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
5 SAFETY STEPS TO FOLLOW IF SOMEONE IS THE VICTIM OF ELECTRICAL SHOCK 1 DO NOT TRY TO PULL OR GRAB THE INDIVIDUAL 2 IF POSSIBLE, TURN OFF THE ELECTRICAL POWER 3 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 4 SEND FOR HELP AS SOON AS POSSIBLE 5 AFTER THE INJURED PERSON IS FREE OF CONTACT WITH THE SOURCE OF ELECTRICAL SHOCK, MOVE THE PERSON A SHORT DISTANCE AWAY AND IMMEDIATELY START ART
This manual contains copyright material reproduced by permission of the Hewlett-Packard Company. TM 11-6625-2872-14&P TEHNICAL MANUAL No.
TM 11-6625-2872-14&P TABLE OF CONTENTS SECTION 0. I. II. III. IV. V. Paragraph Page 0-1 0-2 0-1 0-1 0-3 0-1 0-4 0-5 0-1 0-1 0-6 0-1 1-1 1 2-1 3 2-5 3 3-1 3-9 3-11 3-12 3-14 3-17 3-21 3-25 3 4 4 4 4 5 5 5 3-27 5 PRINCIPLES OF OPERATION Output ..................................................................................................... Stage Description .................................................................................... Signal Flow..........................
TM 11-6625-2872-14&P TABLE OF CONTENTS - Continued Page APPENDIX Section A. REFERENCES .................................................................................................... B. COMPONENTS OF END ITEM LIST (COEIL) (Not applicable) C. BASIC ISSUE ITEMS LIST (BIIL) (Not applicable) D. MAINTENANCE ALLOCATION A-1 I. Introduction.......................................................................................................... D-1 II.
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 ................................................................................................................
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.
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.
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.
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.
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.
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 +50 dB +10 dBV = Full scale input signal = 3.16 volts rms EXAMPLE 2: Minimum expected signal level .5 volt rms.
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.
TM 11-6625-2872-14&P Figure 4-1. 8808A Successive Detector Stages Figure 4-2.
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.
TM 11-6625-2872-14&P Table 5-1. Circuit Reference END ITEM C1 C2 C3 C4 C5 C6 C7 C8 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 Reference Designation Index Part Number Description 8808A 08808-60020 08808-60030 08808-60050 LOG LEVEL PREAMPLIFIER PRINTED CIRCUIT BOARD ASSY. PRINTEID CIRCUIT BOARD ASSY.
TM 11-6625-2872-14&P Table 5-1.
TM 11-6625-2872-14&P Table 5-1.
TM 11-6625-2872-14&P Table 5-1.
TM 11-6625-2872-14&P Table 5-1.
TM 11-6625-2872-14&P Table 5-1.
TM 11-6625-2872-14&P Table 5-1. Reference Designation Index Cont.
TM 11-6625-2872-14&P Table 5-1. Quantity Part Number Reference Designation Index (Cont.
TM 11-6625-2872-14&P Table 5-2. PART NUMBER - NATIONAL STOCK NUMBER CROSS REFERENCE INDEX PART NUMBER FSCM NATIONAL STOCK NO.
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.
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).
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.
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.
TM 11-6625-2872-14&P SECTION II. MAINTENANCE ALLOCATION CHART FOR PLUG-IN AMPLIFIER AM-6681(V)1/U (1) (2) GROUP NUMBER COMPONENT/ASSEMBLY 00 PLUG-IN AMPLIFIER AM-6681(V)1/U (3) (5) (6) TOOLS MAINTENANCE MAINTENANCE CATEGORY AND FUNCTION C O F H D EQPT REMARKS Inspect Service (4) 0.5 Visual only 0.5 6 Adjust 0.5 1,2,3 Test 1.0 1 thru 4 Repair 1.0 5 Overhaul D-3 2.
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 EQUIPMENT CATEGORY REF CODE NOMENCLATURE NATIONAL/NATO STOCK NUMBER TOOL NUMBER 1 H,D VOLTMETER, ELECTRONIC ME-202 6625-00-972-4046 2 H,D OSCILLOSCOPE AN/USM-281C 6625-00-106-9622 3 H,D GENERATOR.
FO 5-1.
By Order of the Secretary of the Army: Official: J. C. PENNINGTON Major General, United States Army The Adjutant General Distribution: To be distributed in accordance with special mailing list. E. C.
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