RadioBanter - View Single Post - How can I eliminate TV interference on shortwave?

October 15th 03, 06:59 AM

On 14 Oct 2003 21:18:24 -0700, (Robert Williams)
wrote:

When my neighbors turn their TVs on, I have to turn off my shortwave
radio because I get a terrible buzzing interference over most of the
shortwave band. I can't hear a thing. I also get a similar problem
when my wife turns on a florescent light in the kitchen. Is there
anyway to reduce or eliminate this kind of interference?

Rob KC7BUM
Portland, Oregon

Hi Rob,

There's one of two possibilities, and possibly both.

1. You need to make your antenna remote from living spaces and
connect to it with a choked coaxial transmission line. Choking can be
accomplished using 1:1 BalUns or simply winding 6 to 8 loops of line
in 6 to 8 inch loops near the antenna connection. This will aid in
over-the-air interference if that is the problem (TVs and lights don't
usually bother one beyond 20-40 feet).

2. You need to isolate your radio's power source from power lines
that have noise arriving from these TVs or lights. Sometimes this can
be accomplished by merely plugging into a different AC outlet, or a
different one in a different room. The plan here is to move away from
a breaker that has noisy electronics on it. This will aid in
conduction noise reduction which seems to be more likely, but odd that
neighbors are involved (unless you are in an apartment situation). An
even simpler test is to disconnect all ground connections (this comes
in through the outlet in one form or another) and running off battery
power. This means that the antenna connection has to be free of a
ground connection too (and no wall-warts charging your batteries while
trying this either, nor having your audio-out plugged into your home
entertainment system or hi-fi). This is a shared ground problem if it
is indeed the source of noise.

73's
Richard Clark, KB7QHC