Did you ever stop to think that the usual tri band trapped beam uses a single
coax feed for all bands and to get a 50 ohm feed point impedance it is
necessary to detune the elements from their best length for gain or f/b. In
addition, the element spacing is the same for all bands so another compromise
there.
73, Dan, N5AR
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf Of Jerry K
Sent: Wednesday, October 29, 2008 7:05 AM
To: Tower Talk
Subject: Re: [TowerTalk] Lossy traps?
A fixed element non-trapped tribander with only three elements appears
to be an oxymoron. In the only comparison I can offer, I ran a standard
Moseley TA-33 trapped tribander for years with decent results, finally
went to a Force 12 C3XLD (3 bands, no traps, but F12 doesn't call it a
"tribander") and the difference was literally astonishing. But the F12
was a $1400 antenna with 10 full-length elements on a 33' boom with
separate feeds for each, weighs 75 lb, and is essentially three
monobanders on a common boom (10M used 4 elements). From day one the
Force 12 was the proverbial 'nuclear weapon' in a pileup. The difference
was dramatic, and yes, people 5000 miles away and more certainly did
notice the difference. Just for fun, I also occasionally ran QRP to that
antenna and had a blast trying to convince Europeans I really was
running only 800mw. :)
73, Jerry W5KP
foxbw@comcast.net wrote:
> How "lossy" are traps on a trap tri-bander? Some manufacturers of
> non-trapped tri-banders cite the lossy aspect of traps, but how real is that
> loss? Can it be measured? Would someone 500 or 5000 miles away notice the
> difference between a trapped tri-bander and a similar tri-bander antenna
> without traps? Notice I said tri-bander, not mono-bander, SteppIRs, etc.
>
> Anyone have any idea?
>
> TNX / 73,
>
> Barry - W1HFN
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