With AO-51 in mode V/S i start to test a wave guide filter model ITS 1653C made by ITS corporation Mc Murry PA. The wave guide centered on 2401Mhz with a band pass covering 2400 to 2402Mhz with a very low insertion loss.
The first test made on my last AO-51 pass confirm all the qrm out of the passband if effectively reduced a lot.
More test will be needed to confirm if the filter effectively help my AIDC downconverter reception
P.S. when i dismantle the antenna coax from the AIDC connector i saw the N female connector full of white rust. Even with a carefull taping only the antenna connector show this type of corosion. I suspect the N male adaptor and the is made of a different alloy than the AIDC N connector. After one year at the top of the tower the corrosion take his toll and it will a good thing to check your AIDC downconverter connector condition.
I don't know how i was able to hear on 2401mhx with a so white powder rusted connector?
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Luc Leblanc VE2DWE Skype VE2DWE www.qsl.net/ve2dwe DSTAR urcall VE2DWE WAC BASIC CW PHONE SATELLITE