Topband: strange QRM problem

[Ted Demopoulos <kt1v@demop.com>]

The new shack here has 3-way dimmer switches, i.e. the lights can be 
dimmed/undimmed from both in the shack and from the hallway leading 
there. There are almost no QRN issues with the dimmers, except on 
exactly one antenna, a beverage. The QRN used to be only heard  on 
topband, but also seems to affect 80m a bit. Its not too bad, maybe S1, 
but should be solvable somehow!

I have 3 sets of beverages and associated feedlines, and the noise only 
occurs on the 1100 foot NE Beverage, which incidentally happens to start 
the closest to the shack, about 150' away. I replaced all feedlines 
etc,  added about 20" of ferrites to the antenna end of the coax, with 
no change. This Beverage does have the worst feedpoint ground of them 
all as its in a rock field, but I do have 3 ground rods spaced roughly 
4-6 feet and in the ground from 2.5 to 5 feet deep. All Beverages (and 
other ants) come in thru the same aluminum feedthough panel.

I have two thoughts:
1)improve ground at Beverage (radials?)
2) The feedline, as its not cut to length, has a coil of maybe 100 feet 
of spare length next to the feedthrough panel and maybe 15 feet from the 
dimmer switches - could this be the culprit? (the previous feedline had 
a similar coil about 100' from the dimmer switches - as I'm hoping to 
move the Beverage further from the house).

Of course I could just get rid of the dimmer switches, but since only 
one antenna is affected, I may be treating the systmes instead of the 
problem by doing this??

73
Ted KT1V





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