I have some HV lines less than 100 yards from my antennas and in
general, the HV lines have always been quiet. The MV/LV residential
poles generate far more noise than the HV lines. The only exception
to this is when it rains. There is a very obvious rise in noise
levels whenever it rains. The noise goes away within about 30 minutes
after it stops raining. The noise seems to come from the HV lines. I
can tell by driving my car under the HV lines and the noise level goes
way up as I drive under them. Normally, the HV lines are quiet.
Fortunately for me, it doesn't rain all that often in California
otherwise I'd be miserable. The noise is quite unbearable while it
rains.
Is this a well known phenomena? Is it specific to HV lines? If so,
this may be something to consider if you get lots of rain in your
area.
On 5/22/07, Pat Barthelow <aa6eg@hotmail.com> wrote:
> Folks:
>
> Somewhere on the ARRL website is a downloadable CD file, that is the report
> of an Navy Postgrauate School Team, that for decades has studied and
> ameliorated HF and other RFI sources of noise, particlarly power line
> sources, that were of concern in Military applications. These guys are
> the best. The reports described the field procedures, and equipment
> selection that they used to find, characterize and ameliorate sources of RF
> noise, usually generated in AC power distribution systems. A couple of
> things stand out in my mind reading from their report, and hearing their
> talks at Ham Club meetings, and conferences.
>
> 1. High tension transmission lines (we are not talking about HV distribution
> lines) are rarely sources of RFI. I interpreted some of the follow up
> discussions on this by the experts, as saying that if there are insulator,
> or arcing and sparking problems in High tension lines, the consequencese
> are severely destructive and costly to the power companies, and the power
> companies fix and correct promptly else they lose equipment and dollars
>
> 2. Dirty insulator surfaces DO NOT cause HF interference to radio systems.
> Washing of such by the power companies temporarily reduces the RFI
> generation but the removal of contaminants on the ceramic insulator surface
> is not what is going on. The noise generation often sources from the
> (corroded) metal joints, the clevis pins, and interconnecting hardware,
> particularly so in the chain or stack, of ceramic disk types of insulators.
> The noise is ofen caused by repeated burn through, arcing on each rise and
> fall of the AC wave, between semiconducting/insulating corrosion layers in
> the metal fittings. The insulator washing detail, if it reduces noise, does
> so because the soaking of the hardware to a great degree makes the
> corrosion layers conductive, therefore there are less arcs and sparks
> between them. If you have a noise problem and it is suspected with good
> reason that a ceramic insulator chain is the problem, you can argue
> effectively a case for the power company to replace the old insulator(s)
> with a new type called, Epoxilators that are noise free.
>
> So, I dont think the 115KV lines are going to cause you any problems.
> The disk on the ARRL page is a great download and read.
>
> Sincerely, Pat Barthelow aa6eg@hotmail.com
> http://www.jamesburgdish.org
> Jamesburg Earth Station Moon Bounce Team
> http://www.cq-vhf.com
>
> >From: kd4e <kd4e@verizon.net>
> >Reply-To: kd4e@verizon.net
> >To: k4zw@comcast.net, rfi@contesting.com,TowerTalk
> ><towertalk@contesting.com>
> >Subject: Re: [TowerTalk] [RFI] 115 KV Lines
> >Date: Tue, 22 May 2007 09:24:37 -0400
> >
> >We are on an approx. 330' wide 1500' long 10ac lot.
> >
> >There are 45K lines up one side that are about 10yrs
> >old, they were in place when we bought the property.
> >
> >They are very quiet and the only hassle is one may
> >not erect anything permanent on that land and whatever
> >is there is subject to truck damage should they ever
> >need to service their wires.
> >
> >The only antenna hassle is that one should avoid any
> >long-wire antennas parallel to the lines.
> >
> >I wonder if the windmills may cause some flutter to
> >ground-wave signals from that direction the same as
> >airplanes sometimes do to TV signals?
> >
> >BTW: I copied this to the TowerTalk list as there
> >are some folks there who likely have good info for
> >you.
> >
> > > Wonder if anyone on the list has experience with nearby 115 KV
> > > transmission lines? I have a 43-acre property that I'm getting ready
> > > to develop, including an HF station. Last week I received a call
> > > from an engineering firm that is working on a wind generation farm on
> > > a nearby mountain. The problem, they want right of way permission to
> > > run the 115 KV transmission lines on my property either along the
> > > road or at the back of the lot. My first reaction was oh no! One of
> > > my office colleagues use to work for a power company in the Midwest.
> > > He suggested it might not be as bad as it sounds because 115 KV lines
> > > typically don't have transformers and lightning arrestors like you
> > > find in residential neighborhoods. Still, the thought of something
> > > like that nearby (within 200' – 2000' of my antennas) conjures up
> > > thoughts of potential RFI. I know I would not have bought the
> > > property had the lines been there to begin with. I realize there is
> > > no way to speak to the specifics of this case but what are your
> > > general experiences with lines like this and RFI? I haven't built on
> > > the lot yet but I was getting ready to put up the first two towers
> > > soon. Now I'm wondering whether I should proceed or ditch this
> > > location and look for another if they gain approval for right of way.
> > > It's a perfect location in all other respects so I really hate to
> > > bail. Any thoughts or experiences you can share would be greatly
> > > appreciated. Ken K4ZW
> >
> >--
> >
> >Thanks! & 73, doc, KD4E
> >Personal: http://bibleseven.com/kd4e.html
> >Ham QTH: http://bibleseven.com/steel/cjb-steelhouse-index.html
> >_______________________________________________
> >
> >
> >
> >_______________________________________________
> >TowerTalk mailing list
> >TowerTalk@contesting.com
> >http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|