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Page Title:
Transmitter Circuit Tests-continued |
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|  TM 11-5820-509-35
Item
Indication
Probable trouble
Procedure
2
No signal at transmit if. input
Balanced modulator circuit of
Repair AM-3507/PRC-47 (para 3-
A2J3.
amplifier-modulator A2 defec-
13b ) or replace defective
tive.
module.
3
No 500-kHz standard oscillator
a. Check continuity from K4-3 to
signal at A2J2 of amplifier-
circuit on main chassis defective.
K4-6 and J3-A2; repair as
modulator A2.
required. Refer to frequency
generation tests (para 3-5c ).
b.
500-kHz relay K4 defective.
b. Check for signal at K4-3 and
K4-6 when relay operated.
Replace K4 if contacts remain
open when 26.5-volt vox signal
is applied to K4-1.
c.
500-kHz standard oscillator
circuit in amplifier-modulator A2
A2J2: repair AM-3507/PRC-47
defective.
module.
4
No transmit signal at if. output
If. amplifier stages in amplifier-
Repair AM-3507/PRC-47 (para 3-
(A2J1) of amplifier-modulator
modulator A2 defective.
13b ) or replace defective
A2.
module.
st
5
No transmit rf signal at 1 rf
a.
Transmit relay A2K1 in am-
a. Check signal at J4-A3 (main
amplifier grid (A3J1) of signal
plifier-modulator defective.
chassis) when A2K1 operated.
data translator A3.
Check capacitor C2 on main
chassis for shorts; repair circuit
on main chassis, repair AM-
3507/PRC-47 (para 3-13b ), or
replace defective module.
b.
If. circuit on main chassis
defective.
J6-A1; repair if necessary.
c.
Transmit mixer circuit or
c. Repair CV-1377A/PRC-47 (para
amplifier A3Q15 in signal data
3-13c ), or replace defective
translator defective.
module.
6
No transmit rf signal at grid of
a.
Rf drive circuit on main chassis
a. Check continuity from J7-AI to
power amplifier (J104).
defective.
PA socket XV101-4; repair
circuit as necessary.
b.
A1c circuit at power amplifier
grid defective.
of L102 (normal 29 ohms), R104
(normal 47K ohms). R119
(normal 27K ohms). and check
capacitors C101A and C141 for
shorts. Repair circuit or replace
defective components.
c.
A1c circuit on main chassis
c. Check continuity from L102-2
defective.
to FL2-19, from FL2-6 to J3-2,
from C101A to FL2-18, and
from FL2-5 to J3-1; repair
circuits as necessary.
d.
A1c circuits in PA filter box
d. Check continuity from FL2-5 to
FL2 defective.
FL2-18, and from FL2-6 to FL2-
19: check each terminal for short
to chassis ground. Repair circuit
or replace C210, C211, C223.
C224, C231, C232, L208, or
L209 as required.
e.
A1c circuit in amplifier-
e. Repair AM-3507/PRC-47 (para
modulator A2 defective.
3-13b ) or replace defective
module.
7
XMTR OUTPUT meter M101
a.
Power amplifier output circuit
a. Check continuity of L110,
indicates little or no output
defective.
L111, and L112 and from L112
power.
to K101 (NO): repair circuit or
replace defective component.
b.
Rf detector circuit defective.
b. Check continuity of T101, R129
(normal 470 ohms), and M ADJ
pot R117 (normal 5K ohms).
Verify that CR102, CR103,
C106A/C106B and not shorted.
Repair defective circuit or
replace component.
3-84
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