Bob wrote:
Not too long for the info given! I am working on these exact things
courtesy of information passed to me by your friend Will. You didn't
know you were helping somebody in Syracuse, NY, but you have been.
Will has been kind enough to send me a lot of details on how you showed
him your "noise audit" procedure and ways to kill the noise. I just
received 20 of the Curtis filters from Hosfelt.
You helped Will and a bunch has "trickeled down" to me. Thank you very
much.

Bob

Glad to have helped. As people have helped me over the years,
I try to pass my bits of useful knowledge on to those who can
use them.

An often overlooked source of ferrite material is computer "stuff".

Keyboards, and mouses often have small ferrite beads inside.

VGA monitors often have big ferrite beads on the cable at the HD15
and right inside the monitor. They also often have other ferrite beads
inside and the better ones they have pretty good single stage RFI
filters on the power lead.

The switch mode power supplies have at least one, and often several,
ferrite toroids.

Even junk like VCRs and DVD players often have ferrite on the AC mains
and the PS unit often has ferrite cores.

Dead light dimmers are also good sources of ferrite torroids.

I have made it a point to scavenge every piece of ferrite I can lay my
hands on.

As W1HIS points out transmitting requires the selection of the correct
ferrite. But for receiving we want extra lossy ferrite. The lossier the
better.
Lossy ferrite wastes power by absorbing it and getting hot. And if your
receive ferrite gets hot you are too darn close to a MW power house!

Even iron dust cores do a suitable job of suppressing common mode
on coax, power lines and telephone lines.

And don't be saddened when you find the noise reduction process is
multi step. The first pass will get the big RFI sources, each succesive
pass will reduce the next level of RFI.

Another trick is to find some GE MOVs and disassemble them and add
a 1000pF cap across the hot to neutral and maybe hot to ground. And to
add a 1000pF across the light switches. This last step will stop, or
greatly
reduce the "pop" as lights are turned on or off. On unexpected
advantage
of adding MOVs across every circuit was the reduction of damage from
nearby lightning strikes.

You might find it usefull to make a sketch of your home showing every
outlet, switch and light fixture. Number them. Don't forget the smoke
alarm and door bell. Then number your circuit breakers and make a chart
showing which outlet is controlled by which breaker. Very handy when
non RFI troubles pop up.

Terry