I'll add a few stories from my RFI experiences. The first one was a problem
with a very wide band pulsing noise that suddenly appeared that I tracked to my
neighbor's house about 100 yards away. Could hear it from 15M all the way up
through UHF. Very cooperative neighbor who actually put the whole story on
YouTube at https://www.youtube.com/watch?v=HaX9mi3FAvM Culprit was a thermal
protector in a recessed lightning fixture. I still have the fixture plus
thermal protector but could not get it to repeat on the bench. The mechanical
shock of removing the fixture must had disturbed the device, but it was still
bad since any light placed in it would turn off after a minute or so with no
extra heat applied to the thermal protector.
The second case was many years ago when the local radio club received a request
fro help from a fellow who said he and his neighbors had bad TV interference.
I went to the guy's house but of course there was no interference that day. I
looked at his setup. A chimney mounted Yagi with a preamp, coax in
questionable condition and numerous spltters and amplifiers in the house. I
asked him to make a video tape next time he had the interference. A few days
later he called me. The tape clearly showed strong TVI banding across his
screen. I suggested that the next time he had the interference, he use his TV
rotor to aim the antenna to get the most interference so we could begin to
track the source. But I added a little white lie ...I told him he had to
remove the preamp up at the TV antenna and run new coax straight to his TV,
otherwise the Yagi would not have any directivity. After a few weeks I called
him and he said the interference had gone away so he was not able to find th
e direction of the source. I then explained to him that the likely cause was
his antenna-mounted preamp going into oscillation and becoming the source of
his interference. He sheepishly then told me his neighbors had become
disgusted and had just switched to cable TV.
N3AE
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