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

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.  
i
TM 11-6625-2872-14&P  
TABLE OF CONTENTS  
Paragraph  
Page  
SECTION  
INTRODUCTION  
Scope......................................................................................................  
Indexes of Publications . . . . ...............................................................  
Maintenance Forms, Records, and  
Reports .............................................................................................  
Reporting Equipment Improvement  
Recommendations (EIR)..........................................................................  
Administrative Storage ............................................................................  
Destruction of Army Electronics  
Materiel.............................................................................................  
GENERAL INFORMATION  
Description ..............................................................................................  
INSTALLATION  
Portable Case or Rack Mounting .............................................................  
Installation in Sanborn Recording  
Systems ............................................................................................  
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................................................................................  
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................................................................................  
ii  
 
TM 11-6625-2872-14&P  
TABLE OF CONTENTS - Continued  
Page  
B.  
REFERENCES....................................................................................................  
COMPONENTS OF END ITEM LIST (COEIL)  
(Not applicable)  
C.  
BASIC ISSUE ITEMS LIST (BIIL)  
(Not applicable)  
MAINTENANCE ALLOCATION  
Section  
Introduction..........................................................................................................  
Maintenance Allocation Chart for Plug-In  
Amplifier AM-6681(V)1/U ..............................................................................  
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  
Page  
8808A Log Level Preamplifier ....................................................................................................  
8808A Successive Detector ......................................................................................................  
8808A Block Diagram ................................................................................................................  
Model 8808A Log Level Schematic ............................................................................................ In back  
of manual  
LIST OF TABLES  
Number  
Page  
Specifications ............................................................................................................................  
Bottom and Full Scale Signal Levels..........................................................................................  
Reference Designation Index .....................................................................................................  
Part Number - National Stock Number  
Cross Reference Index ........................................................................................................  
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  
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  
50 DB SPAN  
Range  
Switch  
Setting  
Bottom Scale  
Volts rms  
Full Scale  
Volts rms  
dBV  
0
dBV  
0
-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  
0
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.  
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.  
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,  
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  
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.  
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.  
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, 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  
A1  
A2  
A3  
08808-60020  
08808-60030  
08808-60050  
A4  
ACCESSORY  
MISCELLANEOUS  
C1  
C2  
C3  
C4  
C5  
C6  
C7  
C8  
8PA-6  
8PA-6  
Capacitor, 100 pF  
Same, as C1  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A2  
A2  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
0121-0163  
0160-2388  
8PA-35  
0160-2386  
0121-0160  
0160-2384  
0121-0160  
0160-2383  
8C-61  
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  
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  
C9  
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  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A3  
A3  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
Part Number  
Description  
5080-3722  
5080-3723  
5080-3722  
5080-3723  
8B-68  
8B-68  
8B-68  
8B-213  
0180-1862  
0180-1862  
0180-1862  
0180-1862  
8B-181  
8E-28  
8E-28  
8E-21  
16A-79  
16A-79  
16A-79  
16A-79  
16A-79  
16A-83  
16A-83  
16A-79  
16A-79  
Capacitor, 27 MFD 10V  
Capacitor, .22 MFD  
Same as C45  
Same as C46  
Capacitor, .01 MFD  
Same as C49  
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  
Same as CR1  
Same as CR1  
Same as CR1  
Diode (3 Pellet)  
Same as CR6  
Diode  
Same as CR8  
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  
16A-79  
Same as CR8  
1901-0378  
1901-0378  
1910-0016  
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  
16A-79  
16A-79  
Same as CRR  
Same as CR8  
Same as CR8  
1901-0378  
1901-0378  
1910-0016  
1910-0016  
16A-45A  
1901-0378  
1901-0377  
16A-79  
16A-79  
16A-79  
16A-79  
1901-0378  
1901-0378  
16A-45A  
16A-45A  
16A-45A  
1901-0378  
Same as CR12  
Same as CR12  
Same as CR14  
Same as CR14  
Same as CR16  
Same as CR12  
Same as CR18  
Same as CR8  
Same as CR8  
Same as CR8  
Same as CR8  
Same as CR12  
Same as CR12  
Same as CR16  
Same as CR16  
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  
J1  
Assembly  
Location  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A2  
A2  
A2  
A1  
A1  
A2  
A2  
A2  
A2  
A2  
A3  
A3  
A3  
A3  
A3  
A3  
Part Number  
Description  
1901-0377  
1910-0016  
1910-0016  
16A-45A  
1901-0378  
16A-79  
16A-79  
16A-79  
16A-79  
1901-0378  
1901-0378  
1910-0016  
1910-0016  
16A-45A  
1901-0378  
1901-0377  
16A-79  
Same as CR18  
Same as CR14  
Same as CR14  
Same as CR16  
Same as CR12  
Same as CR8  
Same as CR8  
Same as CR8  
Same as CR8  
Same as CR12  
Same as CR12  
Same as CR14  
Same as CRI4  
Same as CR16  
Same as CR12  
Same as CR18  
Same as CR8  
Same as CR8  
Same as CR8  
Same as CR8  
Same as CR12  
Same as CR12  
Same as CR14  
Same as CR14  
Same as CR16  
Same as CR12  
Same as CR18  
Same as CR8  
Same as CR8  
Same as CR8  
Same as CR8  
Same as CR12  
Same as CR12  
Same as CR14  
Same as CR14  
Same as CR16  
Same as CR12  
Same as CR18  
Diode  
16A-79  
16A-79  
16A-79  
1901-0378  
1901-0378  
1910-0016  
1910-0016  
16A-45A  
1901-0378  
1901-0377  
16A-79  
16A-79  
16A-79  
16A-79  
1901-0378  
1901-0378  
1910-0016  
1910-0016  
16A-45A  
1901-0378  
1901-0377  
16A-45A  
16A-45A  
16A-45A  
10G16-IMX  
10G2-22FX  
1855-0031  
1854-0202  
1854-0202  
16T-81  
16T-81  
16T-79  
16T-50  
16T-79  
16T-50  
16T-79  
16T-50  
Same as CR78  
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  
J2  
Q1A, 1B  
Q2  
Q3  
Q4  
Q5  
Q6  
Q7  
Q8  
Q9  
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  
R1  
Assembly  
Location  
A2  
A2  
A3  
A3  
A3  
A3  
A3  
A3  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A4  
A4  
A2  
A2  
A4  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A2  
A3  
A3  
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 Q13  
Same as Q12  
Same as Q12  
Same as Q4  
Transistor, 2N3053  
Same as Q27  
16T-50  
5080-3724  
5080-3724  
16T-76  
16T-76  
16T-78  
16T-78  
16T-81  
16T-61  
16T-61  
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-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-153F  
50E-104F  
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  
R2  
R3  
R4  
R5  
R6  
R7  
R8  
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  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A2  
A2  
A2  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
Part Number  
Description  
50E-105F  
50E-105F  
50AB-223J  
50AB-472J  
50E-133-2F  
50E-202F  
50AB-472J  
50AB-332J  
50E-153F  
50E-153F  
50E-104F  
50E-104F  
50E-504F  
50E-353F  
50E-105F  
50E-105F  
50AB-223J  
50AB-472J  
50E-133-2F  
50E-202F  
50AB-472J  
50AB-332J  
50E-153F  
50E-153F  
50E-104F  
50E-104F  
50E-105F  
50E-104F  
50E-105F  
50E-105F  
50E-185F  
50E-204F  
50AB-224J  
50E-153F  
50E-153F  
50E-104F  
50E-104F  
50E-504F  
50E-204F  
50E-105F  
50E-105F  
50AB-223J  
50AB-472J  
50E-133-2F  
50E-202F  
50AB-472J  
50AB-332J  
50E-153F  
50E-153F  
50E-104F  
50E-104F  
50E-504F  
50E-353F  
50E-105F  
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 R31  
Same as R33  
Same as R33  
Same as R36  
Same as R37  
Same as R38  
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 R31  
Same as R33  
Same as R33  
Same as R38  
Same as R33  
Same as R38  
Same as R38  
Resistor, 1.8 Meg 1%  
Same as R17  
Resistor, 220K 5%  
Same as R31  
Same as R31  
Same as R33  
Same as R33  
Same as R36  
Resistor, 200K ±1%  
Same as R38  
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 R31  
Same as R33  
Same as R33  
Same as R36  
Same as R37  
Same as R38  
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  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A3  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A4  
A2  
A4  
A4  
A4  
A4  
A2  
A1  
A2  
A2  
A2  
A2  
A2  
A2  
Part Number  
Description  
Same as R27  
Same as R28  
Same as R26  
Same as R30  
Same as R31  
Same as R31  
Same as R33  
Same as R33  
Same as R36  
Same as R37  
Same as R38  
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 R31  
Same as R33  
Same as R33  
Same as R36  
Same as R37  
50E-133-2F  
50E-202F  
50AB-472J  
50AB-332J  
50E-153F  
50E-153F  
50E-104F  
50E-104F  
50E-504F  
50E-353F  
50E-105F  
50E-105F  
50AB-223J  
50AB-472J  
50E-103F  
50E-202F  
50AB-472J  
56PA-47  
50AB-332J  
50E-153F  
50E-153F  
50E-104F  
50E-104F  
50E-504F  
50E-353F  
50E-105F  
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 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 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  
Same as R138  
Same as R138  
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-503F  
50E-1O1F  
50E-158-OF  
56PA-17  
56PA-37  
50E-202F  
0757-1011  
50E-50OF  
50E-252F  
50E-50OF  
50E-50OF  
50E-50OF  
50E-500F  
0811-1797  
56S-8  
50E-254F  
50AB-153J  
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  
A2  
Part Number  
Description  
Same as R150  
50E-253F  
50AB-103J  
50AB-392J  
0811-1797  
50E-303F  
50AB-123J  
50E-303F  
0811-1797  
0811-1797  
50E-104-2F  
50E-752F  
50E-503F  
50E-103F  
50E-103F  
56S-35  
50E-253F  
50E-103F  
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  
Same as R144  
Resistor, 10.4K 1%  
Resistor, 7.5K 1%  
Same as R9  
Same as R127  
Same as R127  
Potentiometer, 250K (GAIN)  
Same as R150  
Same as R127  
Same as R127  
Same as R21  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A1  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A2  
A1  
A2  
A3  
A3  
A2  
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  
50AB-1OOJ  
50E-154F  
50AB-562J  
A2  
S1  
S2  
S3  
62B-219  
62B-220  
62D-48  
Switch, Rotary  
Switch, Wafer 3-Section, 9-Position  
Switch, Toggle DPDT  
A1  
A4  
A1  
T1  
56T-11  
Thermister, 20K  
A2  
A1  
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  
2
1
1
1
1
1
1
2
1
1
1
1
1
1
1
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  
A1  
A1  
A1  
A1  
A1  
A1  
A1  
A1  
A1  
A1  
A1  
A2  
A2  
A2  
A3  
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  
1
1
1
1
1
1
1
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  
1
1
1
1
1
1
1
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  
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  
28480  
28480  
28480  
28480  
28480  
28480  
28480  
28480  
28480  
28480  
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  
-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.  
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  
C
O
F
H
D
EQPT REMARKS  
00  
PLUG-IN AMPLIFIER AM-6681(V)1/U  
Inspect  
0.5  
Visual  
only  
Service  
Adjust  
Test  
0.5  
6
0.5  
1.0  
1.0  
1,2,3  
1 thru 4  
Repair  
Overhaul  
5
5
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  
CATEGORY  
NOMENCLATURE  
1
2
3
4
5
6
H,D  
H,D  
H,D  
H,D  
H,D  
0
VOLTMETER, ELECTRONIC ME-202  
OSCILLOSCOPE AN/USM-281C  
6625-00-972-4046  
6625-00-106-9622  
6625-00-783-5965  
6625-00-999-7465  
5180-00-605-0079  
GENERATOR. SIGNAL AN/URM-127  
MULTIMETER AN/USM-223  
TOOL KIT, ELECTRONIC EQUIPMENT TK-100/G  
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  
Chief of Staff  
Official:  
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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