Uhf Synthesizer Troubleshooting - Nokia RM-11 Series Troubleshooting Manual

CC Technical Documentation

UHF Synthesizer Troubleshooting

UHF LO frequency varies with channel and can be quickly calculated using the UHF
Synthesizer in the Phoenix in RF menu. Check to see if the LO is actually locked. Set a
channel and check the status of the UHF LO within a very narrow span of 100KHz. You
should see the LO virtually immobile. Measure nominal UHF LO signal levels with an RF
probe. If you do not see the presence of any LOs, check the DC voltages at the following
locations:
• R513, VR1A, supply line for UHF PLL IC, should be 4.76VDC
• R515, VR4, supply line for VCO IC, should be 2.76VDC
Issue 2 09/2005
© 2005 Nokia Corporation
Troubleshooting - RF
Confidential
RM-11
Page 33