Given the region of the country where you live, and given the on/off cycle
intervals you've indicated, I'd be inclined to suspect the electronic circuitry
for the variable speed blower fan in the air handler of a newer, high
efficiency air conditioning system in someone's house to the SW of you.
What I don't know, however, is what happens with the A/C blower fan in a modern
heat pump system during cold weather. (Thirty years ago, I had a heat pump
system that used auxiliary resistance coils to provide heat, and the air was
circulated somewhat differently in the winter than it was during the summer.)
Thus, given the season (it was -27 F here this morning!), I'm also inclined to
include among the list of suspects a controller for an electric blanket or
electric mattress pad. Does it ever turn off for extended periods (such as
during the day)?
I'm told, but have no first-hand experience, that the new tankless, instant hot
water heaters really put out a racket, too. Whether the cycle times you have
measured are consistent with those devices or not, I have no idea.
On Jan 24, 2011, at 9:14 AM, K4RO Kirk Pickering wrote:
> I have been plagued recently by a noise source which is
> wiping out signals on the 160m and 80m bands. It is 20dB
> louder on my SW Beverage than any other direction.
> The noise is intermittent, and comes on for roughly 10-15
> minute intervals, and when it goes off, it is completely
> quiet for another roughly 10 minutes. The amplitude peaks
> are at approximately 20-30 kHz intervals, an seem to vary
> somewhat. with frequency. I can hear the noise from about
> 1600 to 4200 khz. It's really hurting my 80 and 160 meter
> reception. Here is what the noise sounded like this morning:
> Before I start hunting, I wonder if anyone has heard this
> type of noise before, and might be able to identify it?
> Thanks for any suggestions.
> Kirk K4RO
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