Did my note about using a 1/4 wl open-ended stub make it onto the reflector?
I was receiving MAJOR interference from a CB station about 1/4 mile from my
10 meter repeater. This guy interferes with telephones and tv's all over his
subdivision, and the repeater receive site was within view of his tower. He
would desense the repeater so badly tham most everyone was unable to access
it when he was active (and he's VERY active!). His AM signal was also being
rectified everywhere in the system. He openly admited to operating at 1kw+,
and made it clear at the time that he was there before the repeater site,
Sooo...I tried a lot of stuff from shielding to building a 10 meter notch
cavity (which was too narrow to notch the whole CB band...), and found that
a 1/4 wl stub worked. The stub was about 500 khz wide @ 30ish db down and
had wide skirts.
Shortly after that, a CB station came on the air in my subdivision. Lots of
trash that blocked my RX's from 20m through 6m with everything from music to
creative profanity. The stubs worked in my shack very nicely, and I only
have a minimal amount of interference on the lower part of 10 meters.
73 de Dave Hockaday WB4IUY
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