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Asunto:[dxcolombia] RV: RFI Digest, Vol 42, Issue 5
Fecha:Jueves, 8 de Junio, 2006  12:12:21 (-0400)
Autor:Alexis Deniz M. 4M5DXgroup <yv5ssb @...net>



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-----Mensaje original-----
De: rfi-bounces@... [mailto:rfi-bounces@...] En nombre
de rfi-request@...
Enviado el: jueves, 08 de junio de 2006 12:00
Para: rfi@...
Asunto: RFI Digest, Vol 42, Issue 5

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Today's Topics:

   1. Re: Power line Noise (RFI Services)
   2. Re: Power line Noise (Jim Brown)
   3. Re: Power line Noise (RFI Services)
   4. Re: Power line Noise (Alan Robinson)


----------------------------------------------------------------------

Message: 1
Date: Wed, 7 Jun 2006 13:50:38 -0400
From: "RFI Services" <mike@...>
Subject: Re: [RFI] Power line Noise
To: "'Fred Stevens K2FRD'" <k2frd@...>, <rfi@...>
Message-ID: <003101c68a5a$e376a0d0$bc00000a@...>
Content-Type: text/plain; charset="us-ascii"

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@...
www.rfiservices.com


------------------------------

Message: 2
Date: Wed, 07 Jun 2006 14:02:06 -0700
From: "Jim Brown" <jim@...>
Subject: Re: [RFI] Power line Noise
To: "RFI List" <rfi@...>
Message-ID: <20060607210210.6A3785829C@gw1.nlenet.net>
Content-Type: text/plain; charset="us-ascii"

On Wed, 7 Jun 2006 13:50:38 -0400, RFI Services wrote:

>A Power line noise source will remain at a particular level. 

How does this relate to what I've heard about arcing at insulators 
due to humidity or corona discharge varying with weather conditions 
(which in some parts of the world vary with the time of day)?

Jim Brown K9YC 





------------------------------

Message: 3
Date: Wed, 7 Jun 2006 19:17:14 -0400
From: "RFI Services" <mike@...>
Subject: Re: [RFI] Power line Noise
To: "'Jim Brown'" <jim@...>,	"'RFI List'"
	<rfi@...>
Message-ID: <000601c68a88$836e5830$bc00000a@...>
Content-Type: text/plain;	charset="us-ascii"

Hi Jim and everyone,
RFI sources vary due to wind, rain, slight humidity and every other type of
weather condition. Humidity can short the gap containing the arc as well as
swell the wood construction causing the hardware to tighten. Also shorting
the gap.
As for corona, corona is highest during moist, humid and wet conditions.
However corona is rarely the cause of an RFI complaint. Example: When
walking down the street a couple blocks from the ocean front you'll hear
noise/ buzzing at every pole. This is due to tracking and corona. If you
monitor the same poles with an RF receiver, you'll notice very little if any
noise. The exception being if there is also a gap type noise source local to
your position. If this is the case, you'll notice the level change as you
get closer or further from the actual source being monitored. If corona was
a big issue for RFI complaints, hams couldn't operate close to transmission
circuits or coastal areas.
During my workshops I demo the effects of corona versus gap sparks. The
level of amazement is as interesting as that of the measurement of voltage
between a pole staple and the ground conductor.
Corona is often the blame but very rarely (less than 1%) the cause of RFI
complaints.

Remember, as the day progresses so does the sunshine.
Unless you know your RFI is active in the am, tell your power company RFI
Investigator to show up around 11am. 

And thanks Kelly,

RFI Services
Michael C Martin
6469 Old Solomons Island RD
Tracys Landing, MD 20779
240-508-3760
mike@...
www.rfiservices.com



------------------------------

Message: 4
Date: Wed, 7 Jun 2006 19:54:56 -0700
From: "Alan Robinson" <robinsah@...>
Subject: Re: [RFI] Power line Noise
To: <mike@...>, "'Fred Stevens K2FRD'" <k2frd@...>,
	<rfi@...>
Cc: w4lke@...
Message-ID: <001d01c68aa6$ed879dd0$6401a8c0@XP>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
	reply-type=original

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@...>
To: "'Fred Stevens K2FRD'" <k2frd@...>; <rfi@...>
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@...
> www.rfiservices.com
>
>


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----


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> RFI mailing list
> RFI@...
> http://lists.contesting.com/mailman/listinfo/rfi
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End of RFI Digest, Vol 42, Issue 5
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