E Z Peaces wrote:
Jeff Wisnia wrote:
The Daring Dufas wrote:


I had a friend some years ago who ran the communications
division of the local power company. This was back when
they had HF radios for communications and the techs actually
had to know something about electronics. They would get
electronic interference complaints which were often traced
to doorbell transformers. It was a very common problem and
one that many people don't even think of today.

TDD


Sorry, but I have a hard time believing that.

If it was "a very common problem", can you offer a cite proving that a
60 hz transformer and 10-50 feet of unshielded wire with 24 vac on it
can cause interference at radio frequencies?

Wouldn't you expect that if that story was true those big pole pig
transformers and all that higher voltage wiring running on the poles
on nearly every street would have caused the radios to melt? G

Jeff


According to the FCC Interference Handbook, defective doorbell
transformers are often a source of interference to TVs and other
household electronics. It may be a neighbor's transformer. I think it
happens when part of the core comes loose and vibrates.

I'm no EE, but I would guess that most of the in-house interference is
back down along the power lines, not through the air. I know that on the
baby shortwave I use to AM-band DX myself to sleep at night, when some
unknown something in my house (or one of the neighbor's houses on the
same pole can) is running, I can't get S**t to come in. But if I unplug
the wall wart and run on batteries it comes in fine, as long as the
unplugged cord is over a foot from the radio. Intermittent as hell, and
annoying.

--
aem sends...