5-40 Troubleshooting Charts: RX RF Failure
RX RF Failure – Page 7
5
Remove SH10 and SH4.
Measure RF and IF level at mixer
and compute mixer conversion
gain.
For VHF radios:
Input of L328 and output of L503.
For UHF1/UHF2 radios:
Non gnd of C1900 and output of
L503.
For 7/800 radios:
Input of C488 and output of L503.
For 900 radios:
Input of C488 and output of L503.
Note: RF Test frequency used:
VHF: 154.275MHz
UHF1: 424.975MHz
UHF2: 485.075MHz
700: 769.0625MHz
800: 860.0625MHz
900: 938.0625MHz
IF: 109.65MHz
Measured with a High Frequency Probe for relative comparisons and troubleshooting
only. Actual S21 gain or loss may differ if the test point is not 50 ohms.
Mixer gain about
0-3dB?
8
No
Yes
13
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