M

750

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

4.99K

10M

DESCRIPTION

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

R 162

R 163

R 165

R 166

R 167

R 168

R 169

R 170

R 171

R 172

R 173

R 174

R 175

R 176

R 177

R 178

R 201

R 202

R 203

R 204

R 205

R 206

R 207

R 208

R 209

R 210

R 211

R 212

R 213

R 214

R 215

R 216

R 217

R 218

R 219

R 220

R 221

R 222

R 223

R 224

R 225

R 226

R 227

R 228

R 229

R 301

R 302

R 303

R 304

R 305

R 306

4-00188-407

4-00035-401

4-00215-407

4-00141-407

4-00215-407

4-00141-407

4-00134-407

4-00144-407

4-00182-407

4-00035-401

4-00193-407

4-00180-407

4-00165-407

4-00211-407

4-00130-407

4-00035-401

4-00135-407

4-00194-407

4-00138-407

4-00153-407

4-00138-407

4-00135-407

4-00130-407

4-00150-407

4-00033-404

4-00138-407

4-00135-407

4-00130-407

4-00150-407

4-00033-404

4-00032-401

4-00035-401

4-00032-401

4-00177-407

4-00039-401

4-00096-401

4-00039-401

4-00094-401

4-00063-401

4-00094-401

4-00063-401

4-00021-401

4-00034-401

4-00138-407

4-00045-401

4-00032-401

4-00021-401

909

100

909

100

1.24K

107

33.2

10M

499

301

200

9.53K

1.00K

10M

1.50K

5.11K

10.0K

15.0K

10.0K

1.50K

1.00K

13.0K

100M

10.0K

1.50K

1.00K

13.0K

100M

100K

10M

100K

3.48K

120K

62K

120K

6.8K

3.0K

6.8K

3.0K

1.0K

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Comp, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Comp, 1/4W, 5%

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

1.0K

10K

Resistor, Carbon Film, 1/4W, 5%

10.0K

2.0K

100K

1.0K

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

13K

DESCRIPTION

R 307

R 308

R 309

R 310

R 311

R 312

R 313

R 314

R 315

R 316

R 317

R 318

R 319

R 320

R 321

R 322

R 323

R 324

R 325

R 326

R 327

R 328

R 329

R 330

R 332

R 333

R 334

R 335

R 336

R 337

R 338

R 339

R 340

R 341

R 342

R 343

R 344

R 345

R 346

R 347

R 348

R 349

R 350

R 351

R 352

R 353

R 354

R 355

R 356

R 357

R 358

4-00040-401

4-00193-407

4-00073-401

4-00021-401

4-00034-401

4-00069-401

4-00099-401

4-00093-401

4-00138-407

4-00034-401

4-00032-401

4-00170-407

4-00199-407

4-00163-407

4-00150-407

4-00159-407

4-00029-401

4-00088-401

4-00021-401

4-00161-407

4-00029-401

4-00197-407

4-00088-401

4-00021-401

4-00035-401

4-00030-401

4-00032-401

4-00025-401

4-00073-401

4-00046-401

4-00069-401

4-00022-401

4-00021-401

4-00069-401

4-00093-401

4-00138-407

4-00032-401

4-00034-401

4-00203-407

4-00187-407

4-00160-407

4-00163-407

4-00034-401

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

499

330K

1.0K

10K

300K

680K

6.2K

10.0K

10K

100K

249K

6.81K

2.80K

13.0K

2.10K

1.8K

51K

1.0K

2.49K

1.8K

6.49K

51K

1.0K

10M

100K

1.2M

330K

2.0M

300K

1.0M

1.0K

300K

6.2K

10.0K

100K

10K

75.0K

4.53K

2.26K

2.80K

10K

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

2.0K

DESCRIPTION

Resistor, Carbon Film, 1/4W, 5%

R 359

R 360

R 361

R 362

R 363

R 364

R 365

R 366

R 367

R 368

R 369

R 370

R 371

R 372

R 373

R 374

R 375

R 376

R 377

R 378

R 401

R 402

R 403

R 404

R 405

R 406

R 407

R 408

R 409

R 410

R 411

R 412

R 413

R 414

R 415

R 417

R 418

R 419

R 420

R 421

R 422

R 423

R 424

R 425

R 426

R 427

R 428

R 429

R 430

R 431

R 432

4-00045-401

4-00032-401

4-00084-401

4-00181-407

4-00132-407

4-00032-401

4-00045-401

4-00021-401

4-00151-407

4-00156-407

4-00130-407

4-00030-401

4-00023-401

4-00033-404

4-00187-407

4-00045-401

4-00217-408

4-00085-401

4-00217-408

4-00193-407

4-00130-407

4-00131-407

4-00022-401

4-00217-408

4-00193-407

4-00217-408

4-00203-407

4-00080-401

4-00142-407

4-00034-401

4-00132-407

4-00179-407

4-00183-407

4-00155-407

4-00184-407

4-00212-407

4-00161-407

4-00021-401

4-00045-401

4-00131-407

4-00146-407

4-00140-407

4-00032-401

4-00021-401

100K

5.1K

32.4K

1.10K

100K

2.0K

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

1.0K

130K

16.2K

1.00K

1.1M

100M

4.53K

2.0K

1.000K

5.1M

1.000K

499

1.00K

1.00M

1.0M

1.000K

499

1.000K

75.0K

100K

10K

1.10K

30.1K

348K

150K

37.4K

9.76K

2.49K

1.0K

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Carbon Comp, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

2.0K

Resistor, Carbon Film, 1/4W, 5%

1.00M

110K

10.2K

100K

1.0K

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

1.0K

1.0M

10K

10.00K

20.00K

10.00K

20.00K

200K

806K

1.0K

10K

1.0K

10.00K

39K

DESCRIPTION

R 433

R 501

R 502

R 503

R 504

R 505

R 506

R 507

R 508

R 509

R 510

R 511

R 512

R 513

R 514

R 515

R 516

R 518

R 519

R 520

R 521

R 522

R 523

R 524

R 525

R 526

R 527

R 528

R 529

R 530

R 531

R 532

R 533

R 534

R 535

R 536

R 537

R 538

R 539

R 540

R 541

R 542

R 543

R 544

R 545

R 546

R 547

R 548

R 549

R 701

R 702

4-00021-401

4-00022-401

4-00034-401

4-00218-408

4-00219-408

4-00218-408

4-00219-408

4-00166-407

4-00207-407

4-00021-401

4-00034-401

4-00021-401

4-00086-401

4-00218-408

4-00078-401

4-00059-401

4-00032-401

4-00021-401

4-00034-401

4-00057-401

4-00210-407

4-00130-407

4-00032-401

4-00034-401

4-00057-401

4-00034-401

4-00057-401

4-00034-401

4-00057-401

4-00034-401

4-00057-401

4-00034-401

4-00042-401

4-00034-401

4-00042-401

4-00054-401

4-00032-401

4-00031-401

4-00079-401

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

22K

100K

1.0K

10K

220

9.09K

1.00K

100K

10K

220

10K

220

10K

220

10K

220

10K

15K

10K

15K

200K

100K

100

4.7K

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

1.5K

DESCRIPTION

R 703

R 705

R 706

R 707

R 708

R 709

R 710

R 711

R 712

R 801

R 802

R 803

R 901

R 902

R 903

R 904

R 905

R 906

R 907

R 908

R 909

R 910

R 911

R 912

R 913

R 914

RN401

RN801

RN802

SO702

SW1

4-00027-401

4-00021-401

4-00034-401

4-00069-401

4-00034-401

4-00032-401

4-00034-401

4-00032-401

4-00034-401

4-00065-401

4-00107-402

4-00060-401

4-00024-401

4-00060-401

4-00107-402

4-00053-401

4-00063-401

4-00053-401

4-00107-402

4-00220-420

4-00225-425

1-00026-150

2-00014-207

2-00017-216

2-00004-213

6-00007-610

8-00085-860

3-00076-340

3-00118-325

3-00124-325

3-00076-340

3-00130-340

3-00076-340

3-00088-340

3-00076-340

3-00089-340

3-00076-340

3-00089-340

3-00076-340

3-00089-340

3-00088-340

Resistor, Carbon Film, 1/4W, 5%

Resistor, Carbon Comp, 1/2W, 5%

Resistor, Carbon Film, 1/4W, 5%

Resistor, Carbon Comp, 1/2W, 5%

Resistor, Carbon Film, 1/4W, 5%

Resistor, Carbon Comp, 1/2W, 5%

Resistor Network, DIP, 1/4W,2%,8 Ind

Resistor Network SIP 1/4W 2% (Common)

Socket, THRU-HOLE

Switch, DIP

Switch, Rocker, PCB Mount (LHS of 510)

Switch, Rocker, PCB Mount (RHS of 510)

Transformer

SRS sub assemblies

Integrated Circuit (Thru-hole Pkg)

Transistor, TO-92 Package

Integrated Circuit (Thru-hole Pkg)

1.0K

10K

300K

10K

100K

10K

100K

10K

3.3K

240

1.2K

240

200

3.0K

200

10KX8

100KX9

28 PIN 600 MIL

SPSTX8

4PDT

DPDT

SR510/530

SR513 ASSY

DG211

78L15

79L15

DG211

5532A

DG211

LF353

DG211

LF357

DG211

LF357

DG211

LF357

LF353

SW2

SW601

SW602

T 1

U 101

U 102

U 103

U 104

U 105

U 106

U 107

U 108

U 109

U 110

U 111

U 112

U 113

U 114

U 115

U 117

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

5532A

DESCRIPTION

U 118

U 201

U 202

U 203

U 204

U 205

U 206

U 207

U 208

U 301

U 303

U 304

U 305

U 306

U 307

U 308

U 309

U 310

U 311

U 312

U 313

U 314

U 315

U 316

U 317

U 318

U 319

U 320

U 321

U 322

U 323

U 324

U 325

U 326

U 327

U 328

U 329

U 401

U 402

U 403

U 404

U 405

U 406

U 407

U 408

U 409

U 410

U 411

U 412

U 413

U 414

3-00130-340

3-00087-340

3-00093-340

3-00073-340

3-00076-340

3-00038-340

3-00087-340

3-00088-340

3-00076-340

3-00094-340

3-00075-340

3-00072-340

3-00093-340

3-00066-340

3-00093-340

3-00076-340

3-00049-340

3-00094-340

3-00072-340

3-00093-340

3-00076-340

3-00066-340

3-00076-340

3-00066-340

3-00093-340

3-00094-340

3-00091-340

3-00068-340

3-00076-340

3-00094-340

3-00076-340

3-00091-340

3-00090-340

3-00106-340

3-00074-340

3-00057-340

3-00090-340

3-00106-340

3-00090-340

3-00084-340

3-00126-335

Integrated Circuit (Thru-hole Pkg)

Relay

LF347

LM13600

CD4052

DG211

74HC139

LF347

LF353

DG211

LM311

CD4538

CD4046

LM13600

CA3140E

LM13600

DG211

74HC74

LM311

CD4046

LM13600

DG211

CA3140E

DG211

CA3140E

LM13600

LM311

LF412

CD4018

DG211

LM311

DG211

LF412

LF411

LT1007

CD4066

AD534

LF411

LT1007

LF411

ICL7650

51A05

Relay

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

DESCRIPTION

U 415

U 416

U 417

U 418

U 419

U 420

U 421

U 501

U 502

U 503

U 504

U 505

U 506

U 507

U 508

U 509

U 510

U 511

U 512

U 513

U 514

U 515

U 516

U 517

U 701

U 703

U 704

U 705

U 706

U 707

U 708

U 709

U 710

U 711

U 712

U 713

U 714

U 715

U 716

U 717

U 718

U 719

U 720

U 721

U 722

U 801

U 802

U 803

U 804

U 805

U 806

3-00126-335

3-00084-340

3-00126-335

3-00076-340

3-00090-340

3-00064-340

3-00035-340

3-00087-340

3-00058-340

3-00046-340

3-00077-340

3-00059-340

3-00058-340

3-00077-340

3-00087-340

3-00076-340

3-00087-340

3-00094-340

3-00087-340

3-00076-340

3-00092-340

3-00132-340

3-00081-341

3-00491-340

3-00037-340

3-00040-340

3-00049-340

3-00045-340

3-00051-340

3-00047-340

3-00049-340

3-00042-340

3-00044-340

3-00046-340

3-00039-340

3-00046-340

3-00045-340

3-00493-340

3-00111-340

3-00044-340

3-00049-340

3-00109-340

51A05

ICL7650

51A05

DG211

LF411

CA3081

74C74

LF347

AD7524

74HC374

DG528

AD7542JN

AD7524

DG528

LF347

DG211

LF347

LM311

LF347

Relay

Integrated Circuit (Thru-hole Pkg)

Relay

Integrated Circuit (Thru-hole Pkg)

STATIC RAM, I.C.

Integrated Circuit (Thru-hole Pkg)

DG211

LH0071

Z80A-CPU

2KX8-100

UPD71054C

74HC138

74HC157

74HC74

74HC32

74HCU04

74HC4040

74HC74

74HC175

74HC244

74HC374

74HC14

74HC374

74HC32

UPD71051C

MC68488

74HC244

74HC74

MC1488

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SR530 COMPONENT PARTS LIST

REF.

U 807

U 808

U 809

U 810

U 811

U 901

U 902

U 903

U 904

U 905

U 906

U 907

U 908

U 909

U 910

U 911

U 912

Z 0

SRS part#

VALUE

DESCRIPTION

3-00110-340

3-00078-340

3-00117-325

3-00123-325

3-00079-340

3-00095-331

3-00099-331

3-00114-329

3-00120-329

3-00113-340

3-00116-325

3-00096-340

3-00100-340

0-00005-007

0-00014-002

0-00016-000

0-00017-002

0-00019-003

0-00025-005

0-00043-011

0-00048-011

0-00064-027

0-00079-031

0-00084-032

0-00089-033

0-00095-040

0-00096-041

0-00113-053

0-00117-053

0-00119-053

0-00128-053

0-00130-050

0-00132-053

0-00136-053

0-00153-057

0-00185-021

0-00187-021

0-00207-003

0-00222-021

0-00225-052

0-00226-052

0-00227-052

0-00228-052

0-00231-043

0-00241-021

0-00249-021

0-00256-043

MC1489

DS75160A

78L12

79L12

DS75161A

LM317K

LM337K

7815

7915

7805CK

78L05

LM317L

LM337L

SR530

Integrated Circuit (Thru-hole Pkg)

Transistor, TO-92 Package

Integrated Circuit (Thru-hole Pkg)

Voltage Regulator, TO-3 Metal Can

Voltage Reg., TO-220 (TAB) Package

Integrated Circuit (Thru-hole Pkg)

Transistor, TO-92 Package

Integrated Circuit (Thru-hole Pkg)

Heat Sinks

Power_Entry Hardware

Hardware, Misc.

Power_Entry Hardware

Insulators

Lugs

Nut, Kep

Screw, Sheet Metal

Standoff

Termination

6J4

TIE ANCHOR

TRANSCOVER

MICA

3/8"

4-40 KEP

6-32 KEP

6-20X5/8P

4-40X3/16 M/F

36154

Tie

#4 FLAT

#4 SPLIT

10" #24

12" #24

15" #24

Washer, Flat

Washer, Split

Wire #24 UL1007 Strip 1/4x1/4 Tin

Wire #18 UL1007 Stripped 3/8x3/8 No Tin

Wire #24 UL1007 Strip 1/4x1/4 Tin

Grommet

Screw, Panhead Phillips

Insulators

Screw, Panhead Phillips

Wire #22 UL1007

Washer, nylon

Screw, Panhead Phillips

Washer, nylon

4" #24

5-5/8" #18

6-1/2" #24

8-1/2" #24

GROMMET2

6-32X3/8PP

4-40X1/4PP

TO-5

6-32X1/4PP

17" #22 BLACK

17" #22 WHITE

17" #22 RED

17" #22 GREEN

#4 SHOULDER

4-40X3/16PP

6-32X1-1/2PP

#6 SHOULDER

Z 0

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SR530 COMPONENT PARTS LIST

REF.

Z 0

SRS part#

VALUE

DESCRIPTION

Hardware, Misc.

0-00257-000

0-00371-026

0-00500-000

0-00521-048

0-00526-048

0-00893-026

1-00003-120

1-00010-130

1-00012-135

1-00013-135

1-00029-150

1-00053-172

7-00201-720

7-00202-720

7-00210-720

7-00212-720

7-00213-720

7-00214-720

9-00144-907

9-00188-917

9-00216-907

9-00217-907

HANDLE3

4-40X3/16PF

554808-1

3" #18

10-1/2" #18

8-32X3/8PF

BNC

20 PIN ELH

20 PIN CARD

40 PIN CARD

TO-3

Screw, Black, All Types

Hardware, Misc.

Wire, #18 UL1015 Strip 3/8 x 3/8 No Tin

Screw, Black, All Types

Connector, BNC

Connector, Male

Connector, Card Edge

Socket, THRU-HOLE

Line Cord

Fabricated Part

USA

SR500-32

SR500-33

SR530-22

SR530-26

SR530-27

SR530-28

3/32"BLACK

SR510/530 SER

1/8" BLACK

3/16" BLACK

Shrink Tubing

Product Labels

Shrink Tubing

Front Panel Board Parts List

REF.

C 607

SRS part#

VALUE

.1U

DESCRIPTION

5-00023-529

5-00019-501

5-00052-512

5-00023-529

3-00004-301

3-00012-306

Cap, Monolythic Ceramic, 50V, 20%, Z5U

Capacitor, Ceramic Disc, 50V, 10%, SL

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Monolythic Ceramic, 50V, 20%, Z5U

Diode

LED, Rectangular

C 608

C 609

C 610

C 6100

C 6101

C 6102

C 6103

C 6105

C 6106

D 601

.1U

68P

.01U

.1U

1N4148

GREEN

D 602

D 603

D 604

DS601

DS602

DS603

DS604

DS605

DS606

DS607

DS608

DS609

DS610

LED, Rectangular

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

GREEN

RED

DESCRIPTION

DS611

DS612

DS613

DS614

DS615

DS616

DS617

DS618

DS619

DS620

DS621

DS622

DS623

DS624

DS625

DS626

DS627

DS628

DS629

DS630

DS631

DS632

DS633

DS634

DS635

DS636

DS637

DS638

DS639

DS640

DS641

DS642

DS643

DS644

DS645

DS646

DS647

DS648

DS649

DS650

DS651

DS652

DS653

DS654

DS655

DS656

DS657

DS658

DS659

DS660

DS661

3-00012-306

3-00013-306

3-00012-306

LED, Rectangular

RED

GREEN

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

DESCRIPTION

DS662

DS663

DS664

DS665

DS666

DS667

DS668

DS669

DS670

DS671

LD1

3-00012-306

8-00001-820

8-00003-801

2-00001-201

7-00039-701

4-00034-401

4-00227-425

4-00226-425

GREEN

FE0206

-10/0/10S

D6-01-01

SR521

LED, Rectangular

LCD Display

Analog Meter

Switch, Momentary Push Button

Printed Circuit Board

LD2

LD3

M 1

M 2

PB601

PB602

PB603

PB604

PB605

PB606

PB607

PB608

PB609

PB610

PB611

PB612

PB613

PB614

PB615

PB616

PB617

PB618

PB619

PB620

PB621

PB622

PB623

PB624

PB625

PB626

PB627

PB628

PB629

PB630

PB631

PC1

R 601

R 602

RN601

RN602

10K

22KX9

150X9

Resistor, Carbon Film, 1/4W, 5%

Resistor Network SIP 1/4W 2% (Common)

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SR530 COMPONENT PARTS LIST

REF.

RN603

RN604

U 601

U 602

U 603

U 604

U 605

U 606

U 607

U 608

U 609

U 610

U 611

U 612

U 613

U 614

U 615

U 616

U 617

U 618

Z 0

SRS part#

VALUE

150X9

150X7

ICM7211AM

CD4030

74HC374

74HC175

74HC244

74LS164

4-40 HEX

3/16"X5/16"NYLN

#10 LOCK

#4 NYLON

CLEAR

1-3/4"#24B

1-3/4"#24R

12" #24

14" #24

15" #24

3-1/2" #24

4" #24

5" #24

8-1/2" #24

9" #26 X20

323914

20 PIN IDP

INSL

DESCRIPTION

4-00226-425

4-00222-425

3-00086-340

3-00071-340

3-00046-340

3-00042-340

3-00044-340

3-00053-340

0-00042-010

0-00077-030

0-00102-042

0-00104-043

0-00106-044

0-00111-053

0-00112-053

0-00117-053

0-00118-053

0-00119-053

0-00126-053

0-00128-053

0-00129-053

0-00136-053

0-00139-054

0-00203-032

1-00011-130

1-00073-120

1-00145-131

7-00305-710

7-00306-709

9-00815-924

Resistor Network SIP 1/4W 2% (Common)

Integrated Circuit (Thru-hole Pkg)

Nut, Hex

Spacer

Washer, lock

Washer, nylon

Window

Wire #24 UL1007 Strip 1/4x1/4 Tin

Wire #26 UL1061

Termination

Connector, Male

Connector, BNC

Connector, Female

Front Panel

Lexan Overlay

Tape, All types

Z 0

20 PIN DIF POL

SR530-31

SR530-32-36

DBL-SIDED 1/2"

Z 0

Quad Board Parts List

REF.

SRS part#

VALUE

470P

10U

1.0U

.001U

DESCRIPTION

C 1001

C 1002

C 1004

C 1005

5-00016-501

5-00038-509

5-00060-512

5-00049-566

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Electrolytic, 50V, 20%, Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

.33U

.001U

10P

47U

DESCRIPTION

C 1006

C 1007

C 1008

C 1009

C 1010

C 1011

C 1012

C 1013

C 1014

C 1015

C 1016

C 1017

C 1018

C 1101

C 1102

C 1103

C 1104

C 1105

C 1106

C 1107

C 1108

C 1109

C 1110

C 1111

C 1112

C 1113

C 1114

C 1115

C 1116

C 1117

C 1120

C 1121

C 1122

C 1123

C 1124

C 1125

C 1126

C 1201

C 1202

C 1203

C 1204

C 1205

C 1206

C 1207

C 1208

D 1001

D 1002

D 1103

D 1104

P 1101

P 1102

5-00058-512

5-00049-566

5-00003-501

5-00035-521

5-00100-517

5-00008-501

5-00060-512

5-00023-529

5-00060-512

5-00023-529

5-00003-501

5-00056-512

5-00049-566

5-00053-512

5-00072-513

5-00056-512

5-00060-512

5-00049-566

5-00013-501

5-00054-512

5-00023-529

5-00012-501

5-00136-519

5-00049-566

5-00023-529

3-00004-301

4-00016-445

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Electrolytic, 25V, 20%, Rad

Capacitor, Tantalum, 35V, 20%, Rad

Capacitor, Ceramic Disc, 50V, 10%, SL

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Monolythic Ceramic, 50V, 20%, Z5U

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Monolythic Ceramic, 50V, 20%, Z5U

Capacitor, Ceramic Disc, 50V, 10%, SL

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Capacitor, Mylar/Poly, 50V, 5%, Rad

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Polyester Film 50V 5% -40/+85c Rad

Capacitor, Ceramic Disc, 50V, 10%, SL

Cap, Stacked Metal Film 50V 5% -40/+85c

Cap, Monolythic Ceramic, 50V, 20%, Z5U

Capacitor, Ceramic Disc, 50V, 10%, SL

Capacitor, Polystyrene, 50V, 5%, Rad

Cap, Polyester Film 50V 5% -40/+85c Rad

Cap, Monolythic Ceramic, 50V, 20%, Z5U

Diode

47U

2.2U

22P

1.0U

.1U

1.0U

.1U

10P

.1U

.001U

.033U

10U

.1U

1.0U

.001U

33P

.047U

.1U

330P

.01U

.001U

.1U

1N4148

10K

Diode

Pot, Multi-Turn, Side Adjust

10K

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

10K

SR522

2N5210

2.0K

1.0K

DESCRIPTION

Pot, Multi-Turn, Side Adjust

Printed Circuit Board

Transistor, TO-92 Package

P 1103

P 1104

P 1201

P 1202

PC1

4-00016-445

7-00040-701

3-00026-325

4-00045-401

4-00021-401

4-00069-401

4-00093-401

4-00022-401

4-00069-401

4-00046-401

4-00073-401

4-00032-401

4-00138-407

4-00203-407

4-00032-401

4-00034-401

4-00187-407

4-00160-407

4-00163-407

4-00084-401

4-00032-401

4-00181-407

4-00132-407

4-00151-407

4-00156-407

4-00130-407

4-00034-401

4-00032-401

4-00045-401

4-00088-401

4-00030-401

4-00033-404

4-00187-407

4-00045-401

4-00217-408

4-00085-401

4-00217-408

4-00193-407

4-00130-407

4-00131-407

Q 1201

R 1001

R 1002

R 1003

R 1004

R 1005

R 1006

R 1007

R 1008

R 1009

R 1010

R 1011

R 1012

R 1013

R 1014

R 1015

R 1016

R 1017

R 1018

R 1019

R 1020

R 1021

R 1022

R 1023

R 1024

R 1025

R 1026

R 1027

R 1028

R 1029

R 1030

R 1031

R 1032

R 1033

R 1034

R 1035

R 1036

R 1037

R 1101

R 1102

R 1103

R 1104

R 1105

R 1106

R 1107

R 1108

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Carbon Comp, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Metal Film, 1/8W, 1%, 50PPM

1.0K

300K

6.2K

1.0M

300K

2.0M

330K

100K

10.0K

75.0K

100K

10K

4.53K

2.26K

2.80K

5.1K

100K

32.4K

1.10K

130K

16.2K

1.00K

10K

100K

2.0K

51K

100M

4.53K

2.0K

1.000K

5.1M

1.000K

499

1.00K

1.00M

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

1.0M

DESCRIPTION

R 1109

R 1110

R 1111

R 1112

R 1113

R 1114

R 1115

R 1116

R 1117

R 1118

R 1119

R 1120

R 1121

R 1122

R 1123

R 1124

R 1125

R 1126

R 1127

R 1128

R 1129

R 1130

R 1132

R 1133

R 1201

R 1202

R 1203

R 1204

R 1205

R 1206

R 1207

R 1208

R 1209

R 1210

R 1211

R 1212

U 1001

U 1002

U 1003

U 1004

U 1005

U 1006

U 1007

U 1008

U 1009

U 1010

U 1011

U 1012

U 1013

U 1014

U 1101

4-00022-401

4-00217-408

4-00193-407

4-00217-408

4-00203-407

4-00080-401

4-00142-407

4-00032-401

4-00034-401

4-00132-407

4-00179-407

4-00183-407

4-00155-407

4-00184-407

4-00212-407

4-00161-407

4-00021-401

4-00045-401

4-00131-407

4-00146-407

4-00140-407

4-00021-401

4-00218-408

4-00219-408

4-00218-408

4-00219-408

4-00210-407

4-00130-407

4-00032-401

4-00034-401

4-00057-401

4-00034-401

4-00057-401

3-00094-340

3-00072-340

3-00076-340

3-00094-340

3-00093-340

3-00066-340

3-00076-340

3-00066-340

3-00093-340

3-00076-340

3-00094-340

3-00068-340

3-00091-340

3-00076-340

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Resistor, Metal Film, 1/8W, 0.1%, 25ppm

Resistor, Metal Film, 1/8W, 1%, 50PPM

Resistor, Carbon Film, 1/4W, 5%

Integrated Circuit (Thru-hole Pkg)

1.000K

499

1.000K

75.0K

100K

10K

1.10K

30.1K

348K

150K

37.4K

9.76K

2.49K

1.0K

2.0K

1.00M

110K

10.2K

1.0K

10.00K

20.00K

10.00K

20.00K

9.09K

1.00K

100K

10K

220

10K

220

LM311

CD4046

DG211

LM311

LM13600

CA3140E

DG211

CA3140E

LM13600

DG211

LM311

CD4018

LF412

DG211

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SR530 COMPONENT PARTS LIST

REF.

SRS part#

VALUE

LF412

LF411

LT1007

CD4066

AD534

LF411

LT1007

LF411

ICL7650

51A05

ICL7650

51A05

DG211

LF411

LF353

74C74

AD7524

LF347

DG211

LF411

DESCRIPTION

U 1102

U 1103

U 1104

U 1105

U 1106

U 1107

U 1108

U 1109

U 1110

U 1111

U 1112

U 1113

U 1114

U 1115

U 1116

U 1117

U 1118

U 1119

U 1120

U 1121

U 1201

U 1202

U 1203

U 1204

U 1205

3-00091-340

3-00090-340

3-00106-340

3-00074-340

3-00057-340

3-00090-340

3-00106-340

3-00090-340

3-00084-340

3-00126-335

3-00084-340

3-00126-335

3-00076-340

3-00090-340

3-00088-340

3-00035-340

3-00058-340

3-00087-340

3-00076-340

3-00090-340

Integrated Circuit (Thru-hole Pkg)

Relay

Integrated Circuit (Thru-hole Pkg)

Relay

Integrated Circuit (Thru-hole Pkg)

Miscellaneous Parts List

REF.

U 702

Z 0

SRS part#

VALUE

27128-150

4-40 MINI

DESCRIPTION

EPROM/PROM, I.C.

Nut, Mini

3-00161-342

0-00045-013

0-00078-031

0-00167-023

0-00179-000

0-00180-000

0-00185-021

0-00187-021

0-00204-000

0-00209-021

0-00247-026

0-00248-026

0-00371-026

6-00054-611

7-00147-720

7-00203-720

7-00204-720

7-00211-720

7-00215-720

7-00216-720

4-40X1 M/F

6-32X1/2RP

RIGHT FOOT

LEFT FOOT

6-32X3/8PP

4-40X1/4PP

REAR FOOT

4-40X3/8PP

6-32X1/4 TRUSSP

10-32X3/8TRUSSP

4-40X3/16PF

.375A 3AG

BAIL

Standoff

Screw, Roundhead Phillips

Hardware, Misc.

Screw, Panhead Phillips

Hardware, Misc.

Screw, Panhead Phillips

Screw, Black, All Types

Fuse

Fabricated Part

SR500-34

SR500-35

SR530-25

SR530-29

SR530-30

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