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Local Noise on 2.4 GHZ

Most of the time the AO-40 S downlink is wiped out by
some kind of noise on the entire 2.4 GHZ  band here. 

I can't seem to locate the direction with the dish. It peaks
nearly at many different directions and occurs every
few KHZ across the band, with a VERY strong
signal at 2402.505. It may actually peak at another 
freq. outside of the ham band.

There are times when the noise
stops suddenly for a few minutes or more. It has a 
buzz like a sawtooth wave at about 120 HZ much like
power line noise. 

I have tried attenuating the signal to see if the receiver or
downconverter/pre amp is being overloaded. The noise still
can't be pinpointed in either plane.
The peaks are 20db over S9 and the valleys are about S9
when hunting it with the dish while listening to 2402.505
with no attenuation.

My dish is 60' from the house and up 30' above ground, so 
it should be out of the near field of any noise from the computer.
If it were coming from the computer, I should be able to point
the dish toward the house to peak the noise. It doesn't appear
to be coming from the house.

This may be something simple that I've overlooked, but it
is a problem when trying to work AO-40, causing lost QSO's
whenever the noise starts up.

I live in Dallas, TX and there are a LOT of RF sources here.

Can anyone tell me what this noise could be or how to pinpoint


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