[600MRG] Distance from powerline question

[Pat Hamel]

Has anyone considered the approach of a receiver in a quiet place securely
accessible from the internet? (Banyan-style access list + password required)
It might make QSOs easier for high-noise environments.

It would take someone younger than me to insure that the internet-connected
computer would not be "hackable" for someone to use as a relay to rob banks.
(A MicroVAX or other non-PC boat-anchor computer would stop the
script-kiddies).

Probably more than one receiver would be necessary, but there are ham
"remote stations" on the ham bands and we are not looking for DXCC
(yet).....
Just an idea,
Pat /6



-----Original Message-----
From: 600MRG [mailto:600mrg-bounces at w7ekb.com] On Behalf Of Rudy Severns
Sent: Monday, December 08, 2014 12:48 PM
To: Andy - KU4XR
Cc: 600MRG
Subject: Re: [600MRG] Distance from powerline question

My power line situation is pretty typical:  lines along the side of my 
property extending to and from infinity with periodic downleads for service 
to homes in the neighborhood.  Each service point has a ground wire from the

transformer to a ground stake at the base of the pole.  What I'm facing is 
an extensive array of vertical radiators with heavy top-loading.  The noise 
is coming at me over a wide arc.  Narrow directional nulling doesn't buy 
much!

For a short vertical the near E-field close to the radiator falls off as 
1/r^3.  In the case of 630m with 40'-50' high vertical radiators, the 
near-field extends out to at least 1/8-wave (250') and is still noticeable 
out to a 1/4-wave (500').  I have experimentally verified this using two 
identical vertical voltage probes, one 200' from the lines and the second 
another 200' away.  Doubling the distance from the source (200' to 400') you

would expect the induced voltage to decrease by a factor of 8 (2^3) or -18 
dB.  I measured -15 dB.

I've been busy playing receive antenna games here but what works best is to 
move the rx antenna as far as possible from the lines.  For me that's about 
400'.   For those of you in an urban environment that's probably not 
possible and there are no easy answers.

73, Rudy N6LF 



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