On 9/2/2010 3:56 PM, mm wrote:
On Thu, 02 Sep 2010 13:38:16 -0500, The Daring Dufas
wrote:

On 9/2/2010 11:51 AM, mm wrote:
On Thu, 02 Sep 2010 07:56:08 -0400, Jeff
wrote:


Jeff
(used to hold a ham license, still remember something.... or part of
something!)

While we're talking about stuff like this.

Long ago when I was in high school I had a Hallicrafters reciever, 4
bands from ?? the table radio band up to shortwave.

And I was listening to the sound from one of the tv stations (even the
radio was AM and tv sound is supposed to be FM, but it matched the
sound coming from our tv on one channel) and every couple minutes I
would have to tune the radio higher. This went on for 40 minutes or
more, with me eventually tuning the radio much higher than it was, so
high I went off the end of the band.

I think there was a higher band so I started at the low end of that,
but couldn't find the same station.

What the heck was going on?

Could you have been picking up the IF harmonics from the TV itself?

Would the IF increase in frequency like that, maybe as the tv got
warmer. But before you answer look at my next answer.

Did your reception go away when the TV was off?

I think the tv wasn't on when I started. My older brother never
watched tv and I don't think my mother or I was until the signal
sounded like a tv show and I turned the tv on.

Maybe one of our next-door neigbhors' tvs? The lots were 100 feet
wide so his tv was 100 feet away more or less. The tv was in t he
middle of the house, about 40 feet from one property line and 60 feet
from the other.



Harmonic signals can be weird and caused by lots of unexpected things.
The Navy sometimes has problems when a bit of corrosion between two
pieces of metal turns into a semiconductor junction and because of
all the high power transmitters on board, that corroded metal can turn
into a transmitter when the RF from the intentional transmissions hit
it. I was repairing a two way radio some years ago when a transistor
exhibited some very odd characteristics. It would work fine for DC and
audio frequencies but when hit with RF it acted like an inductor and
caused interference on other radios. I replaced it with a new one and
the two way set worked fine. I've walked around transmitter sites with
a field strength meter plus portable receiver and seen some very strange
signals pop up when the transmitter was operating.

TDD