User Guide

PAMS
Technical Documentation
NHD–4
Disassembly & Troubleshooting
Page 27
Original 11/97
Transmitter Troubleshooting
Introduction
Troubleshooting the NHD–4 transmitter is very straight forward.
Operation of the transmitter circuit changes little from AMPS to CDMA
mode, only the nature of the signal transmitted is distinctly different. A
substantial amount of information regarding the health of the transmitter
can be determined with just a simple DMM. The detector voltage will
provide you a sound estimate of the output power. Collector and base
voltages will inform you if biasing is correct on the gain stages (drain and
gate for CLY–10 V113). And the various control signal had their DC
voltage characteristics detailed in the Functional Description. An RF
probe can also be used to quickly determine if a gain stage or filter is
functioning properly.
Below are a number of techniques to test the transmitter, beginning with a
means to simply turn it on. Service Software features that provide manual
transmitter controls are detailed. Node voltages RF power levels and a
chart of gains and losses are provided. Means to test the various TX
control features are explained.
Service Software Quick Checks
The Service Software has a number of features that allow you to quickly
test out the functionality of the transmitter in both the CDMA and AMPS
modes. The following two quick checks simply turns the transmitter on in
either of these modes.
AMPS TX Quick Checks with Service Software
From the Service Software select the AMPS Quick Checks option from the
Testing menu. A window will appear. Within this window are numerous
AMPS related controls for the phone, including a means to turn on the
AMPS transmitter. This is done by simply selecting the AMPS power level
0–2 through 7. Measure the output power using a spectrum analyzer,
power meter or RF communications test set.
AMPS TX
Power Level
AMPS TX
Output Power
(dBm)
0–2 27.0
3 23.0
4 18.0
5 14.0
6 10.0
7 8.0