User Guide

PAMS
Technical Documentation
RAE-3
8. Troubleshooting
Page 8 – 109
Issue 1 06/01
5 RF related
Introduction to troubleshooting
Measurements must be done using Spectrum Analyzer with high–frequency
high–impedance passive probe (LO–/reference frequencies and RF–power
levels) and Oscilloscope with a 10:1 probe (DC–voltages and low frequency
signals).
The RF–section is build around one ASICS Hagar (N505). For easier trouble-
shooting, this RF troubleshooting document is divided into sections.
Before changing Hagar, please check the following things: Supply voltages are
OK and serial communication are coming to Hagar.
Please note that the grounding of the PA–module is directly below PA–module
so it is difficult to check or change. Most RF semiconductors are static dis-
charge sensitive! So ESD protection must be taken during repair (ground
straps and ESD soldering irons). Hagar are moisture sensitive so parts must be
pre–baked prior to soldering.
Apart from key–components described in this document here are a lot of dis-
crete components (resistors, inductors and capacitors) which troubleshooting is
done by checking if soldering of the component is done properly, for factory re-
pairs (checking if it is missing from PWB). Capacitors can be checked for short-
ening and resistors for value by means of an ohmmeter, but be aware in–circuit
measurements should be evaluated carefully.
Please be aware that all measured voltages or RF levels in this document
are rough figures. Especially RF levels varies due to different measuring
equipment or different grounding of the used probe.
5. RF related :
5.1 EGSM receiver
5.2 PCN receiver
5.3 EGSM transmitter
5.4 PCN transmitter
5.5 Synthesizer
5.6 Frequency lists