6816985H01-F February 14, 2012
700/800 MHz Troubleshooting Charts: No Transmit Deviation Troubleshooting Chart 6.4-21
6.4.22No Transmit Deviation Troubleshooting Chart
MAEPF-27343-O
Check pin 7 of FL200.
When you PTT, is should
go HIGH (3V). If it does
not go high, check the
Patriot (U800).
Check pin 1 of FL200.
It should go up to 1.5V
when you PTT. If it doesn't
check C231. If C231
is good, replace FL200.
Make sure there is 3V
on pin 4 of FL200. If not
go to DC supply failure.
Check clock on pin 8
of FL200. The waveform
should look like TX
Audio 1 kHz Tone, trace 3.
Make sure DC on U202
is there. Make sure Y200,
pin 2 has 16.8 MHz
ref output.
Remove
SH201
Do
you see a
waveform like
TX Audio 1 kHz
Tone, trace
1?
Do
you see a
waveform like
TX Audio 1 kHz
Tone, trace
3?
Do
you see a
waveform like
TX Audio 1 kHz
Tone, trace
2?
Check Vdc on U201,
If no voltage,
replace U201.
Check R213, C231.
If components are
good, replace U202.
Check waveform on U201,
pin 1. It should
look like TX Audio 1 kHz
Tone, trace 2, Vdc~1.5V.
No RF TX
Deviation
Check waveform on test point
TP36 on VHF board.
It should look like TX Audio 1 kHz Tone,
trace 1 with Vdc ~1.5V.
PTT radio using
external PTT
switch
Set the radio to test mode CSQ.
Connect the radio to R4005B test box
or equivalent and inject a 1 kHz tone
mic signal with an amplitude sufficient
to provide a 3 kHz deviation out.
No
No
No
Yes
Yes
Yes
NOTE: This chart assumes you have gone through
the VOCON TX Audio Problem Section.
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