[RFI] Unusual subharmonic RFI

[Dave Hachadorian]

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