TM 11-6625-847-45
b. For testing the receiver IF module of the RT-
NOTE
662/GRC, the external audio signal from the COMMON
When partial reference designators
AUDIO 600 Ω IN connector is connected directly to pin 3
are used, prefix with common
of receiver IF module connector J17. The 1.7500-mc
module
tray
A1A2
reference
signal is supplied to pin A4 of connector J17 from the
test set IF OSCILLATOR (1) 1.75 MC module. From the
designator A1A2, unless otherwise
mixer module on the test set, pin A2 of connector J17
specified.
receives a two-tone signal from either the internal IF
oscillator modules of the test set, 1.7525 MC 1.7515
The 1.75-mc input to amplifier assembly A1 is amplified
MC, or an external two-tone signal generator source,
approximately 20 decibels (db). The input to the
depending on the position of RCVR IF AGC SYNC
amplifier is coupled to transmit IF transistor A1Q3 by
switch S6. The IF output of the receiver IF module is
capacitors A1C3 and A1C6. The amplifier output of
amplified by amplifier, assembly Al and supplies to test
transistor A1Q3 is coupled through capacitor A1C15 to
point AMPL IF OUT.
the voltage divide circuit consisting of resistor A1R20
and the collector-- to emitter and collector-to-base
resistance of transistor A1Q4. The amount of control
1-19. RCVR IF TEST SELECTOR Switch S4
provided by this variable voltage divider depends on the
dc level of the base of A1Q4 that is controlled by
variable resistor A1R14. Resistor A1R14 is used to
a. RCVR 'IF TEST SELECTOR switch
X4 controls
adjust the overall gain of the amplifier. The output of
the selection of the RCVR IF test points HI
and LO for
the voltage divider is coupled to the base of transistor
voltage measurements of the receiver IF
module at
A1Q6 by capacitor A1C19. The output from transistor
connector J17.
The positions of the
switch are
A1Q6 is coupled to connector A1J1 by transformer
discussed in b below.
A1T2 for application to the IF OUT connector.
b. Position 1 connects to the -33-volt dc input
1-21. Synthesizer Test Tray A1A3
voltage at pin 6 of J17. Position 2 monitors the level of
the voltage controlled by RF GAIN control resistor R4 at
pin X of connector J17. Position 3 monitors the voltage
NOTE
level controlled by BFO TONE control resistor R3 at pin
Prefix reference designators with
11 of connector J17. Position 4 connects to pin 29 of
synthesizer test tray A1A3 reference
connector J17 for audio output measurements. Position
designator A1A3, unless otherwise
5 monitors the S-meter voltage at pin 7 of connector
specified.
J17.
c. The CW position of the SERV SEL switch on
connections, and mechanical coupling available on tray
the test set supplies +20-volt dc to BFO TONE control
A1A3 for testing the mc synthesizer module, the
resistor R3 at pin 10 of connector J 17. The ON position
frequency standard module, the 10 and 1-kilocycle (kc)
of RCVR IF AGC switch 55 supplies -20-volt dc to pin
synthesizer module, the 100-ke synthesizer module, and
15 of connector J17. Pin 13 of connector J17 if
the frequency divider module of the RT-662/GRC. On
grounded when the XMIT STATUS switch on the test set
tray A1A3 the testing of an individual module requires
is set to TUNE. The REC/SMIT switch on the test set
stimulus inputs from one or more of the other modules
supplies +20-volt dc to pin 9 when in the SMIT position
that are to be tested by the tray.
and ground when in the REC position. RF AGC
OUTPUT test point is connected to pin 5 of connector
b. The +27-volt dc primary power input to tray
J17 for age measurements. AGC SYNC test point is
A1A3 is controlled by POWER switch S1. In the ON
connected to pin 5 of connector J17 for age
position, POWER switch S1 supplies +27-volt dc
measurements. AGC SYNC test point J14 externally
primary power to POWER indicator DS1, to pin 3 of
triggers an oscilloscope with a +27-volt signal when
frequency standard
AGC SYNC switch S6 is set to ON.
1-20.
Common Module Tray A1A2 Electronic
Circuits (fig. 6-9)
Change 2
1-17
Previous Page
