Hi Mike,
Good summary. Thanks for posting it. Here in Western Oregon, where it rains
a lot, then the sun shines, and then the wind blows, I have seen a few cases
where a single source has varied in intensity during the day. Also, we have
some intermittent sources that go on and off while you're standing there
listening with an ultrasonic (Radar Engineers Model 250).
In one case a set of hanging bells was going on and off while gusts of wind
shook them and the pole. As you know, the moister here has a big effect
during the day. As the wooden poles dry out the noise picks up, then later
as they cool in the high humidity the noise frequently quiets down some. In
some of these cases the sparking patterns hardly changes. Just the
intensity.
Anyway, thanks for your service to this reflector. I do appreciate reading
your postings. Also, I certainly enjoyed your great workshop. Very valuable.
73,
Alan, W4LKE
From: "RFI Services" <mike@rfiservices.com>
To: "'Fred Stevens K2FRD'" <k2frd@mac.com>; <rfi@contesting.com>
Sent: Wednesday, June 07, 2006 10:50 AM
Subject: Re: [RFI] Power line Noise
>A Power line noise source will remain at a particular level. The level of
> the source is determined by the actual hardware causing the arc and it's
> proximity to the voltage and neutral conductors that become the
> transmitting
> antenna for the noise. If the level is changing throughout the day, that
> is
> due to multiple sources. Some are stronger than others due to the above
> factors. Overall noise increases throughout the day because of the sun
> drying out the hardware creating more opportunity for gap sources.
> Power line sources radiate many frequencies at the source from below 1 meg
> to over 1000 and the higher frequancies weaken as you increase distance.
> However, this is effected by the physical position of your antenna as well
> as the sensitivity of the antenna at a particular band. If the source is
> weaker as you lower frequency, that could mean one of several things and
> not
> limited to or necessarily in this order:
>
> The lower freq antenna happens to be in a null portion of the wave
> length.
> If it were a little closer or a little further away from the source the
> results would be different.
> The antenna used on the lower freq is not as sensitive as the higher freq
> antenna being used.
> The noise source antenna (power co equipment) is more resonant at the
> higher freq. and close by.
> The source may not be power line.
>
> Regardless of the cause, the symptoms suggest it is not very far away and
> I
> would suggest you use my "How to locate instruction" before continuing.
>
> http://www.rfiservices.com/tips.htm
> http://www.rfiservices.com/residence.htm
>
> I would have responded sooner but for some reason I don't get most of the
> postings. Sometimes even my own.
>
> I hope this helps.
> Best wishes,
> RFI Services
> Michael C Martin
> 6469 Old Solomons Island RD
> Tracys Landing, MD 20779
> 240-508-3760
> mike@rfiservices.com
> www.rfiservices.com
>
>
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