Now with the gqrx window open, I turn on the ptt switch on the patch cord and confirmed the signal was being received by gqrx. It should be a narrow spike at this time. (Probably doesn’t need to be said but make sure the antenna on the handheld is properly terminated into a dummy load or an antenna.)<\/div>\n
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I slow increase the volume until the centre peak of the received signal dipped to it’s lowest point compared with the first side bands.<\/div>\n
(Spend a little time going back and forth until you get precisely the lowest point.) Now the handheld is calibrated at the correct deviation.<\/div>\n
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Next step is the repeater.<\/div>\n
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On the controller, while still TXing with the hand held set the rx level as per the controller manual which usually is 1v P to P which is .35v rms.<\/div>\n
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Now switch the frequency in GQRX to the repeater output and adjust the TX audio pot until I get the lowest point of the null just like when I calibrated the hand held.<\/div>\n
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I’ve since had a chance to verify the deviation with a service monitor and with this method I was able to achieve 4.6 KHz deviation which is better than most of the repeater users radios.<\/div>\n
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Instead of gqrx any other SDR spectrum analysers could be used. In Windows I think SDR# is one of the better ones.<\/div>\n
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When I get a chance I’ll take some photos and screen shoots to up date the post with.<\/div>\n