[TowerTalk] KT-34A on 30ft guyed telescoping mast?

[Chris Adams]

Hi David,

I won't pretend to know the answer...  however there was an excellent
article in the May 1994 QST by Bob Haviland titled "Amateur Use of
Telescoping Masts".  The article examines using a 50' telescoping mast
and talks about limitations, etc.  Judging from the article, the KT-34A
would NOT be appropriate for a 50' mast.  However, as you understand the
failure modes it certainly wouldn't surprise me if the KT-34A could be
used on a 30' properly installed mast.

One thing is for sure, we need to know more about the mast before it
would be possible to determine if it would work if properly installed
(is it 16 or 18ga steel, etc).

73's

chris adams, n4vi

David Rich wrote:
> 
> Hello,
> 
> I presently have a 30 foot telescoping mast located up against the west
> side(long side) of my house.  The long side of the house is
> approximately 50 foot running North and South.  The mast is presently
> secured with eight guys and one small house bracket.  Four of the guys
> are at the top and four are somewhat higher than the midway point up the
> mast.  The house bracket is approximately twelve to fifteen feet from
> the bottom.  Two of the upper guys, along with the coresponding midway
> guys, are mounted to the roof using two screw-in mounting hooks
> seperated by several feet.  Each pair of upper and midway guys shares
> the same mounting hook.  The other two pairs of guys travel several feet
> and connect to two fence posts approximately 100 feet apart.
> 
> I presently have a Ham II rotator along with a R7 vertical(2ft squared),
> a Cushcraft A27010S 2 m/ 70cm 5 element yagi(.75ft squared), and a 25
> element 70cm ATV yagi(2ft squared).  The two beams are connected to a
> 8ft light steel section of mast that is mounted horizontally above the
> rotator.  This arrangement has been up for several years and has not
> given any indication of being unsafe under severe weather condition.
> 
> The R7 vertical indicated a intermittent VSWR problem on 40 meters
> during the recent CQWW CW contest.  I need to remove it from the mast to
> inspect it and try to repair what ever is the problem.  This is the
> second time I have had some sort of problem with this vertical I
> purchased new about 3 or 4 years ago.  I am considering the purchase of
> a KLM KT-34A tri-band beam and putting it up on the mast instead of the
> R7.  This is KLM's smaller tri-bander.  It weighs 45 pounds and has a
> 6ft squared windload.  The beam is 27 pounds heavier and has 4ft squared
> more windload than the R7.  Will the addition of the KLM tri-bander
> along with the above mentioned smaller beams be too much and unsafe to
> use on the existing 30 foot telescoping mast?  I live in Jackson County,
> Missouri were the wind speed can exceed a minimum of 70 MPH.
> 
> Thanks,
> 
> Dave Rich KG0US
> kg0us@swbell.net
> 
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