On Tue, 17 Jan 2006 01:20:34 GMT, jimg wrote:

jimg wrote:

ok, got me. to be accurate, eznec says the feedpoint Z is
32-j68.5...the apex is only 60' in the sky so the feedpoint impedance
is not too high. so that's where the 12:1 roughly came from (i was
playng with the height above ground).

so the question remains, ppl really run a very high swr at the
feedpoint..is there any advantage to matching at both point? i.e.
a fixed balanced impedance transformer up there at the feedpoint, and
then, of course, a tuner down here.

Jim, you can explore the options yourself. My transmission line
calculator at http://www.vk1od.net/tl/tllce.php will allow you to
specify the load impedance from your NEC model or transformer, and
calculate the losses on Wireman 55x ladder line.

For example, if you used 80' of 551 ladder line on 3.6MHz and the
feedpoint was 32-j70, the loss would be 0.5dB and the Z at the tx end
of the line would be around 380-j1200.

Owen

PS: I am a little surprised how low the R of you modelled feedpoint
is... I would have expected round 60 ohms, give or take.
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