I am relaying the event of my ham friend, Ken, W9IE, who has been plagued with
serious RFI spurs on all bands 20 meters and above. It bothered him for
several years. It made some frequencies on two meters unusable including
146.94 FM. It varied in frequency in that it slowly drifted across the FM
repeater channel. Using a portable receiver it was determined to be outside
his house (he did pull all the breakers in his house). Next suspect was the
Comcast distribution amplifier high on a pole outside his house. For some
reason he followed the cable drops radiating from the pole in each direction
using his radio to track the noise. One path took him to the next door
neighbor where the noise got quite loud. Ah ha…he says. The neighbor was
very cooperative and they systematically opened breakers in the power panel.
When they got to the family room the noise in the portable radio stopped.
Trouble was, there was little in the family room except reading lights. On a
hunch Ken asked what was on the other side of the wall. It turned out to be
the garage powered by the same circuit. A quick survey reveled a Hitachi 7.2
to 14 volt Ni-Cad/Ni-MH (model UC-14VFA) cordless drill battery charger that
was plugged in all the time. Testing showed RFI anytime the charger was
plugged in, battery or not caused serious RFI. Ken took his neighbor to a
local big box store and bought the him a new Dewalt cordless drill system. Ken
joked he was glad that the noise did not come from a washing machine or flat
screen TV. Neighbor rewarded for being cooperative and the was problem solved!
73, Brian W9HLQ
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