Tx Rf (Uhf R1/700-800 Mhz) - Motorola ASTRO XTS 5000 Detailed Service Manual

Troubleshooting Charts: TX RF (UHF R1/700-800 MHz)
5.16 TX RF (UHF R1/700-800 MHz)—Page 1
No or low
TX power
Place XCVR and VOCON
into the analysis fixture.
Key up. Measure RF
power at antenna port
TX
power OK?
No
Use a spectrum analyzer
and high-impedance RF
probe. Measure TXRF
at TP11
Frequency
OK?
Yes
Level
about
-3 dBm?
Yes
Measure RF level
at driver amp
outlet, C107.
RF level OK?
Approx. +26 dBm
Yes
6881094C31-D
Check coaxial
Yes
connector and
cable assembly
No Check
FGU
No Check
FGU
No
1
Measure RF level
at PA output,
C103.
No
Level about
+36 dBm?
Yes
Measure RF levels
at C103 and D701-
cathode. Calculate
switch loss
No
Loss < 1 db?
Yes
Measure RF levels
at D701-cathode and
TP02. Calculate
harmonic filter loss
No
Loss < 2 db?
Yes
Go to
VOCON TX
AUDIO flowchart
5-31
2
Check
switch
Remove
SH700,
repair defects
MAEPF-27475-B
July 21, 2004