On Mon, 28 Sep 2009 16:41:58 -0400, Tommy wrote:
>pinions are just that. I totally disagree with both Jim and KXBill.
>I presently run some 600 foot of home made 4" spaced open wire to my wire
>20m yagi, and also to both of my 40m EDZ antennas. I just don't think 600'
>of 'black snake' would really be worthwhile?
WHOA Tommy! We're not disageeeing at all -- my comment was about 100 ft of
big coax to an 80M resonant dipole (0.6dB with 5:1 SWR), not 600 ft on 20M
(3.3dB matched). Those are VERY different engineering problems! Open wire
line IS probably the best solution for that. An EDZ on 40M is also a VERY
different problem -- the antenna is inherently a much higher impedance. At
the very least it would need a matching section to get it to coax.
The important thing is to approach every engineering problem with an open
mind, not a knee-jerk reaction or "one size fits all." At my QTH, I have
two 110 ft high 80/40 fan dipoles fed with about 150 ft of RG11 foam. Those
antennas work VERY well on 30M, 17M, and even 6M because 1) they're high;
2) I'm using low loss coax; 3) they're close to harmonic resonance on those
bands. They don't work well on 20 or 10, but I've got three very good
antennas for those bands. And all of those antennas are pretty quiet on RX
because I've got big coax ferrite chokes on them. (How well do they work on
6M? How about a dozen triple hop Es Qs from CA to W1, VE3, FL, and HI with
a barefoot K3? And I don't spend much time on 6M!)
73,
Jim Brown K9YC
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