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Page Title:
Table 3-2. Checkout/Troubleshoot the Receiver-Transmitter RT-1277/URC- 92 |
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|  TM 11-5820-873-34
Table 3-2. Checkout/Troubleshoot the Receiver-Transmitter RT-1277/URC- 92
STEP
ACTION
INDICATION
NEXT STEP
1
Remove top and bottom covers Connect 115
VAC power cable to POWER connector 1A8J3
Connect 50 ohm dummy load thru a thruline
wattmeter to ANT jack lA8Jl Connect a known
good Antenna Coupler CU-22291URC-92 to AC-
CESSORY jack 1A8J4 Set XMIT GAIN control
fully counterclockwise Set VOLUME control
clockwise, 1/4 turn Push VFO control in (off) Set
DIM control fully clockwise
2a
Set mode switch to LSB
ANTENNA COUPLER CONTROL meter lamp ii-
Yes step 2b
luminates
No step 17
2b
Check pilot lamp and display
Pilot lamp and display illuminate
Yes: step 2c
No: step 19
2c
Rotate DIM control one position counterclock-
Pilot lamp and display intensity dim, then go out
Yes: step.3a
wise Then rotate DIM control another position
Meter lamp retain intensity, then goes out
No: step 132
counterclockwise
3a
Set FREQ CONTROL switch to A Set FRE-
LOW FREQ LIMIT lamp illuminates and speaker
Yes: step3b
QUENCY A control to 1 5000 MHz Rotate 100
noise level decreases
No: step 21
KHz control thru positions 4, 3, 2, 1, and 0
3b
Rotate 100KHz control thru positions 6,7,8, and
LOW FREQ LIMIT lamp is out and receiver/
Yes: step3c
9
transmitter is enabled
No: step 132
3c
Set FREQ CONTROL switch to B
Set FRE-LOW FREQ LIMIT lamp Illuminates
Yes step 3d
QUENCY B controls to 1 5000 MHz Rotate 100
No: step 132
KHz control thru positions 4, 3, 2, 1 and 0
3d
Rotate 100 KHz control thru positions 6, 7,8, and
LOW FREQ LIMIT lamp is out.
Yes: Step 3e
9
No: step 132
3e
Set FREQ CONTROL switch to A Set FRE-
Noise is heard In speaker.
Yes: step 3e
QUENCY A controls to 16000 MHz Increase
No: step26
VOLUME control until noise is heard in speaker
3f
Connect a known good headphone at 1A1J3
Noise is heard in headphone.
Yes step 3g
No: step 132
3g
Disconnect headphone. Connect known good
Noise is heard In ear piece of handset
Yes: step 3h
handset at MIC connector 1A1J1
No step 140
3h
Disconnect handset. Rotate RF GAIN control
Front panel meter reading increases to almost
Yes: step4a
counterclockwise and observe meter
full scale deflection
No: step 28
4a
Return RF GAIN control to fully clockwise posi-
Sidetone is heard in speaker
Yes: step 4b
tion and VOLUME control to l/4 turn clockwise
No: step 29
Connect a known good CW key at the KEY jack
Set FREQUENCY A controls to 29 9950 MHz
Set mode switch to CW Depress CW key
4b
Depress CW key and observe wattmeter.
Wattmeter indicates 100W 10W
Yes: step 5a
No: step 33
5a
Connect oscilloscope across dummy load. Set
Oscilloscope displays waveform similar to Fig
Yes: step 5b
oscilloscope to 2V/division Set FREQUENCY A
3-2A, less than 2 V peak-to-peak
No: step 84
controls to 29 9995 MHz Set mode switch to
LSB Connect microphone to MIC connector Key
microphone and observe oscilloscope.
5b
Set mode switch to USB Key microphone and ob-
Oscilloscope displays waveform similar to Fig
Yes: step 5c
serve oscilloscope.
3-2A, less than 2 V peak-to-peak
No: step 84
5c
Set oscilloscope to 50 V/division Key, and speak
Oscilloscope displays waveform similar to Fig
Yes: step 5d
into microphone Increase XMT GAIN control un-
3-2A, 190 V peak-to-peak maximum
No: step 85
til no further increase m peak-to-peak voltage is
observed
5d
Set mode switch to LSB. Key and speak into
Oscilloscope displays waveform similar to Fig
Yes: step 5e
microphone Increase XMT Gain until no further
3-2A, 190 V peak-to-peak maximum
No: step 132
increase In peak-to-peak voltage is observed
5e
Set mode switch to AM Key, and speak into
Oscilloscope displays waveform similar to Fig
Yes: step 6a
microphone Observe oscilloscope
3-2B, modulated carrier signal
No: step88
6a
Connect frequency counter to oscilloscope ver-
Yes: step 6b
tlcal amplifier output. Connect oscilloscope
agree for each frequency
No: step 132
across dummy load Set FREQUENCY A controls
to 1 6000 MHz Turn XMT GAIN Control fully
counter clockwise Key microphone Starting
with 100 Hz control, rotate each FREQUENCY A
control through its entire range
3-2
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