Topband: Low band antenna project questions

[Richard (Rick) Karlquist]

On 3/7/2016 11:05 AM, John Pescatore via Topband wrote:
> It is resonant on 160, with about 16 radials out now,
  so don't need a tuner there. I've tried it on other bands
  with a tuner in the shack, and performance is horrible.
> Could have been so much loss in the coax that a base
of the antenna tuner might change things but I wouldn't
  want that to be my only HF antenna.
>
> 73 John K3TN

If it is series resonant on 160, it is likely to be
approximately parallel resonant on 80 and 40, with
a very high drive impedance.  This severe mismatch
will give you a lot of loss in the coax, even though
it might be low loss when matched.  A tuner at
the base of the antenna will solve this problem and
you should have excellent results.  The tuner,
however, will have to be one that can match an
impedance in many 100's or maybe 1000's of ohms.
Not just any tuner.

Rick N6RK