|To:||email@example.com, firstname.lastname@example.org, email@example.com,firstname.lastname@example.org|
|Subject:||Re: [TowerTalk] [RFI] 115 KV Lines|
|From:||"Pat Barthelow" <email@example.com>|
|Date:||Tue, 22 May 2007 08:19:14 -0700|
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 firstname.lastname@example.org http://www.jamesburgdish.org Jamesburg Earth Station Moon Bounce Team http://www.cq-vhf.com
From: kd4e <email@example.com>
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