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[RFI] RFI on TV while using dummy load

To: <rfi@contesting.com>
Subject: [RFI] RFI on TV while using dummy load
From: k6ll@juno.com (k6ll@juno.com)
Date: Mon, 14 Feb 2000 23:24:01 -0700

On Mon, 14 Feb 2000 17:05:36 -0600 dj2001@isd.net writes:
> I wonder if anyone has a idea on this one.
> TVI into the vidio of a TV set which is hooked up to a dish 
> (EchoStar 
> dbs system) transmitter on 15 meter band while transmitting into a 
> dummy load, the worst seems to center on 21.158, and gets better as 
> I 
> move up the band.  RF output 200 watts.

If the Echostar output to the tv is on channel 3, it's probably
the third harmonic of 21mhz getting into channel 3.

You could try a lowpass filter on the tx. Some of those dummy loads
are pretty leaky. A line filter on the tx may help. A good ground
on the tx may also help. If the dummy load is REALLY leaky, the
tv could be overloading and generating its own harmonics on channel 3.
In that case, the 21 mhz rf is probably on the outside of the tv coax,
and a big type 43 toroid with as many turns of RG-6 as will fit onto it 
can be placed at the tv input.

You could also sidestep the whole issue by doing one of the following.
You could switch the satellite unit to output to the tv on channel 4.
You could use direct audio and video connections to the tv, if the
tv has such provisions. You could also use an s-video connection from
the satellite to the tv, if the tv is so equipped.

Dave Hachadorian, K6LL
Yuma, AZ

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