We appreciate your comments regarding FCP construction Rick. We have Guy,
K2AV to thank - he is the developer, designer, engineer and I am fortunate
to be his Field Trial "Guinea Pig"
-----Original Message-----
From: Rick Karlquist [mailto:richard@karlquist.com]
Sent: Thursday, December 08, 2011 9:42 PM
To: W0UCE
Cc: topband@contesting.com; cwops@yahoogroups.com
Subject: Re: Topband: K2AV 160m Folded Counterpoise Antenna - New Details
Posted
W0UCE wrote:
> * The ONLY means of achieving the required degree of Isolation is to
> use the Isolation Transformer as specified by K2AV
> * Tests using 1:1 Baluns and Line Isolators have ALL FAILED - you
> waste RF Power, Time and Money unless the specified xfmr is installed
> * DO NOT attempt to use Insulated Window Line for the FCP - We already
> tried it and it does not work - too lossy
> * Use #12 Bare wire for the FCP elements - Moisture gathers on
> insulated wire and detunes the FCP
I haven't built this system, but the suggestions above make sense.
I have been trying to encourage using transformers instead of baluns
on 160 meters for years, but it's a tough sell to overcome the balun
habit. The tendency for loss in the open wire line also makes
sense. It is well known that window line is lossy when wet.
What is new here is that the Q is so high that you can't even
use insulated wire for open wire line. It would be interesting
to see if teflon insulated wire worked OK. The electric field
is maximum right at the conductor surface, so the insulation has
a considerable effect on characteristic impedance, thus I could
imagine it would affect loss too. I am feeding my vertical
using 850 feet of open wire line with XHHW insulation (whatever
that is made out of). It would be interesting to measure the
loss on a rainy day and see how much it increased. It's only
a few tenths of a dB when dry (the wires are 4 AWG aluminum).
Rick N6RK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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