[TowerTalk] Re: Telrex TB5EM hairpin

[Don Havlicek]

"It worked great, 1:1 SWR...."
Where was this fantastic SWR measured? .. at the antenna? .. or at the 
far end of the feedline?  I'll bet that it's the latter case.
The balun and hairpin are designed to obtain the best SWR on this 
tri-band antenna while eliminating [to the best extent] the currents on 
the coax shield ...
For Field Day .. anything that 'seems' to work ...WORKS! [been there ... 
done that!
Put the balun and hairpin back on and I'm sure you'll find the antenna 
actually does what it is DESIGNED TO DO.
Don
N8DE

RICHARD BOYD wrote:
> 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
> 
> 
> ----- Original Message ----- 
> From: "Don Havlicek" <n8de at thepoint.net>
> To: <N4CW at aol.com>
> Cc: <towertalk at contesting.com>
> Sent: Thursday, September 30, 2004 10:32 AM
> Subject: Re: [TowerTalk] hairpin
> 
> 
> 
>>Just measured mine.
>>
>>The 'loop' is 25.5 inches either side of the boom attachment point, thus
>>is 51 inches overall.
>>
>>The shape is almost a continuous curve from driven element attachment
>>point to boom attachment point EXCEPT the first 3 inches [nearest the
>>driven element] at quite 'straight' with a bend at the 3 inch point.
>>
>>Don
>>N8DE
>>
>>N4CW at aol.com wrote:
>>
>>>No dimensions are given in the "Assembly Instructions" sheet that I 
>>>have.
>>>Direct measurements will have to be made.
>>>Telrex wasn't long on details...,"If you have followed simplified 
>>>assembly
>>>sheet carefully, you are ready to connect your 52 Ohm co-axial to the 
>>>'Balun'
>>>provided. Mount the antenna in the clear, 34 fet or higher." Also, "Do 
>>>not
>>>force, alter, modify, or try any inventions! Telrex has precision-tuned 
>>>and matched
>>>this antenna to provide optimum 10, 15, and 20 meter gain, F/B ratio, 
>>>and
>>>'balanced-pattern'."
>>>No dimensions, other than hardware sizes, are given.
>>>73,
>>>Bert, N4CW/1
>>>_______________________________________________
>>>
>>>See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless 
>>>Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
>>>any questions and ask for Sherman, W2FLA.
>>>
>>>_______________________________________________
>>>TowerTalk mailing list
>>>TowerTalk at contesting.com
>>>http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>>
>>
>>_______________________________________________
>>
>>See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless 
>>Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
>>any questions and ask for Sherman, W2FLA.
>>
>>_______________________________________________
>>TowerTalk mailing list
>>TowerTalk at contesting.com
>>http://lists.contesting.com/mailman/listinfo/towertalk
>>
> 
>