K0RC said:
"I am considering replacing [my] furnace.... There has been
advancements in technology in the past 17 years. This includes a
variable speed DC blower motor upgrade from a multi-speed AC motor.
Does anyone have any experience in the newer technologies in regard to
my HF gear? Specifically, a variable speed DC motor sounds like it
might be an RFI generator."
No experiece with the variable speed motor, but here is some related info.
I had a new furnace installed (10 ft behind my seat at the rig) about
a week before CQWW SSB. Coincidentally, I began to hear wide-band
splatter on modulation peaks from the 50KW AM station on 1500 KHz,
less than two miles from my house. The furnace is only middle-tech --
it has a selectable speed (rather than continuously variable) blower.
But it does, I'm sure, have a lot more electronics in its controller
than did the 27-year-old unit it replaced. I am suspicious that the
elex in the furnace is generating the QRM, but I have not tested the
hypothesis (have not even figured out how I could test). OTOH, I also
fear that the problem is in my TS-850 itself, because turning down the
RF gain or turning on the front-end attenuators seems to make the QRM
go away.
Also, the new furnace is much louder than the old one. It has
induction blowers and other air-moving stuff to make the combustion
more efficient. I might have to get new high-performance
noise-cancelling headphones. (I wonder if that cost would qualify for
the energy tax credit.)
73, Art K3KU
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