[TowerTalk] finding resonant frequency of a shunt-fed tower for 160

[wa9als@starband.net (WA9ALS - John)]

I'm interested in this too, so will jump in now.  My main question now is:

I have a C31XR at 72 ft - The elements are -not- grounded.  Thus I assume
much less (or none?) capacitance hat effect.  I therefore assume I can still
work out a shunt feed for -some- frequency(s), but they will likely be
higher freq than if I had grounded elements and therefore more capacitance
at the top?

What do you think would be reasonable to shoot for with a 70 ft tower with
the ungrounded elements of the C31?  40M?  Maybe 80M?  Doubt 160M??  Pete,
I'd be interested in whatever appraoch you end up taking with your project
too!  Thanks

----- Original Message -----
From: Bob Alexander <realex@flash.net>
To: Pete Smith <n4zr@contesting.com>; <towertalk@contesting.com>
Sent: Monday, July 30, 2001 11:55 AM
Subject: RE: [TowerTalk] finding resonant frequency of a shunt-fed tower for
160


>
>
> Pete,
> Find a copy of May, 1975 Ham Radio magazine and check out the article
titled
> "How to Design Shunt-feed Systems for Grounded Vertical Radiators" by John
> True,
> W4OQ.  I do not think there has ever been a better "how to" article
written
> about
> tower matching.
> 73, Good Luck
> Bob, W5AH
>
> -----Original Message-----
>
> This is my ignorant question for today -- with only an antenna analyzer,
> how can I determine the resonant frequency of my tower?  I plan to attach
a
> first-attempt at shunt feed at about the 30-foot level, with 30-inch
> spacing from the tower.  Can I tell from the analyzer reading at the
bottom
> of that shunt wire where the tower is resonant?  Do I need to put the
> series capacitance in before attempting the measurement?  Or is it all
> fruitless?
>
> Clearly my education was neglected or I'd know the answer, so thanks for
> your help and patience.
>
> 73, Pete N4ZR
>
>
>
>
> -----
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