User Guide

TUNING INSTRUCTIONS

9618ARo

6–3–9

NHC–4

Technical Documentation

Tuning Steps of Radio Unit

1. Bias Current Tuning

The purpose of this tunig is to optimize transmitter‘s efficiency.

Bias tuning is needed if:

– PLL circuit (N501) is replaced

– any of power amplifiers (CLY5, CCY15) duplex filter is replaced

– any of power amplifiers resistors is replaced

This affects only power consumption and thus gain and linearity of power ampli-

fier.

Analog bias current tuning:

– Start the service software and go to ”Main” menu.

– Select ”Service – Tunings – Bias current tunings”

– Measure step1 current consumption from power supply current display and

input it to Service software prompt.

– Adjust first analog mode bias current to the target value displayed in tuning

dialog by using arrow– or PgUp/PgDwn –keys.

Digital bias current tuning:

– Change to digital mode bias tuning with <Tab> and proceed as in analog

mode tuning.

After this digital bias tuning the TX linearity can be checked: the highest peak

+ 24.3 kHz peak should be 29.5 dB below the highest peak. Adjust spectrum

analyzer: center frequency; 848.7 MHz, Span; 100 kHz, Res BW; 1 kHz

– Press <Enter> to store the value to the phone and exit or <Esc> to exit with-

out storing.