Table 5-1. Test Equipment Required

TM 11-5820-917-13

Test Equipment Required

Table 5-1.

Recommended manufacturer and type

Item

Tektronix 455 (or 465)

Oscilloscope

Hewlett Packard 5300B

Frequency Counter

Simpson 460 (or Beckman 3020)

Multimeter

Microlab FXR TA-5MN

Termination, 2 watts

Tektronix 011-0059-02

Attenuator, 20 dB

Hewlett Packard 141T

Spectrum Analyzer

Hewlett Packard 8552B

with IF Section

Hewlett Packard 8553B

RF Section

TCS-4B/1024 Unit (BR Communi-

Sweep Generator

cations)

Hewlett Packard 651A

Audio Oscillator

Watkins Johnson MIC

Mixer

Kay Model 432D

Attenuator (Variable)

Lambda LL-903-OV, or LP-552-FM

Power Supply

or HP 6200B

(35 VDC Lab Type)

by replacing the faulty assembly with a known good assembly. The performance

test of paragraph 5-29, figures 5-2, 5-3, 5-4, 5-6, 5-7 and 5-8, and schematics

of Section 7 provide the measurement data that can be used for fault isolation.

5-10. OVERVOLTAGE PROTECTION. The 4028 power supply incorporates an over-

voltage protection device, U9 (figure FO-34/1. The overvoltage device accomplish-

es circuit protection by effectively short circuiting the output terminals of the power

transformer when the trip voltage limit is exceeded. The overvoltage device is

connected across the 11 volt terminals and trips at 17 volts. When the trip voltage

is exceeded, the input power fuse is normally blown. This condition should be

noted when troubleshooting and line voltage checked before trying to turn on the

receiver.

5-11.

ADJUSTMENT

PROCEDURES

5-12. GENERAL. All initial adjustments to the receiver were made at the factory

before shipment. The following procedures are provided for use following a repair

or as required during the performance verification test.

5-2