[TowerTalk] Telrex TB5EM hairpin

[kk9a at arrl.net]

There's probably no degradation due to not using the hairpin.  It only helps
match the impedance of the antenna to your 50 ohm coax.    I'm curious how a
single hairpin works on a multiband antenna.  I would think you'd need a
much larger hairpin on 20m than on 10m.   Not using a balun, however will
probably result in feeline radiation and a very distorted pattern.

John KK9A


----- Original Message -----
From: "RICHARD BOYD" <ke3q at msn.com>
To: <n8de at thepoint.net>; <N4CW at aol.com>
Cc: <towertalk at contesting.com>
Sent: Thursday, September 30, 2004 15:22
Subject: [TowerTalk] Telrex TB5EM hairpin


Let me ask you TB5EM guys a question.

I have had one for years and use it every year for Field Day on our RTTY
station.  We pressed it into service when someone said, "Anyone have a
tribander we can use?" and I had it here in storage.  Quickie-style, we just
attached center conductor and braid, each, to each side of the split driven
element with stainless steel hose clamps, didn't use the stainless steel
screws that go through the tubular Cycolac (or whatever it is) insulator at
the center.  It worked great, 1:1 SWR, the appropriate SWR curve, good gain
and directionality.  We have never seen any reason to change it.  I've put
it up on a portable tower at home and have been using it and it's been very
effective here too.  I came across a second TB5EM and plan to feed it the
same way and have them up in a stack.

So, getting to the question:  What degradation in performance should I be
expecting to see by virtue of not having the balun or hairpin?

73 - Rich, KE3Q