[TowerTalk] C31-XR versus KT36XA

Fri Oct 3 12:59:23 EDT 2003

Brain - under the heading of - for what it is worth...

That is me on that tower - the lower guy on the tower, and I used that 
antenna for about a decade at the station at my parents home in 
Homestead, FL until Hurricane Andrew took it down.

In my opinion the antenna performed very well and despite those who told 
me it was a dog on 15 meters I came in second twice in the CQ WW CW as a 
21 MHz monoband entrant - losing once to a ham in Virginia who 
out-Europeaned me (in Florida) and the other time to a W5 who out JA'd 
me...

All that time I never felt the antenna was a disappointment - on the 
contrary it changed my opinion on tribanders to some extent. It was not 
the traditional "suckermaster" which presented a near 50 ohm low SWR 
antenna to the rig on three bands and not much more. It did have pattern 
AND DID BUST PILEUPS.

The biggest downside of the KLM tribanders is a function of their 
complexity.  There were so many little pieces that it was that 
antithesis of the KISS (keep it simple stupid) rule and as I now gather 
from your posting is was so much  so we had it put together wrong!

Even built wrong I could not think of another tribander on the market AT 
THAT TIME I would have rather been using.  Today, the multiple 
monobanders on a common boom triband antennas like the Force 12 antennas 
are to me more likely to have less problems and fewer assembly errors 
than the KT's.

73,

Jim, K4OJ

203 11 59

Bryan Rambo wrote:
> Sorry for the delay Jim, I've been on vacation.
> 
> The KT-34XA is constructed so that the coaxial capacitor sections are
> oriented to the front on some elements and to the rear on the other
> elements.  Going from the reflector to the last director, they should be
> oriented rear-front-rear-front-rear.  The XA pictured in the Antenna Book
> article has all the capacitor sections to the front.
> 
> I pointed that out just to show how easy it is to make a mistake when
> building an XA.  I just wondered if the same mistake might have been made on
> the XA used in Steve's and Ward's tribander report.  I wonder if they have
> photos?  I also wondered if they ever confirmed whether or not the XA used
> in the report was one of those that had the defective tubing.
> 
> 73 - Bryan W4WMT
> 
> -----Original Message-----
> From: Jim White, K4OJ [mailto:k4oj at tampabay.rr.com]
> Sent: Friday, September 19, 2003 9:37 AM
> To: bryanr at bometals.com
> Subject: Re: [TowerTalk] C31-XR versus KT36XA
> 
> 
> I am looking st the picture  -  how are those backwards?
> 
> Thanks,
> 
> Jim
> 
> Bryan Rambo wrote:
> 
>>Ward, thanks for your careful explanation below.  And again, I didn't mean
>>to imply that you had botched data in the tribander report.  Sorry for not
>>being more precise with my words :-(
>>
>>I wonder if it was ever confirmed that the KT34-XA used in the report was
>>indeed one of the units with defective tubing?  The reason I ask is that
> 
> it
> 
>>is very easy to put one of those antennas together wrong.  As evidence of
>>that, look in the ARRL Antenna Book (editions 17,18,19) in chapter 22 and
>>take a gander at the KT34-XA depicted there.  Three of the elements are
>>mounted backward on the boom!!!
>>
>>73 - Bryan W4WMT
>>
>>-----Original Message-----
>>From: towertalk-bounces at contesting.com
>>[mailto:towertalk-bounces at contesting.com]On Behalf Of Ward Silver
>>Sent: Tuesday, September 16, 2003 11:50 PM
>>To: Towertalk Reflector
>>Subject: Re: [TowerTalk] C31-XR versus KT36XA
>>
>>
>>A slight clarification on the exact problem with the KT34XA...
>>
>>When we started presenting data, as Steve said, several other XA owners
> 
> came
> 
>>up and said, "Mine acts JUST LIKE THAT and nobody has ever been able to
>>explain why or fix it!" Other guys (the majority) couldn't repeat the
>>behavior and had never observed it.  At Dayton in 2000, I was having
> 
> dinner
> 
>>with some DL hams (can't remember exactly who, apologies DL hams) and they
>>said, "You know, DL2? figured it out."
>>
>>To make a long and mysterious story short, KLM received and used an
>>out-of-spec shipment of tubing for the 15-meter capacitor sections.  The
>>capacitance is formed by the OD of the inner tube and the ID of the outer
>>tube.  The outer tube had the right OD, but the wrong wall thickness (too
>>thick) and so the ID was too small and the resulting capacitance too large
>>and the resulting frequency of minimum SWR too low. (Follow me through
> 
> that
> 
>>sentence?)
>>
>>The specified wall thickness for the outer tube was not the common value
> 
> for
> 
>>tubing of that OD. Somebody either ordered or shipped the common
> 
> (too-thick)
> 
>>tubing and KLM's QC didn't catch it.  The difference wasn't enough to
>>prevent the plastic end caps from going in - it was just a few thousandths
>>of an inch too thick - so the problem went unsolved for years.
>>
>>If you have an XA that tunes up too low on 15-meters, contact M2 because
>>they have a retrofit kit that will fix it up.  The suspect antennas seemed
>>to also have blue end caps on the tuning capacitor tubing, but it's not a
>>one-to-one relationship.
>>
>>Most of the credit goes to the DL guys for having the smarts to make the
>>right measurements and deduce what had happened.  We published the data
> 
> and
> 
>>caused the connection between cause and effect to become known.  And THAT,
>>my friends, is why publishing your test data is so important.  That is
>>SCIENCE, even if it is applied science.  As Isaac Asimov said
>>(approximately), "Breakthroughs in science never start with 'Eureka!'
> 
> They
> 
>>start with 'Hmmm, that's funny...'"
>>
>>73, Ward N0AX
>>
>>----- Original Message -----
>>From: <K7LXC at aol.com>
>>To: <bryanr at bometals.com>; <towertalk at contesting.com>
>>Cc: <hwardsil at centurytel.net>
>>Sent: Tuesday, September 16, 2003 8:26 PM
>>Subject: Re: [TowerTalk] C31-XR versus KT36XA
>>
>>
>>
>>
>>>In a message dated 9/14/03 9:36:16 AM Pacific Daylight Time,
>>>bryanr at bometals.com writes:
>>>
>>>
>>>
>>>>I'm glad you brought up the business about Steve & Ward's (otherwise
>>>>excellent) tribander report.  It's a real shame that the ONE antenna
>>>
>>that
>>
>>
>>>>got botched was the XA.
>>>
>>>   Actually several other XA owners told us that theirs were identical to
>>>the test antenna.
>>>
>>>   FYI any XA that came out of KLM once they moved to Washington State
>>
>>was
>>
>>
>>>suspect since they made wholesale aluminum substitutions that created
>>
>>problems.
>>
>>
>>>They couldn't get the parts from their suppliers because they didn't pay
>>
>>them
>>
>>
>>>so they shipped anything they had in stock that was close.
>>>
>>>
>>>
>>>>It sure would have been interesting to see
>>>>how the XA stacks up to the more recent designs
>>>
>>>   Sure. Get us a KT36XA and we'll be happy to include it in our next
>>
>>round
>>
>>
>>>of tests.
>>>
>>>Cheers,
>>>Steve    K7LXC
>>>TOWER TECH
>>>Champion Radio Products
>>>
>>>
>>
>>
>>
>>_______________________________________________
>>
>>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
>>
> 
> 
> 
> 
> _______________________________________________
> 
> 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.
> 
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