[TenTec] Washing machine RFI - a problem solved

[Robert & Linda McGraw K4TAX]

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 at comcast.net>
To: "Discussion of Ten-Tec Equipment" <tentec at 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 at aol.com>
> To: "Discussion of Ten-Tec Equipment" <tentec at 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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>
>
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