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Re: [RFI] Interesting Noise

To: <Jimk8mr@aol.com>, <rfi@contesting.com>
Subject: Re: [RFI] Interesting Noise
From: Doug Rehman <doug@k4ac.com>
Date: Fri, 11 Mar 2011 08:40:49 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
The noise sounded like typical power line noise, not white noise.


The halo is about 75'. The tower lights (24 VDC) are about 18" higher and
there are several vertically polarized antennas on the 10' of mast above the





From: Jimk8mr@aol.com [mailto:Jimk8mr@aol.com] 
Sent: Thursday, March 10, 2011 10:47 PM
To: k4ac; rfi@contesting.com
Subject: Re: [RFI] Interesting Noise


Tell us more about the noise:  does it have a buzz to it (60/120 Hz), or is
it white noise?


If the former, some sort of power line related noise.  Hard to troubleshoot
if it only shows up once every two years for a few minutes.


If it is white noise, it is likely precipitation static, which is not
affected or controlled by surge suppressors. DC grounding is likewise not a
preventative measure, since it is grounding at the RF frequency that would


It is common for precipitation static to be worst in the first few minutes
of a storm, even though the precipitation continues on for a while.


How high is the antenna? Generally the higher it is, the more prone to
precipitation static.  In the case of large stacked HF yagis, it is common
for the top one to be affected by precipitation static, while the lower one
isn't. (This is also a matter of a sort of shielding of the lower antenna by
the higher one).



73  -  Jim   K8MR



In a message dated 3/10/2011 10:05:55 P.M. Eastern Standard Time,
doug@k4ac.com writes:

I've received several emails indicating rain/precipitation static. I don't
think so as:

1) the antenna it was connected to is at DC ground (halo loop)

2) there is a surge suppressor in the outside connect panel

3) there's another surge suppressor at the input to the radio

4) I've been in Florida for a lot of years and this is the first time I've
ever heard anything like this on 2 meters. It sounded very much like line
noise (which I've spent the better part of a year working with the local
power company to eliminate).

5) although the rain continued at a heavy rate for about an hour, the noise
only lasted a few minutes (never had this happen before either)


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