[RFI] RFI from HIGH voltage power lines

[Jeff Blaine]

Related question.

I'm looking to move to a place where I can put up a decent spread of 
antennas.  A couple of the places have been scratched because the high 
tension lines were within 1000' or so of the potential QTH.

This thread got me to thinking - can one assume a rough rule of thumb on 
distance to big lines?

I realize the inverse square rule applies to any RFI problem that exists. 
Which argues a diminishing return in spacing - and concludes the further the 
better.

On the other hand, I would guess the power companies would tend to want to 
fix any little thing found on the bigger lines because leakage or whatever 
on these big boys spells many problems for them.  So it may not be as big of 
an issue as what one would assume?

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-----Original Message----- 
From: K1TTT
Sent: Friday, June 01, 2012 8:53 AM
To: 'RFI Reflector'
Subject: Re: [RFI] RFI from HIGH voltage power lines

The 'beads' or 'bells' as they are usually called on the insulator strings
are the key.  As a rough guess you can assume 20-25kv line voltage for each
glass or ceramic insulator bell in the string.  So 10 of them would give
200-250kv, the common voltage used in that range in the states is 230kv.  If
the line is well maintained it should not generate much interference, but
you must remember that it is allowed to generate a little bit, so close to
the line won't be as quiet as farther away.  If you can take a mobile
station there during different weather conditions you could get an idea
about how noisy the line might be.

And yes, the 2 wires above the 3 heavy current carrying ones are for
lightning protection.

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net


-----Original Message-----
From: Jim Miller KG0KP [mailto:JimMiller at STL-OnLine.Net]
Sent: Friday, June 01, 2012 11:30
To: RFI Reflector
Subject: [RFI] RFI from HIGH voltage power lines

Just wondering....   I have a few acres that run along HIGH power lines and
wonder if it is even worth considering building a small weekend
place/hamshack there.  The antennas would likely be between 100 to not more
than 250 feet from these guys.

My question is whether RFI is more likely to be generated by these guys
verses the smaller distribution lines along the average two lane blacktop
rural road.

These lines are the big guys.  If any of this helps to identify the amount
of power, here it is.  Probably a quarter mile of more average between
supports that are three poles each.  Height is estimated maybe about 40 feet
to the lines.  There are three lines and the outside lines of the three are
about 31 feet apart.  There are 10 "beads" or "cones" making up each of the
insulators the wires are hanging on.  There are two cables running above the
power lines (maybe for lightning to strike them instead of the power lines
themselves?).  Anybody have any idea of the voltage these would be carrying?

Thanks es 73, de Jim KG0KP



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