User Guide

Nokia Customer Care RF Description and Troubleshooting

6235/6235i/6236i (RM-60)

Rx VHF LO Troubleshooting

The VHF LO operates at a fixed frequency of 256.2MHz. It is the second LO for down-

conversion to I and Q for baseband processing. Use the following steps to troubleshoot

the VHF LO.

1. Monitor the test point at C7100. Ensure that a locked and stable 256.2MHz with

amplitude ~ –60dBm is present on the spectrum analyzer (or, with a high

impedance probe, ~ -2dBm at C7104).

2. Monitor the control voltage at C7100. The control voltage at a locked state must

be between 1.2 and 1.7 Vdc for the proper operation of the VHF LO.

Figure 55: Rx VHF LO test points