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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
SAFETY STEPS TO FOLLOW IF SOMEONE IS THE VICTIM OF ELECTRICAL SHOCK
DO NOT TRY TO PULL OR GRAB THE INDIVIDUAL
IF POSSIBLE, TURN OFF THE ELECTRICAL POWER
IF YOU CANNOT TURN OFF THE ELECTRICAL POWER, PULL, PUSH, OR LIFT THE
PERSON TO SAFETY USING A DRY WOODEN POLE OR A DRY ROPE OR SOME
OTHER INSULATING MATERIAL
SEND FOR HELP AS SOON AS POSSIBLE
AFTER THE INJURED PERSON IS FREE OF CONTACT WITH THE SOURCE OF
ELECTRICAL SHOCK, MOVE THE PERSON A SHORT DISTANCE AWAY AND
IMMEDIATELY START ARTIFICIAL RESUSCITATION
5
1
2
3
4
5
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
No. 11-6625-2872-14&P WASHINGTON, DC, 12 March 1981
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.
i
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TM 11-6625-2872-14&P
TABLE OF CONTENTS
Paragraph Page
SECTION 0. INTRODUCTION
Scope...................................................................................................... 0-1 0-1
Indexes of Publications . . . . ............................................................... 0-2 0-1
Maintenance Forms, Records, and
Reports ............................................................................................. 0-3 0-1
Reporting Equipment Improvement
Recommendations (EIR).......................................................................... 0-4 0-1
Administrative Storage ............................................................................ 0-5 0-1
Destruction of Army Electronics
Materiel............................................................................................. 0-6 0-1
I. GENERAL INFORMATION
Description .............................................................................................. 1-1 1
II. INSTALLATION
Portable Case or Rack Mounting ............................................................. 2-1 3
Installation in Sanborn Recording
Systems ............................................................................................ 2-5 3
III. OPERATION
Operating Controls................................................................................... 3-1 3
Balancing ................................................................................................ 3-9 4
Calibration............................................................................................... 3-11 4
Alternate Calibration Procedure............................................................... 3-12 4
Operation ................................................................................................ 3-14 4
50 dB Span Operation ............................................................................. 3-17 5
100 dB Span Operation ........................................................................... 3-21 5
Operation with Monitoring Instruments..................................................... 3-25 5
Simultaneous Recording and Monitoring
of 8808A Output................................................................................ 3-27 5
IV. PRINCIPLES OF OPERATION
Output ..................................................................................................... 4-1 6
Stage Description .................................................................................... 4-2 6
Signal Flow.............................................................................................. 4-3 6
Dynamic Range....................................................................................... 4-4 6
Block Diagram Information ...................................................................... 4-5 6
Detector Outputs ..................................................................................... 4-6 6
DB SPAN Switch Circuit .......................................................................... 4-7 6
LOG ZERO Level Setting ........................................................................ 4-8 6
V. REPLACEABLE PARTS
Introduction.............................................................................................. 5-1 8
Ordering Information................................................................................ 5-3 8
ii
TM 11-6625-2872-14&P
TABLE OF CONTENTS - Continued
Page
APPENDIX A. REFERENCES.................................................................................................... A-1
B. COMPONENTS OF END ITEM LIST (COEIL)
(Not applicable)
C. BASIC ISSUE ITEMS LIST (BIIL)
(Not applicable)
D. MAINTENANCE ALLOCATION
Section I. Introduction.......................................................................................................... D-1
II. Maintenance Allocation Chart for Plug-In
Amplifier AM-6681(V)1/U .............................................................................. D-3
III. Tool and Test Equipment Requirements for
Plug-In Amplifier AM-6681(V)1/U .................................................................. D-4
iii
TM 11-6625-2872-14&P
LIST OF ILLUSTRATIONS
Number Page
1-1 8808A Log Level Preamplifier .................................................................................................... 1
4-1 8808A Successive Detector ...................................................................................................... 7
4-2 8808A Block Diagram ................................................................................................................ 7
FO 5-1 Model 8808A Log Level Schematic ............................................................................................ In back
of manual
LIST OF TABLES
Number Page
1-1 Specifications ............................................................................................................................ 2
3-1 Bottom and Full Scale Signal Levels.......................................................................................... 3
5-1 Reference Designation Index ..................................................................................................... 9
5-2 Part Number - National Stock Number
Cross Reference Index ........................................................................................................ 17
iv
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 µV 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 µV, 320 µV, 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 µV, 320 µV, 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
Signal Output Jack J2: Plus (+) signal pin A
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.
3-3. DB SPAN switch selects either 50 dB or
100 dB maximum span between the bottom
scale and full scale input signal levels.
NOTE
On the 100 dB span, only the -
50, -60, -70, -80 RANGE switch
positions are used.
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-
50 DB SPAN
Range
Switch Bottom Scale Full Scale
Setting dBV Volts rms dBV Volts rms
0 01 V +50 316 V
-10 -10 .316V +40 100 V
-20 -20 .100V +30 31.6 V
-30 -30 31.6 mnV +20 10 V
-40 -40 10 mV +10 3.16 V
-50 -50 3.16 mV 01 V
-60 -60 1 mV -10 .316 V
-70 -70 316 µV-20 .1 V
-80 -80 100 µV-30 31.6 mV
100 DB SPAN
-50 -50 3.16 mV +50 316 V
-60 -60 1 mV +40 100 V
-70 -70 316 µV+30 31.6 V
-80 -80 100 µV+20 10 V
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 µV 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 4-2. 8808A Block Diagram
-7-
Figure 4-1. 8808A Successive Detector Stages
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 Assembly
Reference Part Number Description Location
END ITEM 8808A LOG LEVEL PREAMPLIFIER A1
08808-60020 PRINTED CIRCUIT BOARD ASSY. A2
08808-60030 PRINTEID CIRCUIT BOARD ASSY. A3
08808-60050 SWITCH ASSEMBLY A4
ACCESSORY Page 15
MISCELLANEOUS Page 16
C1 8PA-6 Capacitor, 100 pF A2
C2 8PA-6 Same, as C1 A2
C3 0121-0163 Capacitor, 7-45 pF A2
C4 0160-2388 Capacitor, 47 MFD 400V A2
C5 8PA-35 Capacitor, 1000 pF 5% A2
C6 0160-2386 Capacitor, 470 pF A2
C7 0121-0160 Capacitor, 210-1000 pF A2
C8 0160-2384 Capacitor, 120 pF A2
C9 0121-0160 Same as C7 A2
C10 0160-2383 Capacitor, 100 pF 1% A2
C11 8C-61 Capacitor, 20 MFD 20V A2
C12 8C-61 Same as C11 A2
C13 0160-2387 Capacitor, 1000 pF 1% A2
C14 8B-201 Capacitor, .0047 MFD 10% A2
C15 8B-213 Capacitor, .0033 MFD A2
C16 8B-145 Capacitor, .005 MFD 5% A2
C17 0180-0374 Capacitor, 10 MFD 20V A3
C18 8B-68 Capacitor, .01 MFD A3
C19 0180-0022 Capacitor, 3.9 MFD 35V A3
C20 8T-31 Capacitor, .22 MFD A3
C21 0180-0374 Same as C17 A3
C22 0180-0195 Capacitor, .33 MFD A3
C23 0180-0022 Same as C19 A3
C24 8T-31 Same as C20 A3
C25 0180-0374 Same as C17A3
C26 0180-0195 Same as C22 A3
C27 0180-0022 Same as C19 A3
C28 8B-68 Same as C18 A3
C29 8B-68 Same as C18 A3
C30 0121-0163 Capacitor, 7-45 pF A2
C31 0160-2385 Capacitor, 150 pF A2
C32 8B-68 Same as C18 A3
C33 0180-0022 Same as C19 A3
C34 0180-0374 Same as C17 A3
C35 8B-68 Same as C18 A3
C36 0180-0022 Same as C19 A3
C37 8T-31 Same as C20 A3
C38 0180-0374 Same as C17 A3
C39 8B-68 Same as C18 A3
C40 0180-0022 Same as C19 A3
C41 8T-31 Same as C20 A3
C42 0180-0374 Same as C17A3
C43 8B-68 Same as C18 A3
C44 0180-0022 Same as C19 A3
-9-
TM 11-6625-2872-14&P
Table 5-1. Reference Designation Index (Cont.)
Circuit Assembly
Reference Part Number Description Location
C45 5080-3722 Capacitor, 27 MFD 10V A2
C46 5080-3723 Capacitor, .22 MFD A2
C47 5080-3722 Same as C45 A2
C48 5080-3723 Same as C46 A2
C49 8B-68 Capacitor, .01 MFD A2
C50 8B-68 Same as C49 A2
C51 8B-68 Same as C49 A2
C52 8B-213 Same as C15 A2
C53 0180-1862 Capacitor, 120 MFD 15V A3
C54 0180-1862 Same as C53 A3
C55 0180-1862 Capacitor, 120 MFD 15V A2
C56 0180-1862 Same as C55 A2
C57 8B-181 Capacitor, .22 MFD A2
C58 8E-28 Capacitor 0033 MFD A2
C59 8E-28 Same as C58 A2
C61 8E-21 Capacitor, 68 pF A2
CR1 16A-79 Diode A2
CR2 16A-79 Same as CR1 A2
CR3 16A-79 Same as CR1 A2
CR4 16A-79 Same as CR1 A2
CR5 16A-79 Same as CR1 A2
CR6 16A-83 Diode (3 Pellet) A2
CR7 16A-83 Same as CR6 A2
CR8 16A-79 Diode A3
CR9 16A-79 Same as CR8 A3
CR10 16A-79 Same as CR8 A3
CR11 16A-79 Same as CR8 A3
CR12 1901-0378 Diode, Silicon Stabistor (2 Pellet) A3
CR13 1901-0378 Same as CR12 A3
CR14 1910-0016 Diode, Germanium A3
CR15 1910-0016 Same as CR14 A3
CR16 16A-45A Diode A3
CR17 1901-0378 Same as CR12 A3
CR18 1901-0377 Diode, Silicon Stabistor (3 Pellet) A3
CR19 16A-79 Same as CR8 A3
CR20 16A-79 Same as CRR A3
CR21 16A-79 Same as CR8 A3
CR22 16A-79 Same as CR8 A3
CR23 1901-0378 Same as CR12 A3
CR24 1901-0378 Same as CR12 A3
CR25 1910-0016 Same as CR14 A3
CR26 1910-0016 Same as CR14 A3
CR27 16A-45A Same as CR16 A3
CR28 1901-0378 Same as CR12 A3
CR29 1901-0377 Same as CR18 A3
CR30 16A-79 Same as CR8 A3
CR31 16A-79 Same as CR8 A3
CR32 16A-79 Same as CR8 A3
CR33 16A-79 Same as CR8 A3
CR34 1901-0378 Same as CR12 A3
CR35 1901-0378 Same as CR12 A3
CR36 16A-45A Same as CR16 A3
CR37 16A-45A Same as CR16 A3
CR38 16A-45A Same as CR16 A3
CR39 1901-0378 Same as CR12 A3
-10-
TM 11-6625-2872-14&P
Table 5-1. Reference Designation Index (Cont.)
Circuit Assembly
Reference Part Number Description Location
CR40 1901-0377 Same as CR18 A3
CR41 1910-0016 Same as CR14 A3
CR42 1910-0016 Same as CR14 A3
CR43 16A-45A Same as CR16 A3
CR44 1901-0378 Same as CR12 A3
CR45 16A-79 Same as CR8 A3
CR46 16A-79 Same as CR8 A3
CR47 16A-79 Same as CR8 A3
CR48 16A-79 Same as CR8 A3
CR49 1901-0378 Same as CR12 A3
CR50 1901-0378 Same as CR12 A3
CR51 1910-0016 Same as CR14 A3
CR52 1910-0016 Same as CRI4 A3
CR53 16A-45A Same as CR16 A3
CR54 1901-0378 Same as CR12 A3
CR55 1901-0377 Same as CR18 A3
CR56 16A-79 Same as CR8 A3
CR57 16A-79 Same as CR8 A3
CR58 16A-79 Same as CR8 A3
CR59 16A-79 Same as CR8 A3
CR60 1901-0378 Same as CR12 A3
CR61 1901-0378 Same as CR12 A3
CR62 1910-0016 Same as CR14 A3
CR63 1910-0016 Same as CR14 A3
CR64 16A-45A Same as CR16 A3
CR65 1901-0378 Same as CR12 A3
CR66 1901-0377 Same as CR18 A3
CR67 16A-79 Same as CR8 A3
CR68 16A-79 Same as CR8 A3
CR69 16A-79 Same as CR8 A3
CR70 16A-79 Same as CR8 A3
CR71 1901-0378 Same as CR12 A3
CR72 1901-0378 Same as CR12 A3
CR73 1910-0016 Same as CR14 A3
CR74 1910-0016 Same as CR14 A3
CR75 16A-45A Same as CR16 A3
CR76 1901-0378 Same as CR12 A3
CR77 1901-0377 Same as CR18 A3
CR78 16A-45A Diode A2
CR79 16A-45A Same as CR78 A2
CR80 16A-45A Same as CR78 A2
J1 10G16-IMX Connector, 16-pin A1
J2 10G2-22FX Mini-Jack A1
Q1A, 1B 1855-0031 Transistor, Field Effect A2
Q2 1854-0202 Transistor, 2N3390 A2
Q3 1854-0202 Same as Q2 A2
Q4 16T-81 Transistor, SM9143 A2
Q5 16T-81 Same as Q4 A2
Q6 16T-79 Transistor, 2N3391 A3
Q7 16T-50 Transistor, 2N1309 A3
Q8 16T-79 Same as Q6 A3
Q9 16T-50 Same as Q7 A3
Q10 16T-79 Same as Q6 A3
Q11 16T-50 Same as Q7 A3
-11
TM 11-6625-2872-14&P
Table 5-1. Reference Designation Index (Cont.)
Circuit Assembly
Reference Part Number Description Location
Q12 16T-78 Transistor, 2N3393 A2
Q13 16T-76 Transistor, 53-10 A2
Q14 16T-79 Same as Q6 A3
Q15 16T-50 Same as Q7 A3
Q16 16T-79 Same as Q6 A3
Q17 16T-50 Same as Q7 A3
Q18 16T-79 Same as Q6 A3
Q19 16T-50 Same as Q7 A3
Q20 5080-3724 Transistor, 54-23 A2
Q21 5080-3724 Same as Q20 A2
Q22 16T-76 Same as Q13 A2
Q23 16T-76 Same as Q13 A2
Q24 16T-78 Same as Q12 A2
Q25 16T-78 Same as Q12 A2
Q26 16T-81 Same as Q4 A2
Q27 16T-61 Transistor, 2N3053 A2
Q28 16T-61 Same as Q27 A2
Q29 16T-61 Same as Q27 A2
R1 50AB-155J Resistor, 1.5 Meg ±5% A4
R2 50AB-335J Resistor, 3.3 Meg ±5% A4
R3 0698-4981 Resistor, 32.4K 1%o A2
R4 50E-124F Resistor, 120K 1% A2
R5 50E-825-3F Resistor, 825K 1'% A4
R6 50E-976-3F Resistor, 976K 1% A2
R7 50E-205F Resistor, 2 Meg 1% A2
R8 50AB-472J Resistor, 4.7K 5% A2
R9 50E-503F Resistor, 50K 1% A2
R10 56PA-17 Potentiometer, 250 Ohm A2
R11 50E-403F Resistor, 40K 1% A2
R12 50E-503F Same as R9 A2
R13 50AB-472J Same as R8 A2
R14 0757-0309 Resistor, 61.9K 1% A2
R15 50E-104F Resistor, I00K% A2
R16 50E-104F Same as R15 A2
R17 50E-204F Resistor, 200K 1% A2
R18 50AB-472J Same as R8 A2
R19 50AB-222J Resistor, 2.2K 5% A2
R20 50AB-471J Resistor, 470 Ohm 5% A2
R21 50E-316-2F Resistor, 31.6K 1% A2
R22 50AB-331J Resistor, 330 Ohm 5% A2
R23 50AB--221J Resistor, 220 Ohm 5% A2
R24 50E-101F Resistor, 100 Ohm 1% A2
R25 50AB-223J Resistor, 22K ±5% A3
R26 50AB-472.J Resistor. 4.7K ±5% A3
R27 50E-133-2F Resistor, 13.3K ±1% A3
R28 50E-202F Resistor, 2K ±1% A3
R29 50AB-472J Same as R26 A3
R30 50AB-332J Resistor, 3.3K ±5% A3
R31 50E-153F Resistor, 15K ±1% A3
R32 50E-153F Same as R31 A3
R33 50E-104F Resistor, 100K ±1% A3
R34 50E-104F Same as R33 A3
R35 50AB-152J Resistor, 1. 5K 5% A2
R36 50E-504F Resistor, 500K ±1% A3
R37 50E-353F Resistor, 35K ±1% A3
-12-
TM 11-6625-2872-14&P
Table 5-1. Reference Designation Index (Cont.)
Circuit Assembly
Reference Part Number Description Location
R38 50E-105F Resistor, 1 Meg ±1% A3
R39 50E-105F Same as R38 A3
R40 50AB-223J Sane as R25 A3
R41 50AB-472J Same as R26 A3
R42 50E-133-2F Same as R27 A3
R43 50E-202F Same as R28 A3
R44 50AB-472J Same as R26 A3
R45 50AB-332J Same as R30 A3
R46 50E-153F Same as R31 A3
R47 50E-153F Same as R31 A3
R48 50E-104F Same as R33 A3
R49 50E-104F Same as R33 A3
R50 50E-504F Same as R36 A3
R51 50E-353F Same as R37 A3
R52 50E-105F Same as R38 A3
R53 50E-105F Same as R38 A3
R54 50AB-223J Same as R25 A3
R55 50AB-472J Same as R26 A3
R56 50E-133-2F Same as R27 A3
R57 50E-202F Same as R28 A3
R58 50AB-472J Same as R26 A3
R59 50AB-332J Same as R30 A3
R60 50E-153F Same as R31 A3
R61 50E-153F Same as R31 A3
R62 50E-104F Same as R33 A3
R63 50E-104F Same as R33 A3
R64 50E-105F Same as R38 A3
R65 50E-104F Same as R33 A3
R66 50E-105F Same as R38 A3
R67 50E-105F Same as R38 A3
R68 50E-185F Resistor, 1.8 Meg 1% A2
R69 50E-204F Same as R17 A2
R70 50AB-224J Resistor, 220K 5% A2
R71 50E-153F Same as R31 A3
R72 50E-153F Same as R31 A3
R73 50E-104F Same as R33 A3
R74 50E-104F Same as R33 A3
R75 50E-504F Same as R36 A3
R76 50E-204F Resistor, 200K ±1% A3
R77 50E-105F Same as R38 A3
R78 50E-105F Same as R38 A3
R79 50AB-223J Same as R25 A3
R80 50AB-472J Same as R26 A3
R81 50E-133-2F Same as R27 A3
R82 50E-202F Same as R28 A3
R83 50AB-472J Same as R26 A3
R84 50AB-332J Same as R30 A3
R85 50E-153F Same as R31 A3
R86 50E-153F Same as R31 A3
R87 50E-104F Same as R33 A3
R88 50E-104F Same as R33 A3
R89 50E-504F Same as R36 A3
R90 50E-353F Same as R37 A3
R91 50E-105F Same as R38 A3
R92 50E-105F Same as R38 A3
R93 50AB-223J Same as R25 A3
R94 50AB-472J Same as R26 A3
-13-
TM 11-6625-2872-14&P
Table 5-1. Reference Designation Index (Cont.)
Circuit Assembly
Reference Part Number Description Location
R95 50E-133-2F Same as R27 A3
R96 50E-202F Same as R28 A3
R97 50AB-472J Same as R26 A3
R98 50AB-332J Same as R30 A3
R99 50E-153F Same as R31 A3
R100 50E-153F Same as R31 A3
R101 50E-104F Same as R33 A3
R102 50E-104F Same as R33 A3
R103 50E-504F Same as R36 A3
R104 50E-353F Same as R37 A3
R105 50E-105F Same as R38 A3
R106 50E-105F Same as R38 A3
R107 50AB-223J Same as R25 A3
R108 50AB-472J Same as R26 A3
R109 50E-103F Resistor, 10K 1% A3
R110 50E-202F Same as R28 A3
R111 50AB-472J Same as R26 A3
R112 56PA-47 Potentiometer, 10K A3
R113 50AB-332J Same as R30 A3
R114 50E-153F Same as R31 A3
R115 50E-153F Same as R31 A3
R116 50E-104F Same as R33 A3
R117 50E-104F Same as R33 A3
R118 50E-504F Same as R36 A3
R119 50E-353F Same as R37 A3
R120 50E-105F Same as R38 A3
R121 50E-105F Same as R38 A3
R122 50AB-221J Same as R23 A2
R123 50AB-123J Resistor, 12K 5% A2
R124 5OAB-474J Resistor, 470K 5% A2
R125 50AB-474J Same as R124 A2
R126 50AB-123J Same as R123 A2
R127 50E-103F Resistor, 10K l% A2
R128 50AB-682J Resistor, 6.8K 5% A2
R129 56PA-47 Potentiometer, 10K A2
R130 50E-503F Same as R9 A2
R131 50E-503F Same as R9 A2
R132 50E-1O1F Same as R24 A2
R133 50E-158-OF Resistor, 158 Ohm 1% A2
R134 56PA-17 Same as R10 A2
R135 56PA-37 Potentiometer, 2. 5K A2
R136 50E-202F Resistor, 2K 1% A2
R137 0757-1011 Resistor, 18K 1% A2
R138 50E-50OF Resistor, 50 Ohm 1% A4
R139 50E-252F Resistor, 2. 5K 1% A2
R140 50E-50OF Same as R138 A4
R141 50E-50OF Same as R138 A4
R142 50E-50OF Same as R138 A4
R143 50E-500F Same as R138 A4
R144 0811-1797 Resistor, 50K 3% A2
R145 56S-8 Potentiometer, 1000 Ohm (SPAN BAL) A1
R146 50E-254F Resistor, 250K 1% A2
R147 50AB-153J Resistor, 15K 5% A2
R148 50AB-153J Same as R147 A2
R149 50E-254F Same as R146 A2
R150 50E-253F Resistor, 25K 1% A2
R151 50AB-124J Resistor, 120K 5% A2
-14-
TM 11-6625-2872-14&P
Table 5-1. Reference Designation Index Cont.
Circuit Assembly
Reference Part Number Description Location
R152 50E-253F Same as R150 A2
R153 50AB-103J Resistor, 10K 5% A2
R154 50AB-392J Resistor, 3.9K 5% A2
R155 0811-1797 Same as R144 A2
R156 50E-303F Resistor, 30K 1% A2
R157 50AB-123J Same as R123 A2
R158 50E-303F Same as R156 A2
R159 0811-1797 Same as R144 A2
R160 0811-1797 Same as R144 A2
R161 50E-104-2F Resistor, 10.4K 1% A2
R162 50E-752F Resistor, 7.5K 1% A2
R163 50E-503F Same as R9 A2
R164 50E-103F Same as R127 A2
R165 50E-103F Same as R127 A2
R166 56S-35 Potentiometer, 250K (GAIN) A1
R167 50E-253F Same as R150 A2
R168 50E-103F Same as R127 A2
R169 50E-103F Same as R127 A2
R170 50E-316-2F Same as R21 A2
R171 50AB-472J Same as R8 A2
R172 50AB-123J Same as R123 A2
R173 50AB-272J Resistor, 2.7K 5% A2
R174 50AB-121J Resistor, 120 Ohm 5% A2
R175 50E-403F Same as R11 A2
R176 56E-7 Potentiometer, 50K (LOG ZERO) A1
R177 50E-403F Same as R11 A2
R178 50AB-1OOJ Resistor, 10 Ohm s5% A3
R179 50AB-1OOJ Same as R178 A3
R180 50E-154F Resistor, 150K 1% A2
R181 50AB-562J Resistor, 5.6K 5% A2
S1 62B-219 Switch, Rotary A1
S2 62B-220 Switch, Wafer 3-Section, 9-Position A4
S3 62D-48 Switch, Toggle DPDT A1
T1 56T-11 Thermister, 20K A2
ACCESSORY
10G2-22MW Phone Plug A1
-15-
TM 11-6625-2872-14&P
Table 5-1. Reference Designation Index (Cont.)
Assembly
Quantity Part Number Description Location
MISCELLANEOUS
20370-0077 Knob A1
1652-65 Nameplate (08808-00020) A1
1816-64 Plate, Connector A1
1833-5 P1 Stand-Off A1
1833-6 P1 Nut A1
1860-3002 Chassis, Upper A1
1 860-3003 Chassis, Lower A1
2860-4005 Plate, Side A1
108800-20010 Handle A1
108808-00010 Panel, Front A1
108808-00050 Bracket, Printed Circuit Board A1
1752-427 Printed Board A2
101260-20501 Heat Sink, Bottom A2
101260-20601 Heat Sink, Top A2
1752-428 Printed Board A3
SHAFT LOCK (1/8 SHAFT)_817-C1
1817-5 Bushing, Shaft Lock
1817-2 Knob, Shaft Lock
17-7 Washer, Shaft Lock (Lower)
1817-6 Washer, Shaft-Lock (Upper)
1817-1 Nut, Shaft-Lock
181D-4-3/2Z 3/32 x 4-40 Allen Head Set Screw
181D-4-2Z 1/8" x 4-40 Allen Head Set Screw
SHAFT LOCK (1/4" SHAFT) 817-C2
1817-4 Bushing, Shaft-Lock
1817-3 Knob, Shaft-Lock
1817-7 Washer, Shaft-Lock (Lower)
1817-6 Washer, Shaft-Lock (Upper)
1817-1 Nut, Shaft-Lock
181D-4-3/2Z 3/32 x 4-40 Allen Head Set Screw
181D-4-2Z 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 NATIONAL PART NATIONAL
NUMBER FSCM STOCK NO. NUMBER FSCM STOCK NO.
0180-0022 28480 5910-00-538-3597
0180-0195 28480 5910-00-444-6642
0180-0374 28480 5910-00-931-7050
0370-0077 28480 5355-00-767-9444
0370-1107 28480 5355-01-011-4975
0698-3420 28480 5905-00-931-4067
0757-0309 28480 5905-00-632-5238
0757-0837 28480 5905-00-850-2180
0757-0843 28480 5905-00-830-6751
1910-0016 28480 5961-00-954-9182
5080-3724 28480 5961-00-105-4694
8808A 28480 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 Operator's, Organizational, Direct Support, General Support and Depot Maintenance
Manual: Signal Generator AN/URM-127 (NSN 6625-00-783-5965).
TM 11-6625-2658-14 Operator's, Organizational, Direct Support, and General Support Maintenance Manual
for Oscilloscope AN/USM-281C (NSN 6625-00-106-9622).
TM 38-750 The Army Maintenance Management System (TAMMS)
A-1
TM 11-6625-2872-14&P
TM 740-90-1 Administrative Storage of Equipment.
TM 750-244-2 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 COFH D EQPT REMARKS
00 PLUG-IN AMPLIFIER AM-6681(V)1/U Inspect 0.5 Visual
only
Service 0.5 6
Adjust 0.5 1,2,3
Test 1.0 1 thru 4
Repair 1.0 5
Overhaul 2.0 5
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
EQUIPMENT CATEGORY NOMENCLATURE STOCK NUMBER TOOL NUMBER
REF CODE
1H,D VOLTMETER, ELECTRONIC ME-202 6625-00-972-4046
2H,D OSCILLOSCOPE AN/USM-281C 6625-00-106-9622
3H,D GENERATOR. SIGNAL AN/URM-127 6625-00-783-5965
4H,D MULTIMETER AN/USM-223 6625-00-999-7465
5H,D TOOL KIT, ELECTRONIC EQUIPMENT TK-100/G 5180-00-605-0079
6 0 TOOL AND TEST EQUIPMENT AVAILABLE TO THE
ORGANIZATIONAL REPAIRPERSON BECAUSE OF
ASSIGNED MISSION.
*U.S GOVERNMENT PRINTING OFFICE: 1981-703-029/1060
D-4
FO 5-1. Model 8808A Log Level Schematic
By Order of the Secretary of the Army:
E. C. MEYER
General, United States Army
Official: Chief of Staff
J. C. PENNINGTON
Major General, United States Army
The Adjutant General
Distribution:
To be distributed in accordance with special mailing list.
PIN: 048121

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