John Ferrell wrote:
I am considering purchasing a remote auto tuner for my continuing
tinkering with verticals. My current focus is on 80-160 meters with
33+ foot verticals. The auto tuners specs claim a max inductance of
around 32 uh. The tuners computed with the ARRL program TLW20 require
much larger values of inductance.

Will the Auto tuner (SGC-237) that claims to match any wire greater
than 28 feet long really do it?

John Ferrell W8CCW

As others have noted, the auto tuners will have no trouble matching a 33
foot vertical on either 80 or 160 meters, even over sea water.

Using one at the antenna may reduce losses in your coax since the swr
will always be low.

The auto tuners will introduce their own losses, as will any antenna
tuners, although with shorter antennas the losses may be greater. QST
had an article in which auto tuner losses and matching ranges were
measured and I think compared with conventional tuners. If I recall, the
results were less unfavorable toward auto tuners than I had expected.

To reduce auto tuner matching losses to insignificant levels, you might
consider adding some lumped inductance at the base of your vertical (or
even better, part way up as in center-loading). You can add a
capacitance hat as well. If you cause the 33 foot antenna to appear
resonant at either 80 or 160, you will see reduced auto tuner matching
losses on both bands. Just a rough approximation to the required number
of turns ought to work. You're only trying to provide enough external
loading to reduce the tuner's losses. Resonance really doesn't matter
much. If you do this, you should be able to enjoy the ease of QSY
without a serious loss penalty and without a need to switch taps or
retune manually.

Of course your 33 foot vertical resonant at 80 or 160 meters may not
perform well at 40 meters and above, or worse, may not provide an
impedance your tuner can handle at those frequencies.

Chuck, NT3G


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