"ml" wrote in message
...
hi

was trying to build a loop antenna i can use to hunt down some
interference


snip


thanks wasn't sure how to figure it out but i have to hunt down the
interference as it's accross 1-30mhz and s9

Not a direct answer to your question, but practical guidance, I hope, since
the interference is heard down to 1 MHz, in the AM broadcast band (approx.
0.520 - 1.710 MHz):

Most AM radios receive best when the antenna is aligned broadside to the
signal arrival. They exhibit sharp signal dropouts or "nulls" when their
built-in rod antennas are aligned with the signal arrival.

Try this: Tune an AM station and slowly rotate the radio. (It's probably
better to use a battery powered radio.) You should hear two distinct
nulls -- first in one position and again when the radio has been turned a
half circle further. You may need to turn the radio on its back or side to
hear the most obvious nulls as you rotate it.

Next, if you know where the transmitter is
[http://www.fcc.gov/mb/audio/amq.html] you can relate its location to how
the radio is positioned when you null that station.

So, you have a simple DF set. Now, tune *off* the station into a dead freq
and try the same thing on the sound of the interference, trying for that
null. Although you'll have two possible directions for the source, changing
your location within the house should allow you to triangulate the source.
You might need to go outside.

Caution: if it's getting on the power lines, it can drive you bats; One
approach is to walk around with the radio and place it near plugged-in
items -- even if you think they're off*. The buzz may get louder and softer
as you move around, revealing the source.

A/C adapters and battery chargers are possible sources of such interference,
as are dimmers and some computer monitors, although monitors tend to put out
a "comb" of frequencies -- clear/noisy/clear/noisy as you tune the band.
Put aquarium heaters, electric blankets, baby monitors and garage door
openers on the list of suspects. Many electrical or electronic devices have
circuitry in them which could cause what you describe.

*My friend's VCR, even powered down, caused interference to his HF
reception. Because the VCR has a clock/timer that runs all the time, his
only solution was to unplug it when he wasn't using it.