Motorola GTR 8000 - Tuning the UHF Preselector; Tuning a Duplexer; Field Tuning Overview

GTR8000BaseRadio
5.8.2.3.1TuningTheUHFPreselector
ProcedureSteps
1TurnthebaseradiopowersupplyON(toprovidea50Ohmtermination).
2Adjustthesignalgeneratortothefrequencycalculatedin5.8.2.1.1CalculatingTheUHFAlignmentFrequency
ForaSingleReceiveFrequency,page5-8or5.8.2.1.2CalculatingTheUHFAlignmentFrequencyForMulti
ReceiveFrequencies,page5-9.Setthelevelto+5dBm.
3InserttuningprobeintocavityU2andadjusttuningscrew2foraPEAK.
4Tightentensionnutontuningscrew2toatleast12in-lbandnetunetuningscrew2foraPEAK.
5KeeptuningprobeincavityU2andadjusttuningscrew3foraDIP.
6Tightentensionnutontuningscrew3toatleast12in-lbandne-tunetuningscrew2foraDIP.
7InserttuningprobeintocavityU3.Decreaseoutputfromsignalgeneratorto–5dBm.
8Adjusttuningscrew4foraDIP.
9Tightentensionnutontuningscrew4toatleast12in-lbandne-tunetuningscrew4foraDIP.
5.9TuningaDuplexer
Duplexermodulesshippedwithbaseradiosaretunedatthefactory.Ifaduplexermustbereplacedintheeld,the
unitmustbeinstalledandtunedspecicallytothetransmitandreceivefrequencypairfortheparticularbaseradio.
5.9.1FieldTuningOverview
Thesetuningproceduresarevalidforchannelswithabandwidthof200kHzorless.Ifbandwidthismore
than200kHz,theduplexermustbetunedbytheservicedepot.
Theduplexermoduleiscomprisedofthreelow-pass/high-notchcavitiesandthreehigh-pass/low-notchcavities.
EachsetofthreecavitiesprovidesbandpasslteringforeitherthetransmitRFsignalorthereceiveRFsignal.In
general,theduplexermustbetunedsothatthetransmitcavitysetpassesthetransmitsignalandrejectsthereceive
signal;concurrently,thereceivecavitysetmustbetunedtopassthereceivesignalandrejectthetransmitsignal.
5-126871022P86-A-November2012