On Thu, 27 Dec 2007 11:53:49 GMT, ml wrote:

I've been using a dipole antenna about 30ft each side connected to a
sgc tuner with about 5ft of ladderline . this is mounted on my roof's
elevator shack.

Hi Myles,

You first need to differentiate between radiated noise and conducted
noise - you obviously know where the source is.

To conducted noise:

Does the SGC share the same ground as the switching loads for the
elevator? If so, you want to find another ground. ANOTHER ground? A
jillion floors above earth? What does ground mean in that context?

The path for the motors' heavy current is through a wire. That wire
has resistance (however small). The current through that resistance
elevates "ground" above the normally placid and noiseless ground with
a hash of voltage noise that goes right into anything SHARING that
path (and also having alternative paths to the same ground - it is
quite common).

Finding another ground can be approached through two ways: randomly,
or analytically. Analytically can be masked by failures due to what
is perceived to be ground (that is how this all began). Randomly
dooms you to useless repetition in the guise of a new choice being a
different choice (often quite rare). Random has the benefit of being
quick and luck may come your way suddenly (it can also vanish just as
fast when something changes - this how all this began).

Analytically: Where do you ground things on top of the elevator shed?
Move that to wire it to a more remote point. If you don't ground
anywhere on the roof, then we move on:

To consider radiated noise:

This is the same noise being coupled through the air. If you don't
ground at the roof, then you might have long conductors that run in
close proximity to the heavy current burdened wires of the motors. If
so, then you will want to choke your wires going down to your shack.
ALL OF THE WIRES GOING TO YOUR SHACK. You may need to do this
repeatedly along their length. You are going to get an education in
Ferrites if this proves to be the solution.

As an aside:
the new stuff i ckt
boards inside of metal boxes
If you can, closely examine those boxes to see if they have a separate
ground wire. Follow it where ever it might go. This might identify a
quiet ground, or a noisy ground point for you to try to tie into as
part of your experimentation. Similarly, If you can, closely examine
those motors to see if they have a separate ground wire. See if they
go anywhere you can use, or avoid as the conditions of experimentation
reveals.

73's
Richard Clark, KB7QHC