micky wrote in
:

On Mon, 19 Nov 2012 04:47:24 +0000 (UTC), gregz
wrote:

micky wrote:
Interference with FM radio, goes away when my hand is near.

In the last six months I've had interference with two FM radio
stations. I thought FM was immune to most interference?? So
what might be doing it?

It's so loud I can't hear the program,. But when I hold my fist
very near the radio or touching the front, the noise goes away
gradually and then completely when my hand is close enough. Is
there some way to duplicate the effect of my hand being near the
radio??????? I tried a lot of things in a very different stituation
and nothing I tried worked.

Details.
It only happens sometimes, often in the middle of the night, and
when it's on one radio it's on two others also. Two have digital
tuning and one, maybe two, have analog (One digital is expensive
25 y.o, the other maybe 10, one analog is transistor 40 y.o. or so.
All of them work well otherwise.) It often lasts only 15 minutes
or less, sometimes with interruptions with no noise. It may last
longer other times but I don't have the patience to keep checking.
When I find my mp3 player with FM radio, I'm going to walk around
the n'hood and see if I can find the source.

There's a bus with a 2-way radio that parks less than 100 yards from
my bedroom, but the noise occurs even when it's not thjre. My
n'bors all seem to keep regular hours, not up in the middle of the
night, and none have SWave antennas visible, and the noise has no
words.

I live in Baltimore and it occurs on 88.5 and 90.1 MHz. FWIW these
are both DC stations 30 or 40 miles away, NPR and C-SPAN raido..
88.1 which is local never gets interference. I don't know where
other stations on the dial are,located sine these are the only 3 I
listen to.

It sounds like a foghorn, a consistent deep (loud) tone, but a
little higher pitch than a real foghorn. .

Thanks.

If it is in your residence, shut off the breaker to see if it stops on
the portable.

Greg

Thanks. I will try that. but it's pretty quiet here in the middle of
the night**

Anyone have any idea how to duplicate the effect of my fist or hand
near the radio? That gets rid of the noise. I'm lying on a sheet
and mattress -- I don't think I'm grounded. A bag hung in front of
the radio filled with cooked chicken? Raw chicken? Metal scraps? I
can try the last one, but I'm not made of metal. Paperback books?

** only the furnace, fridge, and one outdoor IR triggered light. None
of them go on for a minute then off for a minute and back on. I can
tell t he furnace is not on all the time because the hot air vent is
right near me when the I'm in bed.



Your arm acts as an additional antenna, capacitively coupled.
This suggests that the orientation and/or antenna size is
bad for your location.
Attach a wire of about 2 meter to the antenna, and play with
the orientation.
Even better is to find the interference source, any modern switching
supply(computer, charger,GFL light,new fl light,senseo coffee) is a prime
candidate, even if you think the divice is switched off,
a lot of them still have an active computer chip and supply inside.