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120X
RECEIVER TROUBLESHOOTING
No Service
n
Make sure phone has service programming and has phasing data stored. This can be verified with
n
QPST.
Check for Rx IF VCO (367.2MHz) to be on frequency. Measure Rx IF VCO control voltage. It should
n
be between 1 and 2 volts.
Check for RF signals after each of the filters, and major functional blocks.
n
Check for RF at Antenna -> Diplexor -> Duplexor -> LNA -> RF Interstage Filter -> Mixer -> IF.
n
Check LO frequency is locked and is present at the input of the mixer (RFR3300).
n
Check supplies to each functional block. Receiver runs off 2.75V.
n
TRANSMITTER TROUBLESHOOTING
Check for I and Q going into RFT3100.
Check for LO input into RFT3100. Level
should be about –15dBm.
Check for Tx IF VCO Frequency and
control voltage.
Tx IF VCO frequency is 457.2MHz for
800MHz CDMA and AMPS, and
527.2MHz for PCS CDMA.
Control voltage at 457.2MHz is about
1volt, and 2volts at 527.2MHz.
Check for Tx IF (near the Tx IF Filter)
Tx IF is 228.6MHz for 800 MHz CDMA
& AMPS
Tx IF is 263.6MHz for 1900 MHz CDMA
Check for Tx RF at RF filter input and at
PA input.
Product Support Tools
63
1/15/02
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Table of Contents
Troubleshooting
