[TowerTalk] KT43XA/KT36XA Rebuild

Tue Mar 8 19:38:48 EST 2005

This out of diameter issue is discussed in the M2 literature that comes 
with the rebuild kit.  You did check the wall thickness, didn't you?  
What does M2 say about your problem?  Call them.  Phil  KB9CRY

Joe - KC2TN wrote:

>I recently rebuilt mine to a KT36XA also but did not experience the SWR
>problems on 15. I can send a graph of a before and after comparison if you
>like.
>
>The only thing I recall about 15 meters is with the 15M capacitor tubes
>being of the wrong size in some shipments due to an out of spec tube supply.
>
>I found this in the archives:
>
>To:  "Towertalk Reflector" <towertalk at contesting.com>
>Subject:  Re: [TowerTalk] C31-XR versus KT36XA
>From:  "Ward Silver" <hwardsil at centurytel.net>
>Reply-to:  Ward Silver <hwardsil at centurytel.net>
>Date:  Tue, 16 Sep 2003 20:49:48 -0700
>List-post:  <mailto:towertalk at contesting.com>
>
>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
>
>
>73 and gud luk with your rebuild, mine works great!
>
>Joe - KC2TN
>"If you're sure of everything,
>        and it still doesn't work,
>           one of the things you're sure of is wrong!"
>
>
>-----Original Message-----
>From: towertalk-bounces at contesting.com
>[mailto:towertalk-bounces at contesting.com]On Behalf Of smith.l at mchsi.com
>Sent: Monday, March 07, 2005 8:41 PM
>To: towertalk at contesting.com
>Subject: [TowerTalk] KT43XA/KT36XA Rebuild
>
>
>I recently completed rebuilding and upgrading my old KT34XA to a KT36XA and
>have
>encountered a problem that I need help with. This is the 5th time I have
>updated
>this antenna since I got it in 1980 and mechanically it is much better than
>previous versions.
>
>My problem is with the SWR on 15 meters. It is 1.8:1 across the band while
>20M
>and 10M are virtually flat from end to end. SWR was checked on sawhorses and
>I
>figured it would improve on top of the tower. I was wrong-it remained 1.8:1.
>We
>lowered it back down and remeasured everything, rechecked all elements,
>etc.,
>and found nothing out of whack. It is assembled correctly and all elements
>are
>oriented properly.
>
>Does anyone have any experience with this? I am sure it has to be something
>simple that I am overlooking but if any of you could point me in the right
>direction it will be appreciated.
>
>Thanks.
>Larry Smith, N4FD
>_______________________________________________
>
>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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>
>_______________________________________________
>
>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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