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04935-90029 4935A Operating & Service Nov66


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                                         Errata


Title & Document Type: 4935A Operating & Service
                       Manual

Manual Part Number: 04935-90029


Revision Date: November 1966



HP References in this Manual

This manual may contain references to HP or Hewlett-Packard. Please note that Hewlett-
Packard's former test and measurement, semiconductor products and chemical analysis
businesses are now part of Agilent Technologies. We have made no changes to this
manual copy. The HP XXXX referred to in this document is now the Agilent XXXX.
For example, model number HP8648A is now model number Agilent 8648A.

About this Manual

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product. This manual provides the best information we could find. It may be incomplete
or contain dated information, and the scan quality may not be ideal. If we find a better
copy in the future, we will add it to the Agilent website.


Support for Your Product

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                                 www.tm.agilent.com

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                                  Operating and Service Manual




                              HP 4935A
                       Transmission Impairment
                            Measuring Set

                                                Serial Numbers

                       This manual applies to instruments with serial numbers prefixed:

                                                    :2846A




                  Copyright Hewlett-Packard Co./Colorado Telecommunications Division 1987
                   5070 Centennial Blvd., P.O. Box 7050, Colorado Springs, Colorado 80933

                                          ALL RIGHTS RESERVED


Manual Part No: 04935-90029                                                               Printed Nov. 1966
Microfiche Part No: 0493598804                                                             Printed in U.S.A.
Warnirlgs/(:autions                                                                                                                                     Model 4YXA




                                                                       [ WARNING        1




SAFETY                                                                           GROUNDING

If this instrument is to be energized via an autotransformer
                                                                                 Any       interruption     of    the     protective     (grounding)          conductor
for voltage reduction, make sure the common terminal is
                                                                                 (inside or        outside the instrument) or disconnecting the
connected to the earthed pole of the power source.
                                                                                 protective         earth terminal can make this instrument
                                                                                 dangerous.        Intentional interruption is prohibited.
BEFORE SWITCHING ON THIS INSTRUMENT, the
protective earth terrninals of this instrument must be
connected to the protective conductor of the (mains)
                                                                                 HIGH        VOLTAGE
power cord. The rnains plug shall only be inserted in a
socket outlet provided with a protective earth contact. The
p r o t e c t i v e actlon m u s t n o t b e n e g a t e d b y u s e o f a n     Any       adjustment,      maintenance,         and    repair     of   the     opened
extension     cord    (power    cable)    without    a    protective      con-   instrument under voltage should be avoided as much as
ductor      (grounding).                                                         possible and, when inevitable, should be carried out only by
                                                                                 a skilled person who is aware of the hazard involved.
Make sure that only fuses with the required rated current
and of the specified type (normal blow, time delay, etc.)                        Capacitors inside the instrument may still be charged even
are used for replacement. The use of repaired fuses and the                      if the instrument has been disconnected from its source of
short-circuiting of fuse holders must be avoided.                                SUPPlY.


Whenever      It is likely that the protection offered by fuses                  Adjustments        and      service      described     herein       are    performed
has been impaired,             the    instrument         must   be     made      with      power    supplied       to     the    instrument        while    protective
inoperative         and be secured against any unintended                        covers      are   removed.        Energy       available     at   many       points,   if
operation.                                                                       contacted, result in personal injury.




LINE      VOLTAGE                                                                BEFORE SWITCHING ON THIS INSTRUMENT, ensure
                                                                                 that the line power (mains) plug is connected to a
BEFORE        SWITCHING         ON    THIS       INSTRUMENT,           make      three-conductor          line    power      outlet    that    has      a     protective
sure     instrument    requirements      match    the     voltage    of   the    ( e a r t h ) g r o u n d . ( G r o u n d i n g o n e c o n d u c t o r o f a two-
power     source.                                                                conductor      outlet     is    not    sufficient.)


GROUNDING

BEFORE SWITCHING ON THIS INSTRUMENT, ensure
that all devices connected to this instrument are connected
to the protective (earth) ground.


ii
Model &%A                                                                                                                                                  IEC Symbols




                                                                        IEC SYMBOLS

The follownq IS rl 1151 of key I EC symbols used by Hewlett-Packard. All symbols             HZ           Hertz (IEC 1174. symbol       No. 365).
are normally applwd adlacent to the device requur~ng the symbol. They shall not
be placed on removable parts likely to be detached or lost.                                               Contactor, normally closed. In order to avold confusion with
                                                                                                          t h e s y m b o l f o r a capacitor. t h e deance b e t w e e n t h e
                                                                                                          horizontal (as drawn here) lines should be at least equal to
                    lnstrucf~on  Manual symbol: If necessary. to preserve the               z             the length of those lines (IEC 117-3, symbol No. 215.21.


      !
      A             apparatus from damage !t IS necessary for the user to refer to
                    the mstruct~on manual, then shall the apparatus be marked
                    wth thlssymbol (IEC 348;16a).
                                                                                     In addltlon the following describes the use of Warmngs.
                                                                                     in HP Automatic Test System Manuals.
                                                                                                                                                 Cautions and Notes used



                                                                                     Warnings, cautions and notes. (All) Warmngs and caut!ons shall precede the text
                    Termnal dewces fad from the ~ntertor by live voltages that
                                                                                     to which each apples but notes may precede or follow applicable text depending
                    may be dangerous when connecting to or dlsconnectlng   from

        1           those dewces shall be marked wth the flash shown when the
                    volrdge exceeds 1 KV: The flash shall be red (IEC 348;lEc).
                                                                                     on the material to be highllghted. Warnings, cautions, and notes shall not contan
                                                                                     procedural steps nor shall they be numbered. When a warmng, caution, or note
                                                                                     consists of two or more paragraphs, the heading WARNING, CAUTION, NOTE,
                                                                                     shall not be repeated above each paragraph. If it is ever necessary to precede a
                    Earth Termunals. If the use of this symbol for the protectwe

        -
        -           earth termmal 1s not permttted by National Standards, it may
                    be modlfled. for example, by bang placed irwde a circle (IEC
                    348.18a).
                                                                                     paragraph by both a warmng and a note, or a caution and a note, etc. they shall
                                                                                     appear m the sequence as noted, namely. warnings. cautions, notes. Such inserts
                                                                                     I" the text shall be short and concise and be used to emphasize important and
                                                                                     critical mstructtons.

                    AC current (IEC 117-l. symbol No. 3).

     ---            DC current fIEC 117-l. symbol No. 2).

                    AC or DC current (I EC 1 17-l. symbol No. 8).
                                                                                                   An operating procedure, practtce. etc. which. If not
                                                                                                   correctly followed, could result III personal injury or
                                                                                                   loss of life.
                    Frame or chaws connection. The hatchmg may be com-
                    pletely or partly omitted if there II no ambiguity. If the
                    hatching is omated, the line representing the frame or chassis
                    shall be thrcker (I EC 117.1, symbol No. 87).

         A          Ampere (IEC 1174, symbol No. 356).
                                                                                                  An operating procedure, practw, etc. which, if not
         V          Volt lltC 1174. symbol No. 357).                                              strictly observed, could result tn damage to, or
                                                                                                  destruction of, eqwpment.
        VA          Voltampere       (I EC 1174, symbol No. 358).
                                                                                                   NOTE: An operating procedure, condmon,           etc. whwzh
         w          Watt (I EC 1174, symbol No. 3601.                                              it is essential to hIghlIght.

        Wh          Watthour (I EC 1174, symbol No. 361).                            -health hazards precaution data. (All) When hazardous chemicals or adverse health
                                                                                     factors, in the environment or use of the equipment       cannot be eliminated,
        VAh         Voltamperehour       (IEC 1174, symbol No. 362).                 ,tppropriate precautionary requirements shall be mcluded.




                                                                                                                                                           iii/(iv    blank)
 Model 4935A                                                                                                                                     Table of Contents




                                                                 TABLE OF C:ONTENTS
 Section                         Title                                      Page         Section                                  Title                              Page


I. GENERAL INFORMATION                                                                    3-48.    Signal Frequency Interference .................... .3-24
                                                                                          3-52.    Impulse Noise.. .............................................. .3-24
    l-l.   Introduction.. ................................................... l - l       3-55.    Noise-to-Ground Measurement.. ................ .3-25
    l-3.   General Description.. ..................................... l - l              3-59.    Peak-to-Average Ratio Measurement.........3-2 5
    l-5.   Instrument Identification.. ............................. l-1
    l-7.   Specifications.. ................................................. l - l     IV.        PERFORMANCE                   TESTS
    l-9.   Safety Considerations.. .................................. .1-4
  1-12.    Related Manuals.. ........................................... l-4               4-l.    Introduction ................................................... .4-l
  1-14.    User Repair.. ................................................... l-4           4-3.    Equipment Required.. .................................. .4-l
  1-16.    Options and Accessories.. .............................. l-4                    4-5.    Test Record ................................................... .4-l
  1-19.    Warranty.. ...................................................... ..l- 4        4-7.    Self Check ...................................................... .4-l
  1-21.    Recommended Test Equipment.. ................. l-4                              4-9.    Performance Verification.. ........................... .4-l
  l-23.    Battery Operation (0pt.s 001 & 003) .......... l-6                             4-12.    Performance Tests.. ...................................... .4-2
  l-26.        Charging the Batteries.. ........................... l-6                   4-13.        Transmitter Flatness at + 10dBm.. ........ .4-2
  l-29.        Operating Temperature.. ......................... l-6                      4-14.        Transmitter Flatness a t -40dBm.. ...........4-4
                                                                                          4-15.        Receiver Accuracy at t 1ldBm
II.         INSTALLATION                                                                                & -4OdBm.. .............................................. .4-8
                                                                                          4-16.        Autorange Test.. ...................................... .4-10
   2-l.    Introduction.. .................................................. .2-l         4-17.        Filter Tests.. ............................................. .4-11
   2-3.    Initial Inspection.. .......................................... .2-l           4-18.        Impulse Noise DAC Test.. ..................... .4-14
   2-6.    Preparation for Use.. ..................................... .2-l               4-19.        Count Limit Test.. ................................... .4-16
   2-7.    Power Requirements.. ................................... .2-l                  4-20.        Termination Impedance Test.. .............. .4-17
   2-9.    Line Voltage Selection.. ................................. 2-l                 4-21.        Hold Tone Dropout Detector Test........4-19
  2-11.    Power Cable.. ................................................. .2-2           4-22.        Hold Circuit Test .................................... .4-20
  2-13.    Operating Environment.. .............................. .2-2                    4-23.        Distortion T e s t ........................................ .4-21
  2-16.    Storage a n d Shipment.. ................................. .2-2                4-24.        P/AR Test.. .............................................. .4-25
  2-17.        Environment.. ........................................... .2-2             4-25.        Noise-to-Ground(Std. dc Opt. 001)....... .4-26
  2-19.    Instrument Packaging ................................... .2-2
                                                                                        V.         ADJUSTMENTS/CALIBRATIONS
III.        OPERATION
                                                                                           5-l.    Introduction ................................................... .5-l
   3-l.      Introduction .................................................... .3-l        5-3.    Safety Considerations.. ................................. .5-l
   3-3.    Self Check ....................................................... .3-l         5-5.    Equipment Required.. .................................. .5-l
   3-5.     Error Messages.. ............................................ .3-l             5-6.        Instrument Access.. ................................. .5-l
   3-7.     Operating Instructions .................................. .3-6                 5-9.    Adjustment Locations.. ................................. .5-l
   3-9.      Measurements ................................................ .3-7           5-11.    Adjustments.. ................................................. .5-2
  3-10.     Measurement Principles ............................... .3-17                  5-13.    t 5V, + 14V, and -14V Power
  3-12.     Input-Output Switching ................................ .3-17                          Supply Adjustments ...................................... .5-3
  3-19.    Level and Frequency Measurements.. ........ .3-18                              5-14.        Output Level & Transmit
  3-21.     1000 H z Loss.. ................................................ .3-18                     Monitor Loop Adjustments.. ................. .5-4
  3-24.    Frequency Shift .............................................. .3-18           5-15.    Receiver Adjustments.. ................................. .5-5
  3-26.    Attenuation Distortion.. ................................ .3-18                5-17.    Notch Filter Adjustments.. ........................... .5-7
  3-30.    SF Skip ............................................................ .3-19     5-18.    Al3 P/AR Filter and Latch
  3-32.    Message Circuit Noise Measurements.. .... ..3-19                                        Adjustments(0pt.s 001 & 003). ................... .5-8
  3.40.    Noise Measurements ..................................... .3-22                 5-19.        Hold Circuit Adjustments.. .................... .5-9
  3-42.    Noise-with-Tone (Notched Noise) .............. .3-22
  3-45.    Signal-to Noise Measurement.. .................... .3-22




                                                                                                                                                                            V
 Table of Contents                                                                                                                                 Model 4935A




                                                          TABLE OF CONTENTS (cord)
 Section                          Title                                   Page      Section                                  Title                               Page


VI.           REPLACEABLE                 PARTS                                      8-80.       Input Select/Notch Filter/
                                                                                                 25 dB Amp.. ............................................. .8-17
      6-l. Introduction.. .................................................. .6-l    8-85.       Noise Filter Circuitry.. ............................ .8-17
      6-3. Replaceable Parts List.. ............................... ..6- 1           8-97.       Level Detectors ....................................... .8-19
      6-5. Ordering Information ................................... .6-l            8-100.       Impulse Noise Detectors.. ...................... .8-19
                                                                                    8-102.     Transmitter .................................................... .8-19
VII.          MANUAL            CHANGES                                             8-104.       T e s t Signal Generation Method.. .......... .8-20
                                                                                    811.3.       Circuit Description.. ................................ .8-21
      7-1. Introduction .................................................... .7-l   8-126.    Power Supply Theory.. .................................. .8-23
      7-3. Manual Changes.. .......................................... .7-l         8-128.       A C Line Supplies .................................... .8-23
      7-6. Manual Change Instructions......................... 7-l
                                                    .                               8-131.       Regulators.. .............................................. .8-24
                                                                                    8-139.    Charger Board Theory of Operation.. ........ .8-25
VIII.         SERVICE                                                               8-141.       Battery Charging.. ................................... .8-26
                                                                                    8-144.       Power Source Selection.. ........................ .8-26
   8-l. General Information .................................... ..8- 1             8-146.       Relay Drive Circuitry.. ............................ .8-26
   8-8. How Measurements are Made .................... .8-3                         8-148.       Inhibit Circuit ........................................... 8-26
  8-10.    Level a n d Frequency.. ............................. .8-4               8-153.     Maintenance .................................................. .8-28
  8-13.    Noise.. ......................................................... 8-4    8-1.55.      Periodic Maintenance.. ........................... .8-28
  8-16.     Noise-with-Tone ...................................... .8-4             8- 157.      Failure Maintenance.. ............................. .8-28
  8-19.     Signal-to-Noise.. ....................................... .8-5          8-159.        Component Replacement ...................... .8-28
  8-22.     Impulse Noise .......................................... .8-5           8-164.       Soldering .................................................. .8-28
  8-26.     Noise-to-Ground (Std & Opt. 001). ...... .8-6                           8-166 .       Cleaning.. .................................................. .8-28
  8-29.     Peak-to-Average Ratio: P/AR                                             8-168.    Disassembly .................................................... 8-29
            (0pt.s 002 & 003) .................................... .a-6             8-169.       Remove Case.. ......................................... .8-29
  8-32. Frequency Measurement.. ............................ .8-6                   8-171.    Receiver Board/Shield Plate/
  8-34. Level Measurement.. ..................................... .8-7                        Battery Charger Board Disassembly.. ........ .8-29
  8-38. How to Compute Frequency and Level                                          8-173.    Switchboard/Front Panel Removal.. .......... .8-30
        Measurement ................................................. .8-8          8-175.    Transmitter Board Removal.. ...................... .8-30
  8-39.     Level Calculation Example.. ................... .8-8                    8-177.    Reassembly.. .................................................. .8-31
  8-42. Control Theory of Operation.. ..................... .8-11                   8-179.    Power Supply Troubleshooting.. ................. .8-33
  8-44. Microprocessor t o Instrument.. ................... .8-11                   8-181.    Minimum Core Troubleshooting.. .............. .8-34
  8-45.     System Latches.. ....................................... .8-H           8-183.        Procedure .................................................. 8-35
  8-48. Instrument t o Microprocessor.. ................... .8-12                   8-186.        Display Troubleshooting.. ...................... .8-36
  8-51. Operator to Microprocessor ........................ .8-12                   8-189.    Control Troubleshooting.............................. .8-36
  8-52.     Keyboard Interrupt.. ................................ .8-12             8-190.        Troubleshoot Keyscan/
  8-54.     Receiver Impedance Switches.. .............. .8-12                                    Interrupt Circuitry.. ................................. .8-36
  8-57. Microprocessor t o Operator.. ...................... .8-13                  8-192.    Control and Counting Section
  8-58.     Displays.. ................................................... .8-13              Troubleshooting.. .......................................... .8-36
  8-60. Instrument t o Operator ................................ .8-13              8-194.    Transmitter Troubleshooting ...................... .8-37
  8-62.     Monitor Amp ........................................... .8-13           8-196.        Transmit Clock Generator.. ................... .8-37
  8-64.     Beep Generator ....................................... .8-13            8-200.        Transmitter Signature Analysis
  8-66. Operator t o Instrument ................................ .8-13                            Procedure.. ............................................... .8-37
  8-68. Miscellaneous Circuitry.. .............................. .8-13              8-202.        Digital-to-Analog Conversion ............... .8-39
  8-73. Receiver Theory of Operation.. ................... .8-15                    8-204.        Filter and Signal Select Circuitry.. ........ .8-40
  8-76.     I/O Switching/Hold Circuits/                                            8-207.        Output Amplifier.. ................................... .8-42
            Termination .............................................. .a-16        8-210.        Transmit Monitor.. .................................. .8-43
                                                                                    8-212.    Receiver Troubleshooting.. .......................... .8-43




 vi
Model 4935A                                                                                                                                     Table of Contents




                                                               TABLE OF CONTENTS
Section                        Title                                      Page        Section                                   Title                               Page


8-217.       Setup.. ........................................................ .8-44   8-259.        Relay Drive Circuitry,
8-219.       Overall Transmit Monitor T e s t ............. .8-44                                   Low Voltage Inhibit Circuitry.. ............. .8-53
8-222.       Transmit Monitor Signal ........................ .8-45                   8-261.        Inhibit Circuitry AC and
8-225.       Noise Filter.. ............................................. .8-45                     Low Voltage.. ........................................... .8-54
8-227.       Simplified Autorange Check.. ................ .8-46                      8-263.        Delay and Relay Drive Circuitry.. ......... .8-54
8-229.       Detector Select.. ....................................... .8-47          8-265.        AC and Low Voltage Inhibit
8-232.       Inputs from Front Panel/                                                               Troubleshooting ...................................... .8-55
             Notch Filter/ 25dB Amp/Tone                                              8-267.    Service Aids ................................................... .8-57
             Dropout Signal Path.. .............................. .8-47               8-268.    Service Selection of Input/
8-233.       Setup.. ........................................................ .8-48             Notch Filter/25dB Amp.. ............................. .8-57
8-235.       Input Transformer.. ................................. .8-48              8-270.        Procedure.. ............................................... .8-57
8-237.       Noise-to-Ground Input Path                                               8-272.    Service Selection of Noise Filters
              (Noise-to-Ground Units only) ............... .8-48                                b y Hand.. ........................................................ .8-58
8-239.       Tone Dropout Signal Path.. .................... .8-49                    8-274.        Procedure ................................................. .8-58
8-242.       Notch Filter .............................................. .8-49        8-276.    Service Selection of Autorange
8-246.    Noise Filters ................................................... .8-49               Gain for Service.. ........................................... .8-58
8-248.       Autorange ................................................. .8-49        8-278.        Procedure ................................................. .8-58
8-250.        Detector Troubleshooting.. .................... .8-50                   8-279.    Hand Selection of AX57 and A3C160
8-252.    Impulse Noise Circuitry.. .............................. .8-50                        (A3C57 and A3C160 for P/AR Units)
82.54.    Charger Board Troubleshooting ................. .8-52                                 for Desired Frequency Response.. .............. .8-59
8-255.        Procedure ................................................. .8-52       8-282.        Hand Selection of C57 and Cl60.......... .8-60
8-257.       Charge Circuitry/Charge                                                  8-283.    FiIters: Response of Each Stage.................. .8-60
              Inhibit Circuitry ....................................... .8-52




                                                                                                                                                                            vii
Table of Contents                                                                                                                                      Model 4935A




                                                           LIST OF ILLUSTRATIONS
Section                         Title                                    Page        Section                                    Title                               Page


    l-l. Model 4935A Transmission Impairment                                           5-1. Output Level and Transmit Monitor
          Measuring Set ................................................ .1-O               Loop Adjustments.. ....................................... .5-4
    l-2. Charge Acceptance at Various                                                  5-2. Receiver Adjustments.. ................................. .5-5
          Tempcraturcs.. ................................................ l-6          5-3. Hold Circuit Adjustments.. .......................... .5-9

   2-l. Lint Voltage Selection.. ................................ .2-l                6-l. Exploded View Case and Covers.. .............. .6-4
                                                                                      6-2. Exploded View Assemblies and Cables.. .. ..6- 5
  3-l. Front and Rear Panel Controls/                                                 6-3. Exploded View Battery Option.. ................. .6-7
          Connectors/indicators.. ................................ .3-2
  3 - 2 . Measurements ................................................ .3-6           7-l.    A2 Switch Board Component Locator.. .... ..7-10
  3-3. Input-Output Switching ................................. 3-17                   7-2.    A5 Charger Board Component Locator.. . ..7-14
  3-4. Level and Frequency Mcasurcments.. ........ .3-18                               7-3.    Partial A5 Charger Board Schematic.. ....... .7-14
  3-5. Message Circuit Noise Measurements ...... ..3-19                                7-4.    Al4 Transmitter Board Component
  3-6. C-Mcssagc Weighting Characteristic.. ........ .3-20                                     Locator ........................................................... .7-15
  3-7. 3 kHz Flat Weighting Characteristic.. ......... .3-20                           7-5.    Partial A4 and Al4 Schematic ...................... 7-16
  3-8. Program Weighted liltcr.. ............................. .3-21                   7-6.    Al4 P/AR Transmitter Board
  3-9. 15 kHz Flat Filter .......................................... .3-21                     Component Locator.. .................................... .7-16
 3-10. SOkBit Filter. ................................................... .3-22        7-7.    A4 Transmitter Board Component
 3-11. C-Message Weighting with Notch                                                           Locator ........................................................... .7-17
          Characteristic.. ............................................... .3-23       7-8.    Partial Power Supply Schematic.. ................ .7-18
 3-12. Signal-to-Noise Measurement ..................... .3-23                         7-9.    Al3 P/AR Receiver Board Component
 3-13. Impulse Noise Waveform                                                                  Locator ........................................................... .7-19
          Rcprcscntation.. ............................................. .3-24       7-10.     A3 Receiver Board Component
 3-14. Noise-to-Ground Related to Message                                                      Locator ........................................................... .7-20
          Circuit Noise .................................................. .3-2.5    7-11.     A3 Receiver Board Schematic
 3-15. P/AR Transmit Signal Frcqucncy                                                           (Sheet 1 of 2) ................................................. .7-21
          Spectrum.. ....................................................... .3-26   7-12.     A3 Receiver Board Schematic
 3-16. P/AR Transmit Signal Envelope.. ............... .3-26                                    (Sheet 2 of 2) ................................................. .7-23
                                                                                     7-13.     Al3 P/AR Receiver Board Component
  4-l. Transmitter Flatness Test                                                                Locator ........................................................... .7-25
        a t + 10 dBm .................................................... .4-2       7-14.     A3 Receiver Board Component
  4-2. Transmitter Flatness Test                                                                Locator ........................................................... .7-26
        a t -40 dBm ...................................................... .4-4      7-15.     A3 Receiver Board Schematic
  4-3. Reccivcr Test at + 11 dBm                                                                Diagram (Partial). ......................................... .7-27
        a n d -40 dBm ................................................... .4-8       7-16.     A4 Transmitter Board Component
  4-4. Autorangc Test .............................................. .4-10                      Locator ........................................................... .7-28
  4-5. Filter Tests.. .................................................... .4-11     7-17.     Al4 Transmitter Board Component
  4-6. Impulse Noise DAC T e s t ............................. .4-14                            Locator ........................................................... .7-28
  4-7. Count Limit Test ........................................... .4-16            7-18.     A4 Transmitter Board Schematic
  4-8. Termination Impedance Test....................... .4-17                                  Diagram ......................................................... .7-29
  4-9. Hold Tone Dropout Detector Test.. ........... .4-19                           7-19.     Al4 Transmitter Board Schematic
 4-10. Hold (Xrcuit `Test.. ......................................... .4-20                     Diagram (Partial). ......................................... .7-30
 4-11. Distortion Test ................................................ 4-21         7-20.     Al4 Transmitter Board Schematic
 4-12. -40 dBm Distortion Test.. ............................. .4-22                            Diagram (Partial). ......................................... .7-30
 4-13. Filter Circuits ................................................. .4-23       7-21.     A2 Switchboard Component Locator.. ....... .7-32
 4-14. P/AR Test.. .................................................... .4-25        7-22.     A2 Switchboard Schematic Diagram.. ........ .7-33
 4-15. Noise-to-Ground Test.. ................................. .4-26                7-23.     A3 Receiver Board Component



 .. .
VW
Model 4935A                                                                                                                                   Table of Contents




                                                           LIST OF ILLUSTRATIONS
Section                        Title                                    Page        Section                                    Title                              Page


       Locator.. .......................................................... .7-34   8-19.     P/AR Signal Frequency Spectrum ............. .8-41
 7-24. Al3 Receiver Board Component                                                 8-20.     P/AR Transmit Signal Envelope.. .............. .8-42
       Locator.. .......................................................... .7-35   8-21.     20 H z Waveform ........................................... .8-43
 7-25. Receiver Board Schematic                                                     8-22.     Transmit Monitor Test Output ................... .8-44
       Diagram (Sheet 1 of 2) ................................. .7-36               8-23.     4935A Signal Flow Block Diagram.. ........... .8-67
 7-26. Receiver Board Schematic                                                     8-24.     Al Front Panel Schematic Diagram.. .......... 8-69
       Diagram (Sheet 2 of 2) ................................. .7-37               8-25.     A2 Switchboard Component Locator.. ....... .8-70
 7-27. A4 Transmitter Board Component                                               8-26.     A2 Switchboard Schematic Diagram.. ........ .8-71
       Locator.. .......................................................... .7-38   8-27.     A3 Receiver Board Component
 7-28. Al4 Transmitter Board Component                                                        Locator ........................................................... .8-72
       Locator ............................................................ .7-39   8-28.     Al3 Receiver Board Component
 7-29. A4 Transmitter Board Schematic                                                         Locator ........................................................... .8-72
       Diagram (Sheet 1 of 2) ................................. .7-40               8-29.     A3 Receiver Board Schematic
 7-30. A4 Transmitter Board Schematic                                                         Diagram (Sheet 1 of 4)................................. .8-73
       Diagram (Sheet 2 of 2) ................................. .7-41               8-30.     A3 Receiver Board Schematic
 7-31. A5 Charger Board Component Locator......7-4 2                                          Diagram (Sheet 2 of 4). ................................ .8-75
 7-32. A5 Charger Board Schematic Diagram.......7-4 3                               8-31.     A3 Receiver Board Schematic
                                                                                              Diagram (Sheet 3 of 4). ................................ .8-77
  8-l. 4935A Main Block Diagram.. ....................... .8-l                      8-32.     A3 Receiver Board Schematic
  8-2. Voltage-to-Frequency Conversion                                                        Diagram (Sheet 4 of 4). ................................ .8-79
       Characteristics ................................................. 8-7        8-33.     A4 Transmitter Board Component
  8-3. Voltage-to-Frequency Conversion                                                        Locator ........................................................... .8-80
       output ............................................................. .8-8    8-34.     Al4 Transmitter Board Component
  8-4. Frequency and Level Measurement                                                        Locator ........................................................... .8-80
       Timing.. ........................................................... .8-9    8-35.     A4 Transmitter Board Schematic
  8-5. Control Circuitry Block Diagram.. .............. .8-11                                 Diagram (Sheet 1 of 5). ................................ .8-81
  8-6. Receiver Block Diagram.. ............................. .8-14                 8-36.     A4 Transmitter Board Schematic
  8-7. Switchboard Block Diagram ........................ .8-15                               Diagram (Sheet 2 of 5). ................................ .8-83
  8-8. Input-Output Switching ................................ .8-16                8-37.     A4 Transmitter Board Schematic
  8-9. Filter Block Diagram .................................... .8-17                        Diagram (Sheet 3 of 5). ................................ .8-85
 8-10. Autorange Block Diagram ........................... .8-18                    8-38.     A4 Transmitter Board Schematic
 8-11. Stair-Step Sinewave.. ..................................... .8-20                      Diagram (Sheet 4 of 5). ................................ .8-87
 8-12. Transmitter Block Diagram ......................... .8-21                    8-39.     A4 Transmitter Board Schematic
 8-13. Power Supply Block Diagram.. .................... .8-23                                Diagram (Sheet 5 of 5)................................. .8-89
 8-14. Charger Board Block Diagram.. .................. .8-25                       8-40.     A5 Charger Board Component Locator.. .. ,890
 8-17. Instrument Troubleshooting ........................ .8-32                    8-41.     A5 Charger Board Schematic Diagram.. .. ..8-9 1
 8-18. Stair-Step Sinewave.. ..................................... .8-39




                                                                                                                                                                          ix
Table of Contents                                                                                                                                         Model 4935A




                                                                               LIST OF TABLES
Table                              Title                                         Page        Table                                 Title                              Page


   l - l . Specificalions.. ................................................. l-2              7-l. Manual Changes............................................ .7-l
   l-2. Recommended T e s t Equipment.. ................. l-5
   l-3. List of Parts Used for Performance                                                    8-l.    Measurements Summary.. ............................ .8-3
           T e s t s ................................................................. l-5    8-2.    Noise Amplification.. ..................................... 8-5
                                                                                              8-3.    Reference Signatures.. .................................. .8-38
  2-l. H P Plug Styles.. ............................................... 2-3                  8-4.    Wideband Filter Response ........................... S-40
                                                                                              8-5.    5 kHz Low Pass Filter Response ................ .8-40
   4-1.    Transmitter Flatness a t + 10 dBm ............... .4-3                             8-6.    Output Select MUX.. .................................... .8-41
   4-2.    Transmitter Flatness a t -40 dBm.. ............... .4-5                            8-7.    Transmit Monitor Test.. ............................... .8-43
   4-3.    Abbreviated Transmitter Flatness.. ............. .4-7                              8-8.    A3UlB Voltages ........................................... .8-51
   4-4.    Receiver A c c u r a c y T e s t Table ..................... .4-9                  8-9.    TP3 Voltages ................................................. .8-51
   4-5.    Abbreviated Receiver Accuracy                                                     S-10.    Hand Selection of Noise Filters .................. .8-58
           T e s t Table.. ..................................................... .4-9        8-11.    Autorange States.. ......................................... .8-59
  4-6.     Autorange T e s t .............................................. .4-10            8-12.    Hand Selection of C57 and Cl60................ .8-60
  4-7.     C-Message Filter Test.. ................................. .4-11                   8-13.    4935A C-Message Filter.. ............................. .8-61
  4-8.     3 kHz Filter Test.. .......................................... .4-12              8-14.    4935A 3 kHz Filter.. ...................................... .8-61
  4-9.     15 khz flat Filter Test.. .................................. .4-12                8-15.    4935A 15 kHz Filter...................................... .8-61
 4-10.     Program Filter Test.. ..................................... .4-12                 8-16.    4935A Program Filter.. ................................. .8-61
 4-11.     50 kBit Filter Test.......................................... .4-13               8-17.    4935A 50 kBit Filter.. .................................... .8-62
 4-12.     Notch Filter Test.. .......................................... .4-13              8-18.    4935A N o t c h Filter.. ...................................... .8-62
 4-13.     Impulse Noise DAC Test ............................. .4-15                        8-19.    4935A P/AR Filter ....................................... .8-62
 4-14.     Filter Circuit Parts List.. ............................... .4-23                 8-20.    4935A 150 kHz Low Pass Filter .................. .8-62
 4-15.     Abbreviated Distortion Test ........................ .4-24                        8-21.    4935A 110 kHz Low Pass Filter .................. .8-63
 4-16.     P/AR Filter R e s p o n s e s ................................ .4-25              8-22.    Bell 41009 C-Message Filter.. ...................... .8-63
                                                                                             8-23.    Bell 41009 3 kHz Filter................................. .8-64
   6-l. Reference Designation and                                                            8-24.    Bell 41009 15 kHz Filter.. ............................. .8-64
        Abbreviations ................................................. .6-2                 8-25.    Bell 41009 Program Filter.. .......................... .8-64
   6-2. Manufacturer Code List ............................... .6-8                          8-26.    Bell 41009 50 kBit Filter.. ............................. .8-65
   6-3. Replaceable Parts.. ........................................ .6-9                    8-27.    Bell 41009 P/AR Filter ................................ .8-65
                                                                                             8-28.    Bell 41009 Notch Filter.. ............................... .8-65




x /(xi blank)
(hctral Inii,rmi,ti~,,,




                                                                                 Model 4935A




              Figure f-1. Model 4935A f
                                          ransnhdon   Impairment Measuring set
Model 4935A
       . t                                                                                              General Information




                                                    SECTION I
                                       GENERAL INFORMATION


       l-l.    INTRODUCTION

       1-2.    This Operating and Service manual contains information to install, operate, maintain, and service
       the HI' Model 49:{5A Transmission Impairment Measuring Set (TIMS). Figure 1-l shows the HP Model
       49XA with cover and power cord. The manual is divided into eight major sections which provide the
       following information:

               SECTION I. GENERAL INFORMATION. Provides identification, specifications, related
               manuals, and user-repair information.

               SECTION II. INSTALLATION. Contains unpacking and inspection information, power
               requirements, packaging, and storage instructions.

               SECTION III. OPERATION. Includes an explanation of controls, connectors, indicators, and an
               automatic self check procedure. Describes measurement principles and front panel instructions for
               making each measurement.

                SFCTION IV. PERFORMANCE TESTS. C'          xtves test procedures required to verify that the
                instrument's performance is in accordance with the specifications.

                SECTION V. ADJUSTMENTS. Provides adjustment and calibration procedures.

                SECTION VI. REPLACEARLE PARTS. Lists and identifies the instrument assemblies and
                replaceable parts.

                SEXTION VII. MANUAL CHANGES. Cor tams information to backdate the manual for
                instruments with earlier serial numbers.

                SECTION VIII. SERVICE. Includes theory of operation, troubleshooting procedures, flowcharts,
                component locators, and schematic diagrams.

        1-3.    GENERAL       DESCRIPTION

        l-4.    HI' Model 49XA is a Transmission Impairment Measuring Set (TIMS) which measures wideband
       data and voice impairments. The frequency range over which measurements are made is 20 Hz to 110 kHz,
       in steps of I, 10, 100, 1000, or 10,000 Hz. There are four permanently stored, fixed frequencies -404, 1004,
       2804. and 271:s Hz. Any other four frequencies may be temporarily assigned and stored by the user.

        1-5.    INSTRUMENT         IDENTIFICATION

       l-6.      A IO character serial number (OOOOAOOOOO) is inscribed on the rear panel. The first four digits and
       the letter are the serial prefix. The serial prefix will change only if changes are made to the instrument; a
       Manual Change Sheet will be included with the manuals of any instruments affected. Thelast five numbers
       form the serial suffix which is unique to each instrument.

        1-7.    SPECIFICATIONS

        l-8.    Instrument specifications are listed in Table   I   -1.




                                                                                                                         l-l
                                                                                                                                                               Model 49:EA


                                                                       Table        l-l.   Specifications



TRANSMITTER                                                                                   RECEIVER

Frequency                                                                                     Frequency
Frequency Range . . . . . . . . . .20 Hz to 110 kHz                                           Frequency Range.. . . . . . . . . . . . .20 Hz to 110 kHz

                           Resolution                    Accuracy                                                               Resolution                           Accuracy

20-99,999       Hz               1 Hz          f .005% of output frequency                    20-9.999         Hz                   1 Hz                              kO.5     Hz
100-l 10 kHz                   10 Hz           t .012% of output frequency                     1 0 - 1 1 0 kHz                     10 Hz                                +5 Hz

Store and Recall Functions
SK Skip . . . At power up skips a band from 2450-2750 HZ

Frequencies      .     .   .    .    .   At    power     up   Fl    is 404 HZ
                                                                   F2 is 1004 Hz
                                                                   F3 is 2804 Hz
                                                                   F4 is 2713 Hz

Level                                                                                          Level
Range . . . . . . . . . . . . . . . .-40 to +13 dl3m                                           Range . .._........................                        -6Oto+13dBm
Resolution            . . . . . . . . . . . . . . . . . . . . . 0.1 dB                         Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.1 dB
Flatness . . . . . . . . . . . . . . . . . _ . . . . . . . _(in dB)                           Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (in dl3)

                                     FREQUENCY, Hz                                                                              FREQUENCY (Hz)
           20              200           15k       60k        85k             1 IOk                       20        50       200       15k         60k         85k       1 IOk
  z+13                                                                                          z-+13
+im                                                                                          5:
g;+1;                                                                                        Q---40
                                                                                             K.s

  3 -40                                                                                          3-60

Distortion:     (in dB from              fundamental)
(Includes harmonics, spurious and background noise within                                      Receiver accuracy not specified below 500 Hz when using
a filter with a 3 dB bandwidth of 4 kHz or 4 f0, whichever                                     13562      termination.
is greater.)
                                                                                               At 1004 kHz accuracy is fO.l dB from -20 to +I3 dBm.
                               FREQUENCY            (Hz)
          _ 30 Hz              100 Hz               4k              IlOk
                                                                                              Cross talk: >78 dB isolation @ 4 kHz, decreasing 6 dB per
                                                                                              octave above 4 kHz.




At 1004 Hz, 0 dBm, THD using a 4 kHz filter is more than
65 dB down from the fundamental.

Message Circuit Noise                                                                          Message Circuit Noise
Transmitter is quiet terminated                                                                Range (@ 6OOa and 9OOn) . . . . . . . . . . .O to 100 dBrn
                                                                                               @ 13516 lower limit is 7 dB higher
                                                                                               Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 dB
                                                                                               Accuracy . . . . . . . . . . . . . . . .+ 1 dB from IO to 100 dBrn
                                                                                                                                        +2 dB from 0 to IO dBrn
                                                                                               Filters . . . . . . . . . . . .C-Message, 3 kHz Flat, 15 kHz Flat,
                                                                                                                                                Program, 50 kBit

Specifications describe the instrument's warranted performance. Supplemental characteristics shown in shaded areas or in
italics   are    intended           to   provide    information      useful    in      applying     the    instrument      by    giving      typical,    but   non-warranted
performance          parameters.
Model 4935A                                                                                                                                         General       Information


                                                   T a b l e l - l . SpecificatilJns       (Continued)

                                                                                                                                                                                 1

TRANSMITTER                                                                            RECEIVER

Noise with Tone                                                                        Noise with Tone
Frequency . . . . . . . . . . . . . . 1004 Hz fixed tone                               Notch Filter. . . . . . >50 dB rejection from 995 to 1025 HZ
(For other specifications, see Level and Frequency)                                    Range (@ 600R and 900R) . . . . . . . . . . . . . . I O - 1 0 0 dBrn
                                                                                       Accuracy . . . . . . . . . . . . . . . . .          ?I dB from 20 to 100 dBrn
                                                                                                                                             *2 dB from 10 to 20 dBrn
                                                                                       (For other specifications, refer to Message Circuit Noise)

Signal-to-Noise    Ratio                                                               Signal-to-Noise Ratio
Frequency . . . . . . . . . . . . . . . . 1004 Hz fixed tone                           Signal Level Range . . . . . . . . . . . . . . . . . .          .-40 to +I 3 dBm
(For other specifications, see Level and Frequency)                                    Ratio Range . . . . . . . . . . . . . . . . . . . . . . . . . . .      IO to 45 dB
                                                                                       Resolution        .................................                             .I dB

3-Level   Impulse Noise                                                                3-Level Impulse Noise
Frequency . . . . .1004       Hz fixed tone or quiet terminated                        Level Range . . . . . . . . . . . . . . . . . . . . . . .     .-40 to +I3 dBm
                                    depending on filter selection                      Notch   Filter. . . . . . . . . . . . . . . . . . . .     .See Noise with Tone
(For other specifications, see Level and Frequency)                                    Threshold Ranges (@ 6OOfi)
                                                                                         Low . . . . . . . . . . . . . . . . . . . . . . . . . . . . .       .30 to 109 dBrn
                                                                                         Mid                  .4 dB above Low to a maximum of 109 dBrn
                                                                                         High : : : : .... .8 dB above Low to a maximum of 109 dBrn
                                                                                       Loss of Holding Tone Indication . . . . . . . . . . . .  Minus sign
                                                                                       Threshold Accuracy (above 40 dBrnl . . . . . . . . . . . . + 1 dB
                                                                                       Count Timer . . . . . . . . . . . . . . . 5, 15,60 min. or non-stop
                                                                                       Count Range . . . . . . . . . . . . . . .      O-9999 for each threshold
                                                                                       Count Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8per sec.

Noise-to-Ground                                                                        Noise-to-Ground
Transmitter is quiet terminated                                                        Range (@ 600R and 9OOfi) . . . . . . . . . . . . .50 to 130 dBrn
                                                                                       Resolution..................................                1 dB
                                                                                       Accuracy         ................................                             +I .5 dl3

P/AR   (Optional)                                                                      P/AR  (Optional)
Frequency . . Signal spectrum is a complex pulse train of                               P/AR Range. . . . . . . . . . . . . . . . . . .                  .O to 120 P/AR units
                  16 frequencies between 140 Hz and 3890 Hz.                             Resolution         ...........................                          1 P/AR unit
Level Range . . . . . . . . . . . . . . . . . . . . .-40 to 0 dBm                        Accuracy (from 30 to 110 P/AR units) . . . +2 P/AR units
Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 dB                  Level Range . . . . . . . . . . . . . . . . . . . . . . .         .-40 to +3 dBm
                                                                                         Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  .I dB

                                                                                       Temperature           Range:
                                                                                         Operating . . . . . . . . . . . . . . 0



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