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Page Title:
Table 4-2. Checkout/Troubleshoot the Receiver-Transmitter RT-1277/URC-92 (cont) |
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|  TM 11-5820-873-34
Table 4-2.
Checkout/Troubleshoot the Receiver-Transmitter RT-1277/URC-92--Continued
STEP
ACTION
INDICATION
NEXT STEP
6b
Set FREQ CONTROL switch to B. Repeat step 6a
Yes: step 6c No: step 211
using FREQUENCY B controls.
frequency.
6c
Set FREQ CONTROL switch to A. Pull out VFO
VFO lamp illuminates.
Yes: step 6d No: step 215
PULL control (VFO on).
6d
Connect frequency counter to oscilloscope vertical
Frequency counter indicates 2.0000 MHz 5 KHz
Yes: step7a No: step 218
amplifier output. Connect oscilloscope across dummy
minimum.
load. Set FREQUENCY A controls to 2.000 MHz. Key
microphone. Rotate VFO PULL control through its
entire range.
7a
Set FREQ CONTROL to A XMT B RCV. Key
Frequency counter indicates 1.6000 MHz and front panel
Yes: step 7b No: step 223
microphone. Rotate FREQUENCY B, 10 KHz control.
readouts agree.
7b
Release microphone key. Observe front panel readout
No readout change occurs
Yes: step 82 No: step 223
and rotate FREQUENCY A, 10 KHz control.
8a
Disconnect antenna coupler control cable. Disconnect
Audio VTVM indicates -10 dB or more.
Yes: step 8b No: step 225
CW key and mic. Remove dummy load from ANT jack
1A8J1. Connect signal generator to ANT jack 1A8J1.
Connect Audio VTVM to PHONE jack 1A1J3. Set
mode switch to LSB. Set FREQ CONTROL to B Set
FREQUENCY B controls to 29.9994 MHz. Adjust
VOLUME CONTROL for VTVM indication of -20 dB.
Set signal generator output level to 0.5 uV. Adjust
signal generator frequency to approximately 29.9994
MHz, until VTVM indication peaks.
8b
Repeat
step
8a
substituting
the
following
Audio VTVM indicates -10 dB or more.
Yes: step 9a No: step292
FREQUENCY B, and signal generator frequency
settings.
16.0100 MHz 10.0100
MHz 7.5100 MHz
5.0100 MHz
3.5100 MHz
2.0100 MHz
1.6100 MHz
9a
Set mode switch to USB Return FREQUENCY B
Audio VTVM indicates at least -10 dB or more.
Yes: step 9b No: step 295
switches to 29.9994 MHz. Adjust signal generator
frequency to approximately 29.9994 MHz, until VTM
indication peaks.
9b
Set mode switch to AM, FREQUENCY B controls to
VTVM indicates less than -20 dB.
Yes: step 9c No: step 242
29.9994 MHz. Signal generator output level to 3.0 uV,
frequency to 29.9994 MHz, 30%, 1 KHz modulation.
Adjust signal generator for peak VTVM indication.
Adjust VOLUME control for -10 dB VTVM Indication.
Remove modulation from signal generator output.
9c
Set mode switch to LSB. Set FREQUENCY B
At each position, noise blanks momentarily then returns.
Yes: step 10 No: step 297
switches to 20.000 MHz. Disconnect VTVM from
PHONE jack. Increase VOLUME control until noise is
heard. Rotate 1 MHz control thru each of its positions.
10
Set mode switch to OFF. Disconnect control cable at
Meter indicates a range between + 12 and +22 VDC 10%
Yes: step 11 No: step 264
receiver-transmitter 1A8J4.
Connect multimeter
between ACCESSORY Connector 1A8J4-P and
ground. Set mode switch to AM. Slowly adjust
ANTENNA coupler CONTROL gain control 1A2R2
thru its entire range.
11
Reset gain control 1A2R2 to 14.5 VDC 0.5 VDC.
Step 12
Set mode switch to OFF. Disconnect dummy load
from antenna jack lA8Jl. Connect RF and control
cables between the receiver-transmitter and a known
good CU-2229/URC-92 Antenna Coupler Connect a
50 ohm dummy load to the Antenna Coupler antenna
post and ground post using a BNC/clip lead cable.
4-3
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