SECTION I GENERAL

SECTION I

GENERAL

Weight ......................... 366 Ibs (approx.)

1. Purpose and Scope

References .................. TB 9-6625-961-50.

a. This bulletin contains calibration instructions for

b. Specifications

Synthesizer Depot Test Set, Litcom Model No. 7900

(synthesizer depot test set), and is used by maintenance

Input requirements

103.5 to 126.5 volts, 54 to

calibration personnel. Since maintenance calibration

66 Hz, single phase.

personnel are trained and qualified in the use of test and

Oscillator frequencies... 1.0, 1.4, 1.5, 1.6, 1.7, 1.75,

measuring equipment, detailed instructions concerning

1.8, 1.9, 2.0, 2.1, 2.2,

the operation and use of these equipments are not

2.3, 2.9, 4.75, 13.0, 14.0,

contained in this bulletin.

15.0, 16.0, 17.0, 18.0,

19.0, 20.0, 21.0, 22.0,

23.0,26.75,27.25,27.75,

b. Integrated within this bulletin is an illustration

29.05, 30.0 MHz (Tol

which shows equipment setup required.

erance: 5 parts per

10-;) 34.0, 80.875, 86.0,

2. Reporting of Technical Bulletin Improvements

86.625, 87.125, 87.375,

The reporting of errors, omissions, and recom-

92.5, 138.0, 144.25,

mendations for improving this publication by the

147.0, 148.75, 151.75,

individual user is encouraged. Reports should be

and 156.75 MHz (Tol

submitted on DA Form 2028 (Recommended changes to

erance: 20 parts per

Publications) and forwarded direct to Commanding

10").

General, US Army Electronics Command, ATTN:

VHF amplifier ............... 14 db gain at 130 to 190

AMSEL-MA-CFA, Fort Monmouth, N.J. 07703.

MHz.

Multimeter .................... 0 to 1000 volts dc and ac,

3. Description

0-500 milliamperes, 0

The Synthesizer Depot Test Set, Litcom No. 7900 is a

to 10 amperes and 0 to

depot maintenance test unit used to test, troubleshoot,

20 megohms.

and maintain the modules and printed circuit boards

Frequency doubler ....... input 80.0 to 92.5 MHz.

contained in the Synthesizer, Electrical Frequency 0-

output 160 to 185 MHz.

1488/FR, which is a component part of Receiving Set,

Power supply output

Radio AN/FRR79; Transmitting Set, Radio AN/FAT-76;

voltages ................. +18,-9 volts do, ±3

and Transmitting Set, Radio AN/FAT-77.

The

percent

synthesizer depot test set contains the necessary

c. Program Data.

switching and patching functions to interconnect the ap-

Calibration interval ....... In accordance with

propriate test circuits that provide simulated test signals,

TB 750-236

dc operating voltages, and monitoring facilities to the

Time required for

input and output pins of the module or printed circuit

calibration .............. 1 hour

board under test. The synthesizer depot test set

Calibration level ........... Depot maintenance

provides the operator with the capability of fault isolation

4. General Instructions

to a particular printed circuit board of a module or to a

a. Calibration Reporting. During the performance

particular circuit or component on a printed circuit board.

of the calibration procedures included in this manual,

The synthesizer depot test set is a self-contained unit

annotate DA Form 2416 (Calibration Data Card) in

consisting of three major components all housed in an

accordance with TM 38-750.

electrical equipment cabinet. The major components

constituting the synthesizer depot test set are matrix

b. Removal.

Do not remove any of the

oscillator 1A1, synthesizer matrix test panel 1A2, and

subassemblies to be calibrated from its protective case

power supply 1A3. A utility drawer for cable storage is

unless necessitated by equipment connections and/or

also provided. Additional data is listed in a, b, and c

components to be adjusted which cannot be reached

below.

from the external parts on the synthesizer depot test set.

c. Unit Under Test. Synthesizer depot test will be

a. Identification.

referred to as "unit under test" throughout this

procedure.

Nomenclature............... Synthesizer Depot Test

Set Litcom Model 7900.

Size . ........................... 493/8 by 21 1/2 by 25 3/4 in.