[TowerTalk] Aluminum tubing slip joints seized - my final answer

[Mike Ryan]

The poly rope was placed in the portion of the elements beyond the traps,
where the aluminum elements were more prone to failure due to the constant
vibration.  I don't think the rope was used on the INSIDE half of the
elements between the traps and the boom.  The 10m elements on the TH6/7 for
example had a rather long section of it as I recall. It was advised to GLUE
the ends so that it would not creep or gather in one end and over time and
negate the dampening effect. Now, that's from memory of an antenna that I
put in over 20 years ago, so don't quote me. -Mike

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Robert Chudek - K0RC
Sent: Thursday, September 08, 2011 12:46 AM
To: Mike & Becca Krzystyniak
Cc: TowerTalk at contesting.com
Subject: Re: [TowerTalk] Aluminum tubing slip joints seized - my final
answer

Hi Mike...

No, unfortunately I don't know much about the Telrex designs. When they 
were manufacturing antennas I was lucky to be able to afford 150 feet of 
copper wire, some TV ribbon cable, and an 807 CW transmitter! (Knight 
Kit T-50)

But I do know that HyGain put rope in some of their antennas for the 
dampening effect. I think my TH-5DX had ropes in some of the elements 
(or maybe it was the Cushcraft ?).

73 de Bob - K0RC in MN
------------------------------------------------------------------------

On 9/7/2011 9:30 PM, Mike & Becca Krzystyniak wrote:
> Hi Bob,
>
>     As you may know, the original Telrex designs used a double wall tip to
> dampen the low rate oscillations caused by the wind or other (and many
used
> the corona tear drop too).  The double walls on the element tips of my
> 20M436 were in the neighborhood of 4' - 6'.  Put in backwards the element
> tips broke off in just a few months.  Double wall toward the boom and none
> failed, ever.  And it never rattled in the wind either.  Element wig-wag
> became my next foe...
>
> 73's  Mike K9MK
>
>
>
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Robert Chudek -
K0RC
> Sent: Wednesday, September 07, 2011 6:16 PM
> To: TowerTalk at contesting.com
> Subject: Re: [TowerTalk] Aluminum tubing slip joints seized - my final
> answer
>
> The issue was a little more "complex" than I first thought.
>
> I discovered there wasn't a simple 4" to 6" of overlap, but about 48"
> instead. It's apparent this antenna was not assembled to manufactures
> specifications. The extra tubing did not add to the mechanical strength.
> It only added unnecessary weight. The excess tubing was at the tip end
> of the tube, not the tower end.
>
> What did work to some extent was inserting another (long) tube from the
> opposite direction and driving the inside tube toward the tip. This was
> only partially successful and I had to resort to the hacksaw. Actually,
> I used a tubing cutter for a clean cut. Then I drove the remaining
> inside piece back toward the tower end. I had to use this method on both
> halves.
>
> Pulling a few pieces from my aluminum pile I was able to reassemble the
> antenna. At the same time I added stiffening to the junctions by adding
> internal sleeves where needed.
>
> The remaining task is to model this (again) and see how to make a 62.5
> foot element resonate at 7.1 MHz. I'm thinking capacity hats somewhere
> out near the ends, like the Cushcraft 2 element 40m yagi.
>
> 73 de Bob - K0RC in MN
> ------------------------------------------------------------------------
>
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