The first thing to determine is whether the shack outlets are on the
same side of the line or the same branch circuit as the washer!
VSD motor circuits are elegant for what they do, but they distort the
sine wave cycle in such a way as to create RFI. We have such circuits
added to our big air conditioning fan rooms at work and ever since, we
have had higher RFI to experiments in the lab. You can walk down the
hall next to the fan room and pick up the hash on a portable radio.
Everything is grounded and wired to code and such, just the nature of
the way they vary AC motors electronically.
Of course in the home it is always good to check your outlets with a 3
wire tester to make sure neutral and green are where they should be, as
well as the hot wire. Everything in the shack should connect to one
branch circuit to avoid loop problems.
Depending on whether the hash is conducting along the green wire, or
others, you might cure it by running the rig on an isolation transformer.
However, I think it was said another rig does not respond on that same
circuit? Look to see if Drake had a filter on the AC line, or what is
different between the power wiring of the two. Don't overlook issues of
if DC wiring from a remote power supply is twisted or not, how close one
rig was to the washer as compared to the placement of the other one, etc.
Sometimes placement of a transformer power supply close to a wall
carrying romex for the offending circuit may allow RFI to be picked up
whereas, moving the power supply twice as far from the wall might
attenuate it enough.
ARRL has a book on chasing RFI problems, which helps you organize your
search and look for things we all forget to check.
Good luck on finding an easy fix for the problem, (one short of sending
out the laundry).
-Stuart Rohre
K5KVH
|