Hy Gain still uses the dual DE on their TH-7DX but not sure how many of
those they are selling these days with all the other choices out there.
73, Steve, WD8NPL
-----Original Message-----
From: Jim Thomson
Sent: Sunday, November 06, 2016 11:34 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Duo band 20/15 meter beam
Date: Sun, 6 Nov 2016 01:51:06 -0500
From: "Roger (K8RI) on TT" <K8RI-on-TowerTalk@tm.net>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Duo band 20/15 meter beam
The KLMs came out in the late 60s or early 70s. They worked well for
antennas of the day. I had 5L on 20 and 6L on 15. Mine "appeared" to
have gain, or were at least directive. IIRC they used dual DEs and were
quite broad banded. I had a 7L Wilson on 10 that played very well.
Even on that cycle low, I could hear JAs on an apparent dead band. It
was fed with a quasi air core coax. It had a spiral dielectric that
looked like layers of thin polystyrene. .They didn't use software as
there wasn't any except on mainframes and mini computers and it was
EXPENSIVE as was computer time. Programs, even at the college level
were input with punch cards.
73
Roger (K8RI)
## The dual de KLMs had a flat swr vs BW...but thats about it. The FB
vs
bw.... and gain vs bw was none too great. Most of those ants back then did
not hold
a good pattern across the band. These days nobody uses dual DEs, except on
40m,
like optibeam, jk, and m2. Even those, with their dual 40m DEs, dont hold
a
pattern across the band, only the swr is fairly low across the band.
## But still, the old yagis worked reasonably well.
Jim VE7RF
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