Hi Tony -- As always, I find your stuff sensible and thought-inducing. But
the one place I don't agree with you is on the *magnitude* of the gain
advantage enjoyed by the KT-34XA.
At 04:15 PM 1/14/97 -0500, you wrote:
(stuff deleted)
>3. As far as Force12 advertising claims, I'm skeptical. First, comparing
>a C3 to a KT34XA, the XA is really 4 elements on 15 and 20, and 5-6 elements
>on 20 [sic - think you meant 10]. If you check with the experts, or do some
modelling, >you'll find that the XA comes out 4-8 dB better in the forward
gain department.
(more deleted)
According to my modeling (all antennas at 97 feet):
20 M C-3 TH-7
Net Gain* 5.0 dB 5.5 dB
F/B 10 dB 18 dB
15 M
Net Gain 4.75 dB 5.75 dB
F/B 12 dB 24 dB
*Obtained by subtracting 7.5(20m) or 8(15m)dB from the dBi figures that
EZNEC produces, the approximate ground reflection gain of a dipole at this
height.
So you're saying that the XA beats the C-3 (or the TH-7) in forward gain by
more than a TH-7 beats a dipole at the same height. I don't buy it. 2-3 dB
over the C-3 would seem more reasonable.
As I told Pete, there's no way I'd swap my C-3 (actually, it's a C-4 now)
for a TH-7. If the KT-34XA is, in fact, 2-3 dB better in forward gain than
the C-3, it'd be a harder choice. But I like the design margins the C-3/4
gives me in all the other areas that are important to me - weight, wind
area, and simplicity/reliability.
73, Pete Smith N4ZR
n4zr@contesting.com
West (bigawd) Virginia
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