[CQ-Contest] KT34XA Vs C3

[Dick Green]

Claudio,

I don't have experience with the KT34XA, but I have been able to compare the
C3E with both the TH-7 and a 4-el 20M monobander with 30' boom. I found the
C3E to be as good as or better than the TH-7 on 20M and 15M. The TH-7 was
slightly better on 10M, but not enough to justify the extra cost, weight and
windload of the TH-7. This is pretty amazing, when you consider that the
TH-7 boom is six feet longer than the C3E. I guess the trapless,
computer-modeled design must be the reason, or perhaps it's the TH-7's
complicated phasing tube matching system.

The big difference between the TH-7 and C3E is F/B ratio. The TH-7 F/B is
very high, probably at least 25-27dB. The C3E has relatively poor F/B, about
15dB. However, I don't always want steep F/B in a contest. Quite often I
work people off the back of the C3E that I would not be able to hear with
the TH-7.

Note that my TH-7 vs C3E results are about the same as the results in the
"HF Tribander Performance" report published by K7LXC and N0AX (they measured
the C3, not the C3E.) The report rates C3E at about .5dB better than the
TH-7 and about 1.4 dB worse than the original KT34XA (not the new design.)
The KT34XA F/B was not as steep as the TH-7, but somewhat better than the
C3.

The original KT34XA had mechanical problems that made it difficult to keep
in the air. Many people have had problems with performance and SWR on 15M. I
understand that the new model is much better designed. I don't know if they
have made any improvements to performance.

The 20M monobander is about 2.5dB better than the C3E, which is very close
to the published specs for the two antennas.

If you buy the Force-12 antenna, you should get the C3E. It has extra
elements that significantly improve 10M performance. The regular C3 gain on
10M is much lower than the KT34XA.

Hope this helps,
73, Dick WC1M


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