On 01/17/2011 05:50 AM, D. Peter Maus wrote:
On 1/16/11 19:14 , bpnjensen wrote:


Your wire is likely pulling noise out of your house. If you can't move
the wire away from the house, then you do have a bit of a challenge. And
isolator will only produce a cleaner path for the radiated noise picked
up by your antenna to follow to your receiver.

That said, the isolator you're looking at is far more expense than
performance for your application. You can do as much with a 9:1
transformer, either prepackaged from Mini-Circuits, or home made by
winding around an Amidon toroid worked against an earth ground. Or you
could pickup the RF Systems Magnetic Longwire Balun. Also more expense
than you need, but it's a good match for what you're trying to achieve,
and durable in construction if you're not comfortable growing your own.
Anything you want to do, though, will require a good earth ground.

Something like the Wellbrook Loop would also be a good choice. Costly,
of course. Solid performance, though. And unobtrusive. Or, if you can
get away with it, an RF Systems MTA. Now, I have one, and I use it
regularly. In a high noise environment, it's very effective. But, man
made noise, radiated from the electronics and other appliances in the
home...it's not so effective against that. MTA, like the Wellbrook, or
the isolation systems you're considering, will be most effective against
high levels of atmospheric noise. Less so with man made noise radiated
into your antenna space.


Have you tried clamp-on ferrite beads on your AC Mains, right at the
meter? They have to be the right ferrite mix for low HF and you may need
to use more than 1 per leg. That will get all the dimmer buzz and
switchmode whistles from the power lines off your home AC.

I can vouch for these two papers as being very informative without
getting too academic:

http://www.audiosystemsgroup.com/RFI-Ham.pdf

http://www.audiosystemsgroup.com/SAC0305Ferrites.pdf