[UK-CONTEST] Long Distance Feedlines

[Adrian Rees (MW1LCR)]

Hi Chris, all
Well I have seen the ZL6QH website, and noted the baluns used to match
the feeders. These seem to be quite typical Guanella Baluns, at 8:1 to
match 50 Ohm Coax feeder, although I am somewhat puzzled by the
capacitors...(I'll need to think about that one on the way to work
tomorrow).

I have plenty of 450 Ohm open wire feeder, and can easily get it 6 to 8
Foot above ground and insulated. Browsing the Amidon website, I will use
T-400A or T-200 cores for the Baluns.

Only question is, how high off the ground does the open wire feeder need
to be ? I thought only 3 or 4 feet, but the  boys at ZL6QH are using
telegraph poles..... Or is this just safety ? 

TIA

Adrian



-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com] On Behalf Of Chris Tran
Sent: 25 September 2006 18:38
To: uk-contest at contesting.com
Subject: Re: [UK-CONTEST] Long Distance Feedlines


Hi Adrian et al

The set-up you describe is used at ZL6QH - see www.zl6qh.com    The 
open-wire feeders are approximately 400 ohm - 12-14swg wire space about
12 
inches apart - at the TX end there are 1:9 baluns fed with RG213 from
the 
shack, but at the antenna end the open-wire feedline is connected
directly 
to the antenna.  Even the 2 x 10m, 1 x 15m and 1 x 20m yagis are fed in
this 
way, because they are fixed yagis so there are no mechanical rotation 
considerations with open-wire feed. I think the 1:9 ferrite baluns are 
described somewhere on the ZL6QH website.

This system seems reasonably efficient - there are no coax-fed reference

antennas to do any real comparisons, but results are good. The open-wire

feedlines are anywhere between 10 and 15 feet above ground - the longest
run 
is about 300m similar to your proposed set-up.

I would think that your main considerations will be the mechanical
mounting 
of the feedlines - you need about 15-20 old telephone poles, complete
with 
insulators !

73
Chris
GM3WOJ 

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