Here's the story. When I transmit a nice clean 200 watts CW on
14.060 MHz, I can hear a loud, buzzy, broad signal centered on
7.030, and I can also hear its third harmonic on 21.090. The
broad signal pretty much wipes out the 40 and 15 meter bands.
The noise, and the amount of RF power required to trigger it,
vary with the azimuth of my transmitting antenna, and point in
the direction of the house across the street. I am sure that
this signal is not coming from my radio equipment, or from my
house.
A friend walked over to the neighbor's house with a portable
shortwave receiver while I was transmitting, and the noise is
definitely coming from that house. He walked into the front
yard, and the noise peaked when he was directly beneath two
satellite dishes which are mounted on the roof. One is DISH TV
and the other is DirecTV. I plan to approach the residents
tomorrow to seek their cooperation. I suspect they have also
been having problems with the malfunctioning device. If they
cooperate, I plan to listen to the noise on the shortwave
receiver, and start turning off circuit breakers until the noise
goes away, and zero in on which device on the circuit is the
problem. If the breakers are labeled, I'll start with the room
that has the DirecTV and DISH receivers.
Has anyone encountered a situation like this, where a subharmonic
is being generated? I could use any other advice you can think
of. I am trying to do a multi-operator radio contest on
Thanksgiving weekend, so I would like to get this fixed as soon
as possible. I'll provide more info tomorrow, after I approach
the residents.
Dave Hachadorian, K6LL
Yuma, Arizona
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