On Thu,3/3/2016 9:56 AM, Kelly Taylor wrote:
Hi Jim,
Further to your tutorial, particularly the reference to inductance at a current peak, I note with
interest a reference I remember from the manual for my old HF6V (the OP’s antenna is the
HF2V, IIRC): in it, Butternut claimed the lumped inductance at the base of the antenna was not
“base loading”.
But if a lumped inductance at the base of an antenna isn’t base loading, what
is it?
I don't know anything about the design of this antenna, so won't comment
on it specifically. However -- the feedpoint Z of a short vertical is
quite low, so one good matching technique might be a transformer
(including an auto-transformer) that steps that low Z up to 50 ohms. On
160M, that auto-transformer might take the form of a tapped coil, with
the coax connected between ends of the coil antenna connected between
the tap and bottom of the coil.
My HF6V worked as expected for a vertical on 40 and up. On 80, I’d have had as
much luck setting a dummy load in its place. I always got the impression the problem
on 80 was the inductance was compressing the current peak to between the feedpoint and
the coil and any radiation was primarily into the fence, shed and trees, rather than
into the ether.
Again, I don't know enough to comment on the Butternut. But what do you
have for a radial/counterpoise?
73, Jim K9YC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|