Thanks to all who responded on the KLM KT-34XA vs. the Hy-Gain TH7DX. There
were many responses, all informative. The consensus was... None! I got a
roughly equal number of responses in favor of each antenna. No one had
anything bad to say about the performance of either antenna. My general
feeling was that the KLM has the edge in forward gain and bandwidth, while
the TH7DX has the edge in F/B ratio, assembly and maintenance. No surprises
there; these characteristics are pretty evident from the specs.
I did get a couple of responses from people who moved from the TH7DX to the
KT-34XA and found the KLM's performance to be significantly better. I did
not receive responses from *anyone* who had a KT-34XA come down or get
mangled (although I did receive one response about how it stayed up in a
hurricane while a 40M beam came down!) I got some responses knocking the
maintainability of the KLM, but it was not clear that any of them were from
people who actually owned one.
I got a number of responses that lead me to believe that SWR on the TH7DX
won't be a big issue (they now have a low-phone setting that covers the CW
portion of the band better.) There were some significant differences in the
data I received, probably due to differences in the measuring equipment. I
saw some readings near the band edges that would make my amp start
worrying.
Bottom line, it sounds like the TH7DX is an all-around winner for balancing
performance with ease of assembly and maintenance. It's probably the best
tribander for contesters. However, I think the KT-34XA is probably the
better choice for someone like myself who has a touchy amp and whose top
priority is DXing (and will have a tilt-over tower...) The F/B ratio
difference bothers me a bit, but again, I think that's more of a problem
for contesting than DXing. Also, in looking closely at the Hy-Gain specs,
I'm not so sure it's a problem. Yes, KLM says 20 dB for the KT-34XA, while
Hy-Gain says 27 dB for the TH7DX. But they also say 27 dB for the TH5Mk2. I
happen to have a copy of the assembly manual for the TH5, and the detailed
specs there say f/b on 20M and 10M is 19 dB plus or minus 5 dB, and on 15M
it's 22 dB plus or minus 5 dB. The latter must be where the 27 dB comes
from. I assume it depends on how close to the resonant frequency you are
operating. I wonder if it's the same story with the TH7DX?
I personally don't care about the lengthy and complex assembly of the KLM,
because I'm hoping to do it only once. I like projects like that anyway.
Besides, it will give me something to do while I'm waiting three months or
more for U.S. Towers to deliver...
Speaking of which, see my next post, "The Moment of Truth"
73, Dick, WC1M
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