In many cases, the issue is related to the specific installation or location
of the receiving antenna. If the feed-line is of poor integrity or the
antenna is in close proximity to the offending noise source it most likely
will be heard. In other cases where there is a good bit of distance the
offending noise is not a problem. Remember in terms of signal strengths, we
are dealing with the inverse square law here, so space makes for a big
difference.
Secondly, ground resistance on the AC neutral will also have bearing on the
matter. In a common mode noise condition, low resistance is important and
beware of ground loops on the AC neutral for they make great radiators. If
you don't believe it, ask anyone that uses a HF loop antenna for their
station.
Yes, your mileage will vary depending on you specific installation. The
best solution is to stop or trap the noise before it gets out of the
machine.
73
Bob, K4TAX
----- Original Message -----
From: "Dave W7DPW" <w7dpw@comcast.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Wednesday, September 28, 2005 8:38 PM
Subject: Re: [TenTec] Washing machine RFI - a problem solved
We recently purchased a new Neptune washer and have had it for several
weeks, I have noticed NO interferrence what so ever. I guess that I'll
have to make a further check and let the list know..
dave W7DPW
----- Original Message -----
From: "John Holliman" <w5ot@aol.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Wednesday, September 28, 2005 2:36 AM
Subject: [TenTec] Washing machine RFI - a problem solved
My wife's Neptune washer caused RFI every 17 Khz on most bands on my
Tentec Omni VI, and was especially bad on 20 and 17 meter bands. In
my
case, the RFI seems to be generated by the motor control circuit
during
certain parts of the wash cycle, and radiated by the house wiring
through the power cord. The solution was to use about $15 worth of
clip-on ferrites (material type 31) on the power cord itself and on
the
internal wiring connected to the power cord.
Suggestion: use a portable SW receiver as detector and start
experimenting with the ferrite filters. You will be able to hear your
progress. Note that some interference is radiated from the plastic
control panel cover, but that was negligible compared to the house
wiring in my case.
Good luck and good hunting,
73 de John, WA5TWL aka W5OT
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