On 4/19/2020 8:51 AM, ab2tc wrote:
I totally agree with your last statement about the tuner placement.
The importance of a tuner being at the feedpoint depends entirely on the
antenna, the frequency(ies), and the feedline. The lower the operating
frequency, and lower the feedline loss characteristics, and the lower
the mismatch, a tuner in the shack can work quite well at moderate power
levels. AD5X, who does product reviews for ARRL, reviewed the "43 ft
vertical," which is notoriously difficult to match. One solution he
found was a 4:1 unun at the feedpoint and 1/2-in hardline to the shack.
For high power on 160 and 80M, he used a tuner at the feedpoint.
Some years ago, I successfully loaded a vertical on 80M that was
resonant on 160M, hence a VERY high impedance at the feedpoint. The
feedline was RG8 and only about 40 ft long, so I was able to load it
quite successfully with a Ten Tec 238 tuner in the shack and a legal
limit Ten Tec tube amp.
On 60M, I'm currently loading a high 80M dipole fed with 160 ft of RG11
using the tuner in the KPA1500. The amp, of course, is throttled back to
less than 100W. I'm not the loudest signal on the band, but I've worked
into EU and SA in a few evenings on the band.
73, Jim K9YC
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