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.
2
