[TowerTalk] log periodic choice

jim Jarvis jimjarvis at optonline.net
Fri Sep 12 12:34:30 EDT 2008

Having owned a Tennadyne T8, and a 3 el SteppIR, I think I can wade  
in on this

First, although the T8 is essentially a 2 element beam on any band,  
as others have
observed, it doesn't suffer from trap losses typical of trapped  
tribanders.   It out performed
my KT34a, although not by a lot.    You should expect around 6dBd  
gain, and 20dB f/b, with
no diddling around to get it tuned.

I replaced the T8 with a 3 el SteppIR, after a tree ate the T8.     
The steppIR was another step
up in performance.   At that time, it was $1k, as compared with about  
$650 for the T8.   Now,
the SteppIR runs about 2x the price of the T8.

If you're really turning radius constrained, the SteppIR is 19.7',  
and adding 30/40 takes that to 20.0'.
The T8 is spec'd at 20.9'.   However, in my VT installation, I was  
forced to fold down the outer 2' of
the longest element,  to clear a tree.    Seemed to work fine.   More  
like 18'.

(fill tube with sand.  Plug ends.   Heat liberally with propane torch  
for 12-18".  Fold tube over large
juice can to establish the radius.)

Assuming that I wasn't dollar constrained, and didn't have a turning  
radius problem with 20', I would
choose the 3 el steppIR with 30/40.    If either money or radius were  
a problem, I'd go with the T8.

The ONLY downside to the T8, as compared with the tuned antenna, is  
that when the MUF is high,
the LPDA allows SW broadcast above 21,450 to ride into your rx front  
end.    When the band's open,
these guys are 60 over 9 or more, and can produce some interesting  
intermod.   The tuned
antenna doesn't permit these large signals to get into the rx.

'course, that won't be a problem for another couple of years, yet!


Jim Jarvis, MBA
President - Executive Coach
The Morse Group, LLC

People-Process-Strategy:  Achieving Results in a Changing World
coach at themorsegroup.biz
Read our latest newsletter.  Go to:  http://www.themorsegroup.net/ 

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