[TowerTalk] C3 value?

n8de at thepoint.net n8de at thepoint.net
Tue Jul 15 08:12:29 EDT 2008


Slight correction, Gene.

The LPDA is at LEAST a two-element radiator.  On some frequencies [at  
or near the mid-point of its design] it will approximate a  
three-element beam.

This is because at least one of the longer elements will act like a  
reflector, while one of the shorter elements will act like a director.

Dr. Duhamel's work at Collins did NOT go unnoticed by this geezer.
73
Don
N8DE

Quoting Gene Smar <ersmar at verizon.net>:

> Jim:
>
>      FWIW - A LPDA is at best a two element radiator.  The gain will  
>  likely be less than that of a three element Yagi.  The LPDA  
> provides  a wider bandwidth than the Yagi, hence its popularity with  
> military,  embassy, etc. installations.
>
>
> 73 de
> Gene Smar  AD3F
>
>
> From: jim Jarvis <jimjarvis at optonline.net>
> Date: 2008/07/14 Mon PM 01:41:10 EDT
> To: towertalk at contesting.com
> Subject: [TowerTalk] C3 value?
>
> TT:
>
> I just picked up a 12 year old Force 12 C3, in an estate/takedown
> situation.
> At the same time, I had two guys approach me, to buy it from me.
>
> At the moment, I'm undecided whether to put this up, or to put up my
> T8 lpda,
> for general purpose use, and light-duty contesting.
>
> Other than rusted uBolts which hold the elements on, the antenna is
> clean and
> in good shape.    This is the 3 element version, which I take to be
> the original C3.
> It uses F12's single feedline, direct connected for 20m, and
> capacitively coupled for 10 and 15m.
> I guestimated a 16' boom length.   We were all too tired to measure
> it, after the
> takedown.
>
> So, I have a couple of questions:
>
> 1)  What's a fair market value for the antenna?
>
> 2)  Does anyone have first hand experience with it, on 12 and 17m?
> F12 says it works there.
>
> 3)  Does anyone have first hand experience of performance vs. an lpda?
>
> I have some thoughts on item 3.   That is, the Tennadyne logs
> outperform trapped 3 el. tribanders,
> due to their efficiency.   The F12 antenna, however, is three
> monobanders on a common boom.
> No traps.   So, I would expect the C3 to slighty outperform the log,
> on three bands, stipulating that f/b, gain,
> and vswr curves may not align to actually produce the hoped for best-
> cast performance.
>
> Your thoughts?
>
> n2ea
>
>
>
>
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