I easily could have misread the original emailed problem, but he
included the note that this RFI occurred with all antennas [and I guess
other cables] disconnected which is very strange indeed. If that is so,
then I doubt stubs/filters on the antenna circuits would cure the problem.
His list of frequencies might suggest some sort of intermod between
constant signals, one being the FM carrier, and possibly their
harmonics. Very strange problem at any rate. FWIW, and Phil can
correct me, but US FM/TV stations are usually authorized in EIRP, I
think ... we referred to KSBY-TV, where I worked while in college, as
"Full-power television for the Central coast, one hundred thousand watts
on Channel 6 in San Luis Obispo" on ID's. That was EIRP, 10 KW to a 10
dB turnstile. If that's still true, it would seem a 2 KW EIRP FM
station 2 miles away shouldn't be a big deal.
73,
Fred K6DGW
- Northern California Contest Club
- CU in the Cal QSO Party 1-2 Oct 2016
- www.cqp.org
On 2/10/2016 2:04 PM, Ron D'Eau Claire wrote:
I agree. Even better.
73, Ron AC7AC
-----Original Message-----
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bob
McGraw K4TAX
Sent: Wednesday, February 10, 2016 9:18 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] 12 meter K3 RFI from nearby FM station
An electrical 1/4 wavelength of coax as an open stub at the FM frequency,
connected using a T at the receiver input, will notch the FM TX signal. It
won't attenuate other frequencies across the ham bands including 6M. Plus
one can transmit with the stub arrangement in place.
73
Bob, K4TAX
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