On Mon, 1 Mar 2004 05:52:05 +0000 (UTC), "tedoboxer"
wrote:
Can you please advise on the optimal position for my atu. I'm a novice ham,
and at the moment I've got a random length of wire slung between my attic
roof and a garden tree (about 40 feet high), with a connection to the centre
wire of a 50 ohm coax cable as soon as it enters the attic roof, down to my
antenna tuner. My problem is a very high level of electrical noise across
most HF bands, especially the lower ones. We have a lot of electrical
cabling in the roof for lights, satellite tv etc, and switching them all off
would provoke a family riot. Would it be any better if the atu was between
the wire and the coax where it enters the roof (although it would be
difficult for me to get a power supply up there)? Any other possible
solutions to the noise problem? Thanks for your help.

Hi OM,

First, confirm your source of noise. During the wee hours, throw the
breaker to those electrical and electronics devices and see if the
noise goes away. No use in blaming the innocent. Use a battery
powered receiver if throwing the breaker also means killing your
shack.

Much of noise actually arrives through the Mains power connection
(typically a ground loop). If you can, move your rig's power to a
different breaker (break ALL grounds to do this, it may be more subtle
than you might imagine at first glance to do this). Dimmer noise (and
other sources) often is conducted through sharing a common breaker.

Radiative noise (not coming in through the mains, but over the air)
can be snubbed by using a choke at the coaxial far end (try moving
your feedpoint out and away from the attic, and placing a
choke/current BalUn on it).

73's
Richard Clark, KB7QHC