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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
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5 SAFETY STEPS TO FOLLOW IF SOMEONE IS THE VICTIM OF ELECTRICAL SHOCK 1 DO NOT TRY TO PULL OR GRAB THE INDIVIDUAL IF POSSIBLE, TURN OFF THE ELECTRICAL POWER 2 IF YOU CANNOT TURN OFF THE ELECTRICAL POWER, PULL, PUSH, OR LIFT THE 3 PERSON TO SAFETY USING A DRY WOODEN POLE OR A DRY ROPE OR SOME OTHER INSULATING MATERIAL SEND FOR HELP AS SOON AS POSSIBLE 4 AFTER THE INJURED PERSON IS FREE OF CONTACT WITH THE SOURCE OF ELECTRICAL SHOCK, MOVE THE PERSON A SHORT DISTANCE AWAY AND 5 IMMEDIATELY START AR
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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
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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)...
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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 Amplif
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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 Schema
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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
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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 aco
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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 v
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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 opera
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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 syst
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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
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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
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TM 11-6625-2872-14&P Figure 4-1. 8808A Successive Detector Stages Figure 4-2. 8808A Block Diagram -7-
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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
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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 Ca
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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
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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
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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 S
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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 a
