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Re: [TowerTalk] Corona Electromagnetic Interference

To: "TOWERTALK@contesting. com" <TOWERTALK@contesting.com>
Subject: Re: [TowerTalk] Corona Electromagnetic Interference
From: Don Moman VE6JY <ve6jy.1@gmail.com>
Date: Mon, 25 Apr 2011 04:05:14 +0000
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
This is just plain old precipitation static - we experience that probably 50
times a year. Exactly as you describe.  Tom covers the subject very well in
his site: http://www.w8ji.com/pecipitation_static.htm

<http://www.w8ji.com/pecipitation_static.htm>73 Don
VE6JY

On Mon, Apr 25, 2011 at 3:58 AM, Kipton Moravec <kip@kdream.com> wrote:

> On Sun, 2011-04-24 at 19:42 -0500, Barry Merrill, W5GN wrote:
> > I'm really confused.   This is an FM repeater, so the noise is capturing
> the
> > receiver,
> > turning on the repeater, and you hear all the noise, only when it's
> raining?
>
> No. The nois is bad when someone wants to use the repeater. Mobile
> stations as so noisy they are hard to understand. One of the NCS usually
> has full quieting at 25W had to go to 75W to be understood.
>
> When there are not storms nearby everything is fine, and we get 50-60
> mile range to mobile stations. It goes away quickly when the storms
> pass.  The storm may or may not have rain at the repeater.
>
> We do not think it is a moisture problem because it clears up before
> things have a chance to dry up.
>
>
> >
> > Or, the noise never captures the receiver you only hear noise when a
> station
> > has
> > captured the rf and turned on the repeater and then you hear lots of
> noise?
>
> Yes.
>
> >
> > I know from submerged operations from Navy Submarines that if this were
> 10
> > meters
> > SSB or CW, it sounds like rain static and you only need a high ohm
> resistor
> > from the antenna to ground.
> >
> > Barry, W5GN
>
> That is what I am wondering about. Using a 1M to 10M resistor from the
> center conductor to the ground, to bleed off any static. That high of a
> resistance would not affect operation.
>
> Kip
>
> >
> > -----Original Message-----
> > From: towertalk-bounces@contesting.com
> > [mailto:towertalk-bounces@contesting.com] On Behalf Of Kipton Moravec
> > Sent: Sunday, April 24, 2011 6:27 PM
> > To: Fuqua, Bill L
> > Cc: towertalk@contesting.com
> > Subject: Re: [TowerTalk] Corona Electromagnetic Interference
> >
> > On Sun, 2011-04-24 at 01:59 -0400, Fuqua, Bill L wrote:
> > > If you have not had a problem in 4 years and now you do you may look
> into
> > other electrical hardware on the tower.
> > > It may me lighting systems that have started to arc when there is
> > > heavy rain or some other electrical problems caused by rain or wind.
> > > If it is particularly cold it could be ice on the antenna which detunes
> > it. Water has a very high dielectric constant.
> > > Unlikely corona.
> > >
> > > 73
> > > bill wa4lav
> > >
> >
> > When we inspected the system yesterday, we noticed none of the antennas
> were
> > properly grounded to the tower where they clamped onto the upright of the
> > railing around the top of the tower.
> >
> > The railing has a heavy coat of paint, and I guess that we assumed that
> the
> > U-Bolts would crush the paint and make contact. If they do not then that
> is
> > like a capacitor. In the next couple of weeks we are going back and
> adding a
> > short #8 or #10 ground wire from the antenna to a self-tapping screw into
> > the post where we are certain we will be making good electrical contact.
> >
> > We have lightning arrestors where the coax goes into the the tower, and
> > there is a big copper grounding plate.
> >
> > About halfway down there is a grounding strap from the coax shield to one
> of
> > the water tank ground wires.
> >
> > At the bottom, the coax shield is grounded again to a big single point
> > ground near the repeater cabinets.
> >
> > So we have identified one potential problem area. But it still baffles me
> > why we have not had a problem until this spring. And it is bad when a
> storm
> > comes through and clears up quickly when it passes. Not very good for a
> > Skywarn repeater. But that tells us that it is not a moisture problem,
> > because it would take a long time to dry out. That is not the case.
> >
> > Our "lightning arrestor" experts tell us that the lightning arrestor will
> > fail in a short between the center and coax shield, so it is not the
> > lightning arrestor. That seems a little odd to me, but he works on
> > commercial antenna sites as his job, and is very knowledgeable. So I have
> to
> > believe he knows what he is talking about.
> >
> > We are in North Texas, and do not currently have any ice to worry about.
> > We do get ice storms for a couple of days in the year, but not now.
> >
> > Thanks for the suggestions everybody.
> >
> > Kip
> > --
> > Kipton Moravec AE5IB .- . ..... .. -...
> >
> > "Always do right; this will gratify some people and astonish the rest."
> > --Mark Twain
> >
> >
> > _______________________________________________
> >
> >
> >
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> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
> >
>
>
> --
> Kipton Moravec AE5IB .- . ..... .. -...
>
> "Always do right; this will gratify some people and astonish the rest."
> --Mark Twain
>
>
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