User Guide

CC Technical Documentation Troubleshooting - RF (Part 2)

RM-11

Incorrect RX VHF Frequency

Possible causes:

• Power supplies to PLL portion of Batman IC (N701) missing or low (VR7)

• Loop filter or resonator components missing or incorrectly installed

• 19.2MHz reference clock missing or low (C512)

• Programming is incorrect

• Component failure (PLL IC)

TX VHF Schematic

There are two fixed LOs — 346.2MHz for Cell band and 416.2MHz for PCS band. This is

the first LO for up-conversion. Refer to the frequency plan.

Monitor the probing point at C638 with a high-impedance RF probe for Robin LO.

A sufficiently strong and stable signal should be observed on the spectrum analyzer.

Monitor control voltage at C632. At this control voltage, the Robin LO is locked (it should

be between 1.2 and 1.8VDC).

Figure 10: TX VHF Schematic

Robin

Lock voltage

Loop filter

Resonator