[amsat-bb] Re: 2 Meter TV Interference

Gordon JC Pearce gordonjcp at gjcp.net
Wed Dec 7 00:01:43 PST 2011

On Tue, 6 Dec 2011 21:17:55 -0600
Wyatt Dirks <wyattdirks at msn.com> wrote:

> Just recently I have been having troubles with a neighbor while I am working the FM satellites(SO-50 and AO-27). The setup I am currently using is my mobile setup because I am unable to put a base station up for many reasons. I am using a FT8900 with 50 watts out into a 1/4 wave or 1/2 Larson mobile antenna.The 1/4 wave is mounted permanently via a hole in the roof of my truck an the 1/2 wave is mounted on a mount opposite the factory installed FM/AM radio whip. It doesn't seem to matter what antenna I use for the problem to occur. Then I use either the arrow antenna or my cju for the downlink.

Use 5W into a hand-held Yagi.  You'll get far better results.

> Today I had another local ham over at the request of the neighbor and his mobile Kenwood radio did the same thing to the neighbors tv when he transmitted on 2 meter with 50 watts out. He also recommended that they get a filter. I did not see the specs on the filter nor do I know what bandwidth it was for. 

What you want is a highpass filter that will lop off everything below 500MHz.  The chances are that your TX output is clean enough but the little amplifier in the splitter for the TV is causing all sorts of intermod - and probably covers from broadcast VHF radio to the top of the TV band.

Gordon JC Pearce MM0YEQ <gordonjcp at gjcp.net>

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