HP (Hewlett Packard) Hewlett Packard Car Amplifier 8808A User Manual

TM 11-6625-2872-14&P

TECHNICAL MANUAL

OPERATOR'S, ORGANIZATIONAL,

DIRECT SUPPORT AND GENERAL SUPPORT

MAINTENANCE MANUAL

(INCLUDING REPAIR PARTS AND SPECIAL TOOLS LIST)

FOR

PREAMPLIFIER, LOGARITHMIC

AM-6681(V)1/U

(HEWLETT-PACKARD MODEL 8808A)

(NSN 6625-00-134-3557)

HEADQUARTERS, DEPARTMENT OF THE ARMY

12 MARCH 1981

This manual contains copyright material reproduced by permission of the Hewlett-Packard Company.

TM 11-6625-2872-14&P

TEHNICAL MANUAL

HEADQUARTERS

DEPARTMENT OF THE ARMY

WASHINGTON, DC, 12 March 1981

}

No. 11-6625-2872-14&P

OPERATOR'S, ORGANIZATIONAL, DIRECT SUPPORT,

AND GENERAL SUPPORT MAINTENANCE MANUAL

(INCLUDING REPAIR PARTS AND SPECIAL TOOLS LIST)

FOR

PREAMPLIFIER, LOGARITHMIC AM-6681(V)l/U

(HEWLETT-PACKARD MODEL 8808A)

(NSN 6625-00-134-3557)

REPORTING ERRORS AND RECOMMENDING IMPROVEMENTS

You can help Improve this manual. If you find any mistakes or if you know of a way to

improve the procedures, please let us know. Mail your letter, DA Form 2028

(Recommended Changes to Publications and Blank Forms), or DA Form 2028-2 located in

back of this manual direct to Commander, US Army Communications and Electronics

Materiel Readiness Command, ATTN: DRSEL-ME-MQ, Fort Monmouth, NJ 07703. In either

case, a reply will be furnished direct to you.

This manual is an authentication of the manufacturer's commercial literature which, through usage, has been

found to cover the data required to operate and maintain this equipment. Since the manual was not prepared in

accordance with military specifications, the format has not been structured to consider levels of maintenance.

TM 11-6625-2872-14&P

TABLE OF CONTENTS

Paragraph

Page

SECTION

INTRODUCTION

Scope......................................................................................................

Indexes of Publications . . . . ...............................................................

Maintenance Forms, Records, and

0-1

0-2

0-1

Reports .............................................................................................

Reporting Equipment Improvement

0-3

0-1

Recommendations (EIR)..........................................................................

Administrative Storage ............................................................................

Destruction of Army Electronics

0-4

0-5

0-1

Materiel.............................................................................................

0-6

1-1

0-1

GENERAL INFORMATION

Description ..............................................................................................

II.

INSTALLATION

Portable Case or Rack Mounting .............................................................

Installation in Sanborn Recording

2-1

2-5

Systems ............................................................................................

III.

OPERATION

Operating Controls...................................................................................

Balancing ................................................................................................

Calibration...............................................................................................

Alternate Calibration Procedure...............................................................

Operation ................................................................................................

50 dB Span Operation .............................................................................

100 dB Span Operation ...........................................................................

Operation with Monitoring Instruments.....................................................

Simultaneous Recording and Monitoring

of 8808A Output................................................................................

3-27

IV.

PRINCIPLES OF OPERATION

Output .....................................................................................................

Stage Description ....................................................................................

Signal Flow..............................................................................................

Dynamic Range.......................................................................................

Block Diagram Information ......................................................................

Detector Outputs .....................................................................................

DB SPAN Switch Circuit ..........................................................................

LOG ZERO Level Setting ........................................................................

REPLACEABLE PARTS

Introduction..............................................................................................

Ordering Information................................................................................

5-1

5-3

TM 11-6625-2872-14&P

TABLE OF CONTENTS - Continued

Page

APPENDIX

REFERENCES....................................................................................................

A-1

COMPONENTS OF END ITEM LIST (COEIL)

(Not applicable)

BASIC ISSUE ITEMS LIST (BIIL)

(Not applicable)

MAINTENANCE ALLOCATION

Section

Introduction..........................................................................................................

Maintenance Allocation Chart for Plug-In

Amplifier AM-6681(V)1/U ..............................................................................

III.

Tool and Test Equipment Requirements for

Plug-In Amplifier AM-6681(V)1/U ..................................................................

iii

TM 11-6625-2872-14&P

LIST OF ILLUSTRATIONS

Number

1-1

Page

8808A Log Level Preamplifier ....................................................................................................

8808A Successive Detector ......................................................................................................

8808A Block Diagram ................................................................................................................

4-1

4-2

FO 5-1

Model 8808A Log Level Schematic ............................................................................................ In back

of manual

LIST OF TABLES

Number

1-1

Page

Specifications ............................................................................................................................

Bottom and Full Scale Signal Levels..........................................................................................

Reference Designation Index .....................................................................................................

3-1

5-1

5-2

Part Number - National Stock Number

Cross Reference Index ........................................................................................................

TM 11-6625-2872-14&P

SECTION 0

INTRODUCTION

0-1. SCOPE.

This manual describes Logarithmic Preamplifier AM-6681(V)1/U and provides instructions for operation and

maintenance. Throughout this manual, the preamplifier is referred to as Hewlett-Packard Model 8808A Log-Audio

Preamplifier.

0-2. INDEXES OF PUBLICATIONS.

a. DA Pam 310-4. Refer to the latest issue of DA Pam 310-4 to determine whether there are new editions,

changes, or additional publications pertaining to the equipment.

b. DA Pam 310-7. Refer to DA Pam 310-7 to determine whether there are modification work orders (MWO's)

pertaining to the equipment.

0-3. MAINTENANCE FORMS, RECORDS, AND REPORTS.

a. Reports of Maintenance and Unsatisfactory Equipment. Department of the Army forms and procedures used for

equipment maintenance will be those prescribed by TM 38-750, The Army Maintenance Management System.

b. Report of Item and Packaging Discrepancies. Fill out and forward SF 364 (Report of Discrepancy (ROD)) as

prescribed in AR 735-11-2/DLAR 4140.55/NAVMATINST 4355.73/AFR 400-54/MCO 4430.3E.

c. Discrepancy in Shipment Report (DISREP) (SF 361). Fill out and forward Discrepancy in Shipment Report

(DISREP) (SF 361) as prescribed in AR 55-38/NAVSUPINST 4610.33B/AFR 75-18/MCO P4610.19C and DLAR 4500.15.

0-4. REPORTING EQUIPMENT IMPROVEMENT RECOMMENDATIONS (EIR).

If your equipment needs improvement, let us know. Send us an EIR. You, the user, are the only one who can tell

us what you don't like about your equipment. Let us know why you don't like the design. Tell us why a procedure is hard

to perform. Put it on an SF 368 (Quality Deficiency Report). Mail it to Commander, US Army Communications and

Electronics Materiel Readiness Command, ATTN: DRSEL-ME-MQ, Fort Monmouth, New Jersey 07703. We'll send you

a reply.

0-5. ADMINISTRATIVE STORAGE.

Administrative storage of equipment issued to and used by Army activities shall be in accordance with TM 740-90-1.

0-6. DESTRUCTION OF ARMY ELECTRONICS MATERIEL.

Destruction of Army electronics materiel to prevent enemy use shall be in accordance with TM 750-244-2.

0-1/(0-2 Blank)

TM-11-6625-2872-14&P

SECTION I

GENERAL INFORMATION

1-1. DESCRIPTION.

1-2 The 8808A is a Log Level Preamplifier which

produces a dc output proportional to the logarithm of

the ac input signal, over an extremely wide range of

signal amplitudes. The input signal dynamic range

can be up to 100 dB (100,000:1). In addition, a

50 dB (320:1) span is provided for greater signal resolution

1-3. The Preamplifier is designed for use with low

output impedance accelerometers, as well as vibration

and acoustic transducers, which have outputs in the

frequency range of 5 Hz to 100 kHz. It is also useful

for continuous monitoring or recording of signal output

in dB during frequency analysis of amplifiers, filters,

transmission networks, and similar devices.

1-4. The 8808A can be plugged into Sanborn direct

writing recording systems. When used with recorders

having 50 division chart paper, the calibrated output is

2 dB per division for the 100 dB span, or 1 dB per

division for the 50 dB span. Also, the preamplifier

can be benchtop or rack mounted, with the output

connected to a monitoring instrument such as a

voltmeter or oscilloscope. For recording, a strip

chart recorder or magnetic tape recorder can be

connected to the output.

1-5. The range switch provides nine bottom scale

sensitivities in 10 dB steps from 0 dBV to -80 dBV

(dBV = decibels referred to 1 volt RMS). For the

50 dB span, the full scale signal is 50 dB above the

bottom scale level. For the 100 dB span, the full scale

signal is 100 dB above the bottom scale level.

1-6. All nine RANGE switch positions can be used with

the 50 dB span. The four switch positions outlined in

red on the panel (-50, -60, -70, -80) are used for the 100

dB span only.

1-7. Specifications for the 8808A Log Level Preamplifier are

given in Table 1-1.

Figure 1-1. 8808A Log Level Preamplifier

-1-

TM 11-6625-2872-14&P

Table 1-1. Specifications

ELECTRICAL SPECIFICATIONS

INPUT RESISTANCE: Single-ended to ground 1 megohm minimum.

SIGNAL DETECTION: Full-wave average. 50 dB or 100 dB span, switch selected from front panel.

DETECTION ACCURACY: ± 1 dB maximum error, sine wave input.

MAXIMUM SENSITIVITY: 100 mV rms of sine wave corresponds to bottom scale on most sensitive range.

GAIN STABILITY: Temperature: Less than 2 dB/10°C, 0° to 40°C. Line Voltage: Less than 0.5 dB, 103 to 127 volts.

ATTENUATION: 50 dB span ranges: 9 bottom scale ranges at -80 dBV to 0 dBV in 10 dB steps corresponding to

100 mV, 320 mV, 1 mV, 3.2 mV, 10 mV, 32 mV, 100 mV, 320 mV and 1 volt. Top scale is nominally 50 dB (320X) above

bottom scale.

100 dB span ranges: 4 bottom scale ranges at -80 dBV to -50 dBV in 10 dB steps corresponding to 100 mV, 320 mV, 1 mV

and 3.2 mV. Top scale is normally 100 dB (100,000X) above bottom scale.

ATTENUATION ACCURACY: ± 3% maximum error (0.25 dB) for -80 to -50 dBV attenuation ranges. For other ranges,

detection error (± 1 dB) may add to attenuation error.

OUTPUT: Single-ended to ground, ± 2..5 V maximum or 0 to +5 volts across 1000 ohms minimum.

OUTPUT RESISTANCE: Approximately 10 ohms.

SIGNAL BANDWIDTH: 5 Hz to 100 kHz, less than 3 dB down from mid-band level on SLOW response range. 500 Hz to

100 kHz on FAST response range.

SIGNAL CREST FACTOR: 3 to 1 at full scale on 100 dB span, ±500 volts peak maximum allowed.

DETECTION RESPONSE TIME: For a step change in input amplitude with ratio of 40 dB (100:1) or greater, the time

required for the output to increase or decrease between values corresponding to 105 and 90% of the maximum applied

signal (i.e. , 20 dB below max. applied signal and 1 dB below max applied signal) is approximately 20 msec in FAST

position and 2 sec in SLOW position. i. e. , average rate of change of output under these conditions corresponds to

approximately 900 dB/ sec in FAST: 9 dB/sec in SLOW.

OUTPUT NOISE: Maximum noise appears at bottom scale. 50 dB span: 80 mV pp: 100 dB span: 40 mV pp.

INTERNAL CALIBRATION: -80 and +20 dBV, internally adjustable; -30 dBV accurate to + 0.5 dB. Stability: less than

0.25 dB, 10° to 40°C or 103 to 127 volts; approximately 500 Hz.

GENERAL SPECIFICATIONS

Terminals: DC output on front panel. Input and auxiliary DC output on rear of mating power supply.

Front Panel Controls: RANGE switch; GAIN potentiometer locking; LOG ZERO, 10-turn potentiometer, locking; 50/100

dB SPAN switch; SPAN BALANCE, screwdriver adjust; RESPONSE TIME/CAL switch.

Internal Controls: Signal Board: Balance adjust; CAL adjust (2); Zero Suppression adjust; Attenuator compensation

trimmers (4). Detector Board: 100 dB span mid-scale adjust.

Weight: Approximately 5 lb. (2, 3 kg).

Front Panel Dimensions: 7" high, 2-1/16" wide (178 x 52 mm).

Note: When Preamplifier is used in a recording system, these specifications are affected by performance of the recorder

and driver amplifiers. (Consult data sheet of appropriate system for details.)

All Sanborn 8800 Series Amplifiers are tested for performance under normal production environmental conditions:

ambient temperature 20° to 30° C and relative humidity less than 80% unless otherwise noted.

-2-

TM 11-625-2872-14&P

SECTION II INSTALLATION

2-1. PORTABLE CASE OR RACK MOUNTING.

2-2. The 8808A is operated as a self-contained instrument using an 860-500 Power Supply to furnish operating power for

the preamplifier. The preamplifier power supply combination operates on a 115/230 volt 50 or 60 Hz power line. See the

power supply Operating and Service Manual, IM-860-500-3.

2-3. The preamplifier power supply combination can be mounted in the 860-1400 Case for single channel benchtop

operation. For two channel operation, two preamplifiers and power supplies mount in an 860-200 Module, for benchtop

or rack mounting.

2-4. When the 8808A is operated with the 860-500 Power Supply, preamplifier input and output signal connections are

made on the rear panel of the power supply as follows:

Signal Input Jack J3:

Plus (+) signal pin A

Signal ground pin B

Mating connector is 10G3-34FW

Plus (+) signal pin A

Signal Output Jack J2:

Signal ground pin E

Mating connector is 10B9-5MW

For monitoring, connect the preamplifier output signal to a voltmeter, oscilloscope, or other voltage indicating instrument

which has a signal range of 0 to +5 volts or 2.5 volts. The output signal can be recorded using a strip chart recorder,

magnetic tape recorder, or other instrument which will operate with an input of 0 to +5 volts, or ± 2. 5 volts.

2-5. INSTALLATION IN SANBORN RECORDING SYSTEMS.

2-6. The 8808A can be installed in Sanborn Recording Systems 7701A, 7702A, 7704A, 7706A, 7708A, for 1, 2, 4, 6, or 8

channels of recording using the heated stylus recording technique. Operating power for the preamplifier is supplied by

the recording system. See the recording system instruction manual for installation information.

2-7. The 7701A Recorder is supplied in a portable case. The 7702A Recorder is supplied either in a mobile cart, or for

rack mounting. The 7706A, 7708A Recorders are rack mounted.

SECTION III OPERATION

3-1. OPERATING CONTROLS.

3-2. RANGE switch selects the bottom scale

signal level. Scale is calibrated in dBV

(decibels referred to a 1 volt rrns signal). Full

scale signal for 50 Db span operation is 50 dB

above bottom scale signal. For 100 dB span,

full scale signal is 100 dB above bottom scale

signal. Bottom scale and corresponding full

scale signal levels for each setting of the

RANGE switch are given in Table 3-1.

50 DB SPAN

Range

Switch

Setting

Bottom Scale

Volts rms

Full Scale

Volts rms

dBV

-10

-20

-30

-40

-50

-60

-70

-80

1 V

.316V

.100V

31.6 mnV

10 mV

3.16 mV

1 mV

316 mV

100 mV

+50

+40

+30

+20

+10

316 V

100 V

31.6 V

10 V

3.16 V

1 V

-10

-20

-30

-40

-50

-60

-70

-80

3-3. DB SPAN switch selects either 50 dB or

100 dB maximum span between the bottom

scale and full scale input signal levels.

-10

-20

-30

.316 V

.1 V

31.6 mV

NOTE

On the 100 dB span, only the -

50, -60, -70, -80 RANGE switch

positions are used.

100 DB SPAN

-50

-60

-70

-80

-50

-60

-70

-80

3.16 mV

1 mV

316 mV

100 mV

+50

+40

+30

+20

316 V

100 V

31.6 V

10 V

Switch also indicates recorder calibration: 1

dB/div for 50 dB span. 2 dB/div for 100 dB

span.

Table 3-1. Bottom and Full Scale Signal Levels

-3-

TM 11-6625-2872-14&P

3-4. GAIN control sets the preamplifier output level for a full scale cal signal applied to the preamplifier input. For use in

recording systems, full scale output corresponds to the top division on the recorder chart ( approx. -2.5 volts preamp

output). For use with a voltmeter or oscilloscope, full scale output is +5 volts.

3-5. LOG ZERO control sets the preamplifier output level for a bottom scale cal signal applied to the preamplifier input.

For use in recording systems, bottom scale output-corresponds to the bottom division on the recording chart (approx. -2.5

volts preamp output). For use with a voltmeter or oscilloscope, bottom scale output is 0 volts.

3-6. SPAN BALANCE control balances the preamplifier, to obtain the same output on the 100 and 50 dB spans for a -80

dBV calibration signal level.

3-7. RESP TIME,/CAL DB switch selects the operating mode. FAST and SLOW response times are the use positions.

OFF position disconnects the input signal from the preamplifier, and grounds the preamplifier input. -80, -30, +20 dB

CAL positions select calibration voltage levels supplied by a 500 Hz oscillator in the preamp.

3-8. OUTPUT jack provides the preamplifier output signal at the front panel, for monitoring purposes. Mates with 10G2-

22MW plug.

3-9. BALANCING

3-10. Allow preamplifier to warm up several minutes before balancing.

a. Set the RESP TIME/CAL DB and RANGE switches to the -80 position.

b. Adjust the LOG ZERO control for approximately bottom scale output.

c. Alternately set the DB SPAN switch to the 50 and 100 positions while adjusting the SPAN BALANCE control for

minimum change in the preamp output.

NOTE

Approximately ± 20 mnV noise normally present at the preamplifier output will cause a slight

fluctuation in the reading observed on a voltmeter or oscilloscope connected to the output.

3-11. CALIBRATION

a. Set the DB SPAN switch to 100.

b. Set the RANGE switch to 80.

c. Set the RESP TIME/CAL DB switch to -80.

d. Adjust the LOG ZERO control for bottom scale output.

e. Set the RESP TIME/CAL DB switch to +20 and adjust the GAIN control for full scale output.

f. Repeat steps 3-11 (c) through 3-11 (e) to eliminate the effects of control interaction.

g. Set the RESP TIME/CAL DB switch to OFF. With the switch OFF, a negative voltage is normally present at the

preamp output, which will position the recorder stylus offscale.

NOTE

Preamp RANGE switch must be in the -80 position during the calibration procedure.

3-12. ALTERNATE CALIBRATION PROCEDURE.

3-13. To calibrate the preamplifier with the DB SPAN switch in the 50 dB position, use the below procedure:

a. Set the DB SPAN switch to 50.

b. Set the RANGE switch to -80.

c. Set the RESP TIME/CAL DB switch to -80.

d. Adjust the LOG ZERO control for bottom scale output.

e. Set the RESP TIME/CAL DB switch to -30 and adjust the GAIN control for full scale output.

f. Repeat steps 3-13 (c, d, e) to eliminate the effects of control interaction.

g. Set the RESP TIME/CAL DB switch to OFF. With the switch OFF, a negative voltage is normally present at the

preamp output, which will position the recorder stylus offscale.

3-14. OPERATION

3-15. Set RESP TIME/CAL DB switch to OFF. Connect input signal to preamplifier. For applications where preamplifier

is installed in Sanborn recorder, the output signal is displayed on recorder chart paper. For applications where the

preamplifier output is to be monitored with an oscilloscope or voltmeter, the output is available from the preamplifier front

panel OUTPUT jack, or from a rear connector on the preamplifier power supply.

3-16. Set the DB SPAN switch to the 50 dB or 100 dB position, depending on the expected range of input signal

amplitudes.

-4-

TM 11-6625-2872-14&P

3-17. 50 dB SPAN OPERATION.

3-18. Set the RANGE switch to the position which corresponds to the minimum expected signal level. See examples 1

and 2.

EXAMPLE 1: Minimum expected signal level 10 mnV rms. This corresponds to a -40 dBV signal level (see Table 3-1).

Set the RANGE switch to the -40 dBV position. The full scale signal level is 50 dB higher:

-40 dBV

add +50 dB

+10 dBV = Full scale input signal = 3.16 volts rms

EXAMPLE 2: Minimum expected signal level .5 volt rms. This corresponds to a -6 dBV signal level. Since there is no -

6 dBV switch position, set the switch to the next lower step, which is -10 dBV. The full scale signal level is 50 dB higher:

-10 dBV

add +50 dB

-40 dBV Full scale input signal = 100 volts rms

3-19. Set the RESP TIME/CAL DB switch to the FAST or SLOW position, depending on the signal bandwidth, and the

detection response) time desired. (For FAST response, the preamp) bandwidth is 500 to 100,000 Hz. For SLOW

response, bandwidth is 5 to 100,000 Hz.)

3-20. For 50 division chart paper, the calibration is 1 dB/div. The bottom division on the chart represents the bottom

scale signal level in dB indicated on the RANGE switch.

3-21. 100 dB SPAN OPERATION.

3-22. Only the four RANGE switch positions outlined in red (-80, -70, -60, -50) are used for the 100 dB span. Set the

RANGE switch to the position which corresponds to the expected minimum signal level.

EXAMPLE 1: Minimum expected signal is 1 mV rms. This corresponds to a -60 dBV level (see Table 3-1). Set RANGE

switch to the - 6OdBV bottom scale position. The full scale signal level is l00dB higher:

- 60 dBV

add +100 dB

+ 40 dBV = Full scale input signal = 100 volts rms

EXAMPLE 2: Minimum expected signal is

500 mV rms. This corresponds to a -66 dBV level. Set the RANGE switch to the next lower step, which is the -70 dBV

bottom scale position. The full scale signal level is 100 dB higher:

- 70 dBV

add +100 dB

+ 30 dBV = Full scale input signal = 31.6 volts rms

3-23. Set the RESP TIME/CAL DB switch to the FAST or SLOW position, depending on the signal blind bandwidth, and

the detection response time desired. (For FAST response, the preamp bandwidth is 500 to 100,000 Hz. For SLOW

response, bandwidth is 5 to 100,000 Hz.)

3-24. For 50 division chart paper, the calibration is 2 dB/div. The bottom division on the chart represents the bottom

scale signal level in dBV indicated on the RANGE switch.

3-25. OPERATION WITH MONITORING INSTRUMENTS.

3-26. When the preamplifier output is connected only to a monitoring instrument such as a dc voltmeter or oscilloscope,

perform the balancing (Section 3-9) and calibration (Section 3-11) procedure as indicated. Bottom scale output refers to

0 volts preamplifier output. Full scale output is -5 volts preamplifier output. The 50 dB span calibration is .1 volts/dB.

The 100 dB span calibration is .05 volts/dB.

3-27. SIMULTANEOUS RECORDING AND MONITORING OF 8808A OUTPUT.

3-28. To simultaneously record and monitor the 8808A output signal, perform the balancing and calibration procedure

using the recorder. The dc voltmeter, oscilloscope, or other monitoring instrument connected to the output of the preamp

will read approximately -2.5 volts for a bottom scale input signal, and approximately +2.5 volts for a full scale input

signal. The monitor instrument calibration is .1 V/dB on the 50 dB span, and .05 V/dB on the 100 dB span.

-5-

TM 11-6625-2872-14&P

SECTION IV

PRINCIPLES OF OPERATION

4-1. The 8808A Log Level Preamplifier is designed to produce a logarithmic output (in decibel units) on a linear scale for

a wide dynamic range (100 dB) of input signals. The wide dynamic range is achieved by the use of a combination of

series and shunt successive detector stages. The block diagram (Figure 4-1) shows a simple series of successive

detector stages with logarithmic compression networks, similar to those used in the 8808A.

4-2. Each stage consists of a linear amplifier having a gain of 16-2/3 dB. Limiting diodes at the input of each stage

prevent amplifier saturation. The full-wave detector output drives a logarithmic response shaping network. The outputs

of all stages are connected to a summing resistor. This series of stages handles the first 50 dB of amplifier signal input.

For 100 dB span operation, a second series of successive detectors covers the remaining 50 dB of signal range.

4-3. Signal flow as shown in Figure 4-1 is as follows: A small ac signal appearing at the input is amplified by stage 3, but

not sufficiently to provide detector output. The signal is further amplified by stage 2, but is still not sufficient amplitude to

detect. The signal is amplified by stage 1 to a level sufficient to operate the first detector. The output of the fullwave

detector is compressed by a three-line segment logarithmic compression network. All compression network outputs are

connected to the summing resistor. As the input level increases, successive compression in stages 2 and 3 perform a

similar function, feeding their output to the summing junction.

4-4. The very wide dynamic range of the 8808A is made possible by the progressive summing of the outputs of each of

the detector stages, which by themselves operate linearly over a 16-2/3dB range.

4-5. The overall block diagram for the 8808A is shown in Figure 4-2. A signal at the input sees the input Attenuator

which is followed by a differential, low noise operational amplifier using field effect transistors. The amplifier output is

connected to a series of detector and compressor networks to provide the first 50 dB of operating range. A shunt signal

path with a hybrid emitter follower drives the lower series of detector networks for the remaining, 50 dB of signal level.

4-6. The detector outputs are summed into a balanced dc amplifier. The SPAN BALANCE, control and zero suppression

circuit outputs are also summed into the balanced amplifier. The action of the SPAN BALANCE control is to produce the

same bottom scale output from the dc amplifier on the 50 dB and 100 dB spans. The zero suppression circuit works in

conjunction with the input Attenuator.

4-7. The DB SPAN switch circuit is located in the feedback loop of the balanced dc amplifier to produce a 2:1 gain

change in the amplifier output, depending on the setting of the SPAN switch.

4-8. The output of the balanced amplifier is fed to a shunt gain control, followed by the output differential to single-ended

dc amp which has a dc signal summed in from the LOG ZERO control to set log zero level.

ELECTRICAL SAFETY

The electrical safety of this product has been considered in its design and production, and its

construction has employed techniques and components in accordance with the National Electrical

Code and Underwriters Laboratories, Inc. These safety features apply only if the product is

connected to a primary power distribution system which provides adequate grounding and is

installed and maintained in accordance with the National Electrical Code. When this product is

interconnected with other electrical appliances in its normal operation, it is important that these

other appliances also be provided with adequate grounding protection, where required, if they are,

in turn, connected to a primary power source. Faults occurring in any interconnected appliance

can degrade the safety of this product by means of the electrical interconnections necessary for its

normal systems operation. Recommendations indicating some of the accessory appliances which

may be used with this product are given elsewhere in this publication.

-6-

TM 11-6625-2872-14&P

Figure 4-1. 8808A Successive Detector Stages

Figure 4-2. 8808A Block Diagram

-7-

TM 11-6625-2872-14&P

SECTION V

REPLACEABLE PARTS

5-1. INTRODUCTION.

5-2. This section contains information for locating and ordering replacement parts. Table 5-1 provides the following

information for each item.

a. Lists electrical parts in alpha-numeric order of their reference designators.

b. The Sanborn stock number.

c. The part description.

d. Lists miscellaneous parts in numerical order

5-3. ORDERING INFORMATION.

5-4. To order a replacement part, note the part number and then cross reference that part number to the National Stock

Number in table 5-2; then order through normal ordering channels. If the part number does not have a National Stock

Number, then order the part through normal ordering channels using the commercial part number. Specify the following

information for each part:

a. Model and s/n of the instrument.

b. Sanborn stock number.

c. Circuit reference designator.

d. Description.

5-5. To order a part not listed in the tables, give a complete description of the part and include its function and location.

-8-

TM 11-6625-2872-14&P

Table 5-1. Reference Designation Index

Circuit

Reference

Assembly

Location

Part Number

Description

END ITEM

8808A

LOG LEVEL PREAMPLIFIER

PRINTED CIRCUIT BOARD ASSY.

PRINTEID CIRCUIT BOARD ASSY.

SWITCH ASSEMBLY

08808-60020

08808-60030

08808-60050

ACCESSORY

MISCELLANEOUS

Page 15

Page 16

8PA-6

Capacitor, 100 pF

Same, as C1

0121-0163

0160-2388

8PA-35

0160-2386

0121-0160

0160-2384

0121-0160

0160-2383

8C-61

0160-2387

8B-201

8B-213

8B-145

0180-0374

8B-68

0180-0022

8T-31

0180-0374

0180-0195

0180-0022

8T-31

0180-0374

0180-0195

0180-0022

8B-68

Capacitor, 7-45 pF

Capacitor, 47 MFD 400V

Capacitor, 1000 pF 5%

Capacitor, 470 pF

Capacitor, 210-1000 pF

Capacitor, 120 pF

Same as C7

Capacitor, 100 pF 1%

Capacitor, 20 MFD 20V

Same as C11

Capacitor, 1000 pF 1%

Capacitor, .0047 MFD 10%

Capacitor, .0033 MFD

Capacitor, .005 MFD 5%

Capacitor, 10 MFD 20V

Capacitor, .01 MFD

Capacitor, 3.9 MFD 35V

Capacitor, .22 MFD

Same as C17

Capacitor, .33 MFD

Same as C19

Same as C20

Same as C17

Same as C22

Same as C19

Same as C18

Capacitor, 7-45 pF

Capacitor, 150 pF

Same as C18

Same as C19

Same as C17

Same as C18

Same as C19

Same as C20

Same as C17

Same as C18

Same as C19

Same as C20

Same as C17

Same as C18

Same as C19

C10

C11

C12

C13

C14

C15

C16

C17

C18

C19

C20

C21

C22

C23

C24

C25

C26

C27

C28

C29

C30

C31

C32

C33

C34

C35

C36

C37

C38

C39

C40

C41

C42

C43

C44

8B-68

0121-0163

0160-2385

8B-68

0180-0022

0180-0374

8B-68

0180-0022

8T-31

0180-0374

8B-68

0180-0022

8T-31

0180-0374

8B-68

0180-0022

-9-

TM 11-6625-2872-14&P

Table 5-1. Reference Designation Index (Cont.)

Circuit

Reference

C45

C46

C47

C48

C49

C50

C51

C52

C53

C54

C55

C56

C57

C58

C59

C61

CR1

CR2

CR3

CR4

CR5

CR6

CR7

Assembly

Location

Part Number

Description

5080-3722

5080-3723

5080-3722

5080-3723

8B-68

8B-213

0180-1862

8B-181

8E-28

8E-21

16A-79

16A-83

16A-79

Capacitor, 27 MFD 10V

Capacitor, .22 MFD

Same as C45

Same as C46

Capacitor, .01 MFD

Same as C49

Same as C15

Capacitor, 120 MFD 15V

Same as C53

Capacitor, 120 MFD 15V

Same as C55

Capacitor, .22 MFD

Capacitor 0033 MFD

Same as C58

Capacitor, 68 pF

Diode

Same as CR1

Diode (3 Pellet)

Same as CR6

Diode

Same as CR8

CR8

CR9

CR10

CR11

CR12

CR13

CR14

CR15

CR16

CR17

CR18

CR19

CR20

CR21

CR22

CR23

CR24

CR25

CR26

CR27

CR28

CR29

CR30

CR31

CR32

CR33

CR34

CR35

CR36

CR37

CR38

CR39

16A-79

Same as CR8

1901-0378

1910-0016

16A-45A

1901-0378

1901-0377

16A-79

Diode, Silicon Stabistor (2 Pellet)

Same as CR12

Diode, Germanium

Same as CR14

Diode

Same as CR12

Diode, Silicon Stabistor (3 Pellet)

Same as CR8

16A-79

Same as CRR

Same as CR8

1901-0378

1910-0016

16A-45A

1901-0378

1901-0377

16A-79

1901-0378

16A-45A

1901-0378

Same as CR12

Same as CR14

Same as CR16

Same as CR12

Same as CR18

Same as CR8

Same as CR12

Same as CR16

Same as CR12

-10-

TM 11-6625-2872-14&P

Table 5-1. Reference Designation Index (Cont.)

Circuit

Reference

CR40

CR41

CR42

CR43

CR44

CR45

CR46

CR47

CR48

CR49

CR50

CR51

CR52

CR53

CR54

CR55

CR56

CR57

CR58

CR59

CR60

CR61

CR62

CR63

CR64

CR65

CR66

CR67

CR68

CR69

CR70

CR71

CR72

CR73

CR74

CR75

CR76

CR77

CR78

CR79

CR80

Assembly

Location

Part Number

Description

1901-0377

1910-0016

16A-45A

1901-0378

16A-79

1901-0378

1910-0016

16A-45A

1901-0378

1901-0377

16A-79

Same as CR18

Same as CR14

Same as CR16

Same as CR12

Same as CR8

Same as CR12

Same as CR14

Same as CRI4

Same as CR16

Same as CR12

Same as CR18

Same as CR8

Same as CR12

Same as CR14

Same as CR16

Same as CR12

Same as CR18

Same as CR8

Same as CR12

Same as CR14

Same as CR16

Same as CR12

Same as CR18

Diode

16A-79

1901-0378

1910-0016

16A-45A

1901-0378

1901-0377

16A-79

1901-0378

1910-0016

16A-45A

1901-0378

1901-0377

16A-45A

10G16-IMX

10G2-22FX

1855-0031

1854-0202

16T-81

16T-79

16T-50

16T-79

16T-50

16T-79

16T-50

Same as CR78

Connector, 16-pin

Mini-Jack

Transistor, Field Effect

Transistor, 2N3390

Same as Q2

Transistor, SM9143

Same as Q4

Transistor, 2N3391

Transistor, 2N1309

Same as Q6

Q1A, 1B

Q10

Q11

Same as Q7

Same as Q6

Same as Q7

-11

TM 11-6625-2872-14&P

Table 5-1. Reference Designation Index (Cont.)

Circuit

Reference

Q12

Q13

Q14

Q15

Q16

Q17

Q18

Q19

Q20

Q21

Q22

Q23

Q24

Q25

Q26

Q27

Q28

Q29

Assembly

Location

Part Number

16T-78

16T-76

16T-79

16T-50

16T-79

16T-50

16T-79

Description

Transistor, 2N3393

Transistor, 53-10

Same as Q6

Same as Q7

Same as Q6

Same as Q7

Same as Q6

Same as Q7

Transistor, 54-23

Same as Q20

Same as Q13

Same as Q12

Same as Q4

Transistor, 2N3053

Same as Q27

16T-50

5080-3724

16T-76

16T-78

16T-81

16T-61

Same as Q27

50AB-155J

50AB-335J

0698-4981

50E-124F

50E-825-3F

50E-976-3F

50E-205F

50AB-472J

50E-503F

56PA-17

50E-403F

50E-503F

50AB-472J

0757-0309

50E-104F

50E-204F

50AB-472J

50AB-222J

50AB-471J

50E-316-2F

50AB-331J

50AB--221J

50E-101F

50AB-223J

50AB-472.J

50E-133-2F

50E-202F

50AB-472J

50AB-332J

50E-153F

50E-104F

50AB-152J

50E-504F

50E-353F

Resistor, 1.5 Meg ±5%

Resistor, 3.3 Meg ±5%

Resistor, 32.4K 1%o

Resistor, 120K 1%

Resistor, 825K 1'%

Resistor, 976K 1%

Resistor, 2 Meg 1%

Resistor, 4.7K 5%

Resistor, 50K 1%

Potentiometer, 250 Ohm

Resistor, 40K 1%

Same as R9

R10

R11

R12

R13

R14

R15

R16

R17

R18

R19

R20

R21

R22

R23

R24

R25

R26

R27

R28

R29

R30

R31

R32

R33

R34

R35

R36

R37

Same as R8

Resistor, 61.9K 1%

Resistor, I00K%

Same as R15

Resistor, 200K 1%

Same as R8

Resistor, 2.2K 5%

Resistor, 470 Ohm 5%

Resistor, 31.6K 1%

Resistor, 330 Ohm 5%

Resistor, 220 Ohm 5%

Resistor, 100 Ohm 1%

Resistor, 22K ±5%

Resistor. 4.7K ±5%

Resistor, 13.3K ±1%

Resistor, 2K ±1%

Same as R26

Resistor, 3.3K ±5%

Resistor, 15K ±1%

Same as R31

Resistor, 100K ±1%

Same as R33

Resistor, 1. 5K 5%

Resistor, 500K ±1%

Resistor, 35K ±1%

-12-

TM 11-6625-2872-14&P

Table 5-1. Reference Designation Index (Cont.)

Circuit

Reference

R38

R39

R40

R41

R42

R43

R44

R45

R46

R47

R48

R49

R50

R51

R52

R53

R54

R55

R56

R57

R58

R59

R60

R61

R62

R63

R64

R65

R66

R67

R68

R69

R70

R71

R72

R73

R74

R75

R76

R77

R78

R79

R80

R81

R82

R83

R84

R85

R86

R87

R88

R89

R90

R91

R92

R93

R94

Assembly

Location

Part Number

Description

50E-105F

50AB-223J

50AB-472J

50E-133-2F

50E-202F

50AB-472J

50AB-332J

50E-153F

50E-104F

50E-504F

50E-353F

50E-105F

50AB-223J

50AB-472J

50E-133-2F

50E-202F

50AB-472J

50AB-332J

50E-153F

50E-104F

50E-105F

50E-104F

50E-105F

50E-185F

50E-204F

50AB-224J

50E-153F

50E-104F

50E-504F

50E-204F

50E-105F

50AB-223J

50AB-472J

50E-133-2F

50E-202F

50AB-472J

50AB-332J

50E-153F

50E-104F

50E-504F

50E-353F

50E-105F

50AB-223J

50AB-472J

Resistor, 1 Meg ±1%

Same as R38

Sane as R25

Same as R26

Same as R27

Same as R28

Same as R26

Same as R30

Same as R31

Same as R33

Same as R36

Same as R37

Same as R38

Same as R25

Same as R26

Same as R27

Same as R28

Same as R26

Same as R30

Same as R31

Same as R33

Same as R38

Same as R33

Same as R38

Resistor, 1.8 Meg 1%

Same as R17

Resistor, 220K 5%

Same as R31

Same as R33

Same as R36

Resistor, 200K ±1%

Same as R38

Same as R25

Same as R26

Same as R27

Same as R28

Same as R26

Same as R30

Same as R31

Same as R33

Same as R36

Same as R37

Same as R38

Same as R25

Same as R26

-13-

TM 11-6625-2872-14&P

Table 5-1. Reference Designation Index (Cont.)

Circuit

Reference

R95

R96

R97

Assembly

Location

Part Number

Description

Same as R27

Same as R28

Same as R26

Same as R30

Same as R31

Same as R33

Same as R36

Same as R37

Same as R38

Same as R25

Same as R26

Resistor, 10K 1%

Same as R28

Same as R26

Potentiometer, 10K

Same as R30

Same as R31

Same as R33

Same as R36

Same as R37

50E-133-2F

50E-202F

50AB-472J

50AB-332J

50E-153F

50E-104F

50E-504F

50E-353F

50E-105F

50AB-223J

50AB-472J

50E-103F

50E-202F

50AB-472J

56PA-47

50AB-332J

50E-153F

50E-104F

50E-504F

50E-353F

50E-105F

50AB-221J

50AB-123J

5OAB-474J

50AB-474J

50AB-123J

50E-103F

50AB-682J

56PA-47

R98

R99

R100

R101

R102

R103

R104

R105

R106

R107

R108

R109

R110

R111

R112

R113

R114

R115

R116

R117

R118

R119

R120

R121

R122

R123

R124

R125

R126

R127

R128

R129

R130

R131

R132

R133

R134

R135

R136

R137

R138

R139

R140

R141

R142

R143

R144

R145

R146

R147

R148

R149

R150

R151

Same as R38

Same as R23

Resistor, 12K 5%

Resistor, 470K 5%

Same as R124

Same as R123

Resistor, 10K l%

Resistor, 6.8K 5%

Potentiometer, 10K

Same as R9

Same as R24

Resistor, 158 Ohm 1%

Same as R10

Potentiometer, 2. 5K

Resistor, 2K 1%

Resistor, 18K 1%

Resistor, 50 Ohm 1%

Resistor, 2. 5K 1%

Same as R138

Resistor, 50K 3%

Potentiometer, 1000 Ohm (SPAN BAL)

Resistor, 250K 1%

Resistor, 15K 5%

Same as R147

Same as R146

Resistor, 25K 1%

Resistor, 120K 5%

50E-503F

50E-1O1F

50E-158-OF

56PA-17

56PA-37

50E-202F

0757-1011

50E-50OF

50E-252F

50E-50OF

50E-500F

0811-1797

56S-8

50E-254F

50AB-153J

50E-254F

50E-253F

50AB-124J

-14-

TM 11-6625-2872-14&P

Table 5-1. Reference Designation Index Cont.

Circuit

Reference

R152

R153

R154

R155

R156

R157

R158

R159

R160

R161

R162

R163

R164

R165

R166

R167

R168

R169

R170

R171

R172

R173

R174

R175

R176

R177

R178

R179

R180

R181

Assembly

Location

Part Number

Description

Same as R150

50E-253F

50AB-103J

50AB-392J

0811-1797

50E-303F

50AB-123J

50E-303F

0811-1797

50E-104-2F

50E-752F

50E-503F

50E-103F

56S-35

50E-253F

50E-103F

50E-316-2F

50AB-472J

50AB-123J

50AB-272J

50AB-121J

50E-403F

56E-7

Resistor, 10K 5%

Resistor, 3.9K 5%

Same as R144

Resistor, 30K 1%

Same as R123

Same as R156

Same as R144

Resistor, 10.4K 1%

Resistor, 7.5K 1%

Same as R9

Same as R127

Potentiometer, 250K (GAIN)

Same as R150

Same as R127

Same as R21

Same as R8

Same as R123

Resistor, 2.7K 5%

Resistor, 120 Ohm 5%

Same as R11

Potentiometer, 50K (LOG ZERO)

Same as R11

Resistor, 10 Ohm s5%

Same as R178

Resistor, 150K 1%

Resistor, 5.6K 5%

50E-403F

50AB-1OOJ

50E-154F

50AB-562J

62B-219

62B-220

62D-48

Switch, Rotary

Switch, Wafer 3-Section, 9-Position

Switch, Toggle DPDT

56T-11

Thermister, 20K

ACCESSORY

Phone Plug

10G2-22MW

-15-

TM 11-6625-2872-14&P

Table 5-1. Reference Designation Index (Cont.)

Assembly

Location

Quantity

Part Number

Description

MISCELLANEOUS

Knob

0370-0077

652-65

816-64

833-5 P1

833-6 P1

860-3002

860-3003

860-4005

08800-20010

08808-00010

08808-00050

752-427

01260-20501

01260-20601

752-428

Nameplate (08808-00020)

Plate, Connector

Stand-Off

Nut

Chassis, Upper

Chassis, Lower

Plate, Side

Handle

Panel, Front

Bracket, Printed Circuit Board

Printed Board

Heat Sink, Bottom

Heat Sink, Top

Printed Board

SHAFT LOCK (1/8 SHAFT)_817-C1

817-5

817-2

7-7

817-6

817-1

81D-4-3/2Z

81D-4-2Z

Bushing, Shaft Lock

Knob, Shaft Lock

Washer, Shaft Lock (Lower)

Washer, Shaft-Lock (Upper)

Nut, Shaft-Lock

3/32 x 4-40 Allen Head Set Screw

1/8" x 4-40 Allen Head Set Screw

SHAFT LOCK (1/4" SHAFT) 817-C2

817-4

817-3

817-7

817-6

817-1

81D-4-3/2Z

81D-4-2Z

Bushing, Shaft-Lock

Knob, Shaft-Lock

Washer, Shaft-Lock (Lower)

Washer, Shaft-Lock (Upper)

Nut, Shaft-Lock

3/32 x 4-40 Allen Head Set Screw

1/8" x 4-40 Allen Head Set Screw

-16-

TM 11-6625-2872-14&P

Table 5-2.

PART NUMBER - NATIONAL STOCK NUMBER

CROSS REFERENCE INDEX

PART

NUMBER

NATIONAL

STOCK NO.

PART

NUMBER

NATIONAL

STOCK NO.

FSCM

0180-0022

0180-0195

0180-0374

0370-0077

0370-1107

0698-3420

0757-0309

0757-0837

0757-0843

1910-0016

5080-3724

8808A

28480

5910-00-538-3597

5910-00-444-6642

5910-00-931-7050

5355-00-767-9444

5355-01-011-4975

5905-00-931-4067

5905-00-632-5238

5905-00-850-2180

5905-00-830-6751

5961-00-954-9182

5961-00-105-4694

6625-00-134-3557

Foldout figure 5-1 is located in back of the manual.

-17-

TM 11-6625-2872-14&P

APPENDIX A

REFERENCES

DA Pam 310-4

Index of Technical Publications: Technical Manuals, Technical Bulletins, Supply

Manuals (Types 7, 8, and 9), Supply Bulletins, and Lubrication Orders.

DA Pam 310-7

US Army Equipment Index of Modification Work Orders.

TB 11-6625-2751-35

Calibration Procedures for Dual Channel Recorder RO-460(V1)/U (HP Model 7702B)

and Oscillographic Recorder (HP Model 7418A); Preamplifier Power Supply (HP

8848A); Preamplifier Plug-In Unit PL-1306A/U (HP Model 8803A); and Preamplifier

Plug-In Units (HP Models 8801A, 8802A, 8805A, and 8808A).

TB 43-180

Calibration Requirements for the Maintenance of Army Materiel.

TB 385-4

Safety Precautions for Maintenance of Electrical/Electronic Equipment.

TM 11-6625-537-14-1

Operator's, Organizational, Direct Support and General Support Maintenance Manual:

Electronic Voltmeters.ME-202A/U (NSN 6625-00-709-0288) and ME-202B/U (NSN

6625-00-972-4046).

TM 11-6625-654-14

Operator's, Organizational, Direct Support, and General Support Maintenance Repair

Parts and Special Tools List (Including Depot Maintenance Repair Parts and Special

Tools List) for Multimeter AN/USM-223.

TM 11-6625-683-15

TM 11-6625-2658-14

TM 38-750

Operator's, Organizational, Direct Support, General Support and Depot Maintenance

Manual: Signal Generator AN/URM-127 (NSN 6625-00-783-5965).

Operator's, Organizational, Direct Support, and General Support Maintenance Manual

for Oscilloscope AN/USM-281C (NSN 6625-00-106-9622).

The Army Maintenance Management System (TAMMS)

A-1

TM 11-6625-2872-14&P

TM 740-90-1

TM 750-244-2

Administrative Storage of Equipment.

Procedures for Destruction of Electronics Materiel to Prevent Enemy Use (Electronics

Command).

A-2

TM 11-6625-2872-14&P

APPENDIX D

MAINTENANCE ALLOCATION

Section I. INTRODUCTION

D-1. General

This appendix provides a summary of the maintenance operations for the AM-6681 (V)/U. It authorizes categories of

maintenance for specific maintenance functions on repairable items and components and the tools and equipment

required to perform each function. This appendix may be used as an aid in planning maintenance operations.

D-2. Maintenance Function

Maintenance functions will be limited to and defined as follows:

a. Inspect. To determine the serviceability of an item by comparing its physical, mechanical, and/or electrical

characteristics with established standards through examination.

b. Test. To verify serviceability and to detect incipient failure by measuring the mechanical or electrical characteristics

of an item and comparing those characteristics with prescribed standards.

c. Service. Operations required periodically to keep an item in proper operating conditions, i.e., to clean

(decontaminate), to preserve, to drain, to paint, or to replenish fuel, lubricants, hydraulic fluids, or compressed air

supplies.

d. Adjust To maintain, within prescribed limits, by bringing into proper or exact position, or by setting the operating

characteristics to the specified parameters.

e. Align. To adjust specified variable elements of an item to bring about optimum or desired performance.

f. Calibrate. To determine and cause corrections to be made or to be adjusted on instruments or test measuring and

diagnostic equipments used in precision measurement. Consists of comparisons of two instruments, one of which is a

certified standard of known accuracy, to detect and adjust any discrepancy in the accuracy of the instrument being

compared.

g. Install. The act of emplacing, seating, or fixing into position an item, part, module (component or assembly) in a

manner to allow the proper functioning of the equipment or system.

h. Replace. The act of substituting a serviceable like type part, subassembly, or module (component or assembly) for an

unserviceable counterpart.

i. Repair. The application of maintenance services (inspect, test, service, adjust, align, calibrate, replace) or other

maintenance actions (welding, grinding, riveting, straightening, facing, remachining, or resurfacing) to restore

serviceability to an item by correcting specific damage, fault, malfunction, or failure in a part, subassembly, module

(component or assembly), end item, or system.

j. Overhaul. That maintenance effort (service/action) necessary to restore an item to a completely

serviceable/operational condition as prescribed by maintenance standards (i.e., DMWR) in appropriate technical

publications. Overhaul is normally the highest degree of maintenance performed by the Army. Overhaul does not

normally return an item to like new condition.

k. Rebuild. Consists of those services actions necessary for the restoration of unserviceable equipment to a like new

condition in accordance with original manufacturing standards. Rebuild is the highest degree of materiel maintenance

applied to Army equipment. The rebuild operation includes the act of returning to zero those age measurements (hours,

miles, etc.) considered in classifying Army equipments/components.

D-1

TM 11-6625-2872-14&P

D-3. Column Entries

a. Column 1, Group Number. Column 1 lists group numbers, the purpose of which is to identify components,

assemblies, subassemblies, and modules with the next higher assembly.

b. Column 2, Component/Assembly. Column 2 contains the noun names of components, assemblies, subassemblies,

and modules for which maintenance is authorized.

c. Column 3, Maintenance Functions. Column 3 lists the functions to be performed on the item listed in column 2.

When items are listed without maintenance functions, it is solely for purpose of having the group numbers in the MAC

and RPSTL coincide.

d. Column 4, Maintenance Category. Column 4 specifies, by the listing of a "worktime" figure in the appropriate

subcolumn(s), the lowest level of maintenance authorized to perform the function listed in column 3. This figure

represents the active time required to perform that maintenance function at the indicated category of maintenance. If the

number or complexity of the tasks within the listed maintenance function vary at different maintenance categories,

appropriate "worktime" figures will be shown for each category. The number of task-hours specified by the "worktime"

figure represents the average time required to restore an item (assembly, subassembly, component, module, end item or

system) to a serviceable condition under typical field operating conditions. This time includes preparation time,

troubleshooting time, and quality assurance/quality control time in addition to the time required to perform the specific

tasks identified for the maintenance functions authorized in the maintenance allocation chart. Subcolumns of column 4

are as follows:

C - Operator/Crew

O - Organizational

F - Direct Support

H - General Support

D - Depot

e. Column 5, Tools and Equipment. Column 5 specifies by code, those common tool sets (not individual tools) and

special tools, test, ,and support equipment required to perform the designated function.

f. Column 6, Remarks. Column 6 contains an alphabetic code which leads to the remark in section IV, Remarks, which

is pertinent to the item opposite the particular code.

D-4. Tool and Test Equipment Requirement (sect III)

a. Tool or Test Equipment Reference Code. The numbers in this column coincide with the numbers used in the tools

and equipment column of the MAC. The numbers indicate the applicable tool or test equipment for the maintenance

functions.

b. Maintenance Category. The codes in this column indicate the maintenance category allocated the tool or test

equipment.

c. Nomenclature. This column lists the noun name and nomenclature of the tools and test equipment required to

perform the maintenance functions.

d. National/NATO Stock Number. This column lists the National/NATO stock number of the specified tool or test

equipment.

e. Tool Number. This column lists the manufacturer's part number of the tool followed by the Federal Supply Code for

manufacturers (5-digit) in parentheses.

D-5. Remarks (sect IV)

Not applicable.

D-2

TM 11-6625-2872-14&P

SECTION II. MAINTENANCE ALLOCATION CHART

FOR

PLUG-IN AMPLIFIER AM-6681(V)1/U

(1)

(2)

(3)

(4)

(5)

(6)

TOOLS

GROUP

COMPONENT/ASSEMBLY

MAINTENANCE MAINTENANCE CATEGORY AND

NUMBER

FUNCTION

EQPT REMARKS

PLUG-IN AMPLIFIER AM-6681(V)1/U

Inspect

0.5

Visual

only

Service

Adjust

Test

0.5

1.0

1,2,3

1 thru 4

Repair

Overhaul

2.0

D-3

TM 11-6625-2872-14&P

SECTION III TOOL AND TEST EQUIPMENT REQUIREMENTS

FOR

PLUG-IN AMPLIFIER AM-6681(V) 1/U

TOOL OR TEST MAINTENANCE

NATIONAL/NATO

STOCK NUMBER TOOL NUMBER

EQUIPMENT

REF CODE