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Re: [TowerTalk] XM-240 Shorty-Forty: X-Hat Modification- Update

To: "'Tower and HF antenna construction topics.'" <towertalk@contesting.com>
Subject: Re: [TowerTalk] XM-240 Shorty-Forty: X-Hat Modification- Update
From: "Chet" <chetmoore@cox.net>
Reply-to: "Tower and HF antenna construction topics." <towertalk@contesting.com>
Date: Wed, 10 Feb 2010 01:56:51 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Hi Dick,

I think you mentioned large birds on on yours xm-240.  I have seen a couple
of doves on mine but I guess I have been lucky.  With doves sitting on it,
it really does make the elements droop. Mine has been up 7 years  now and no
problem.  I bought this used from K3OO who had it up for several years
before that.   This one took a lightning hit which Took out one of the coils
and is one Of the reasons he sold it.  I got a new coil from cushcraft about
10 days after I got the antenna home, I put it back up At 75 feet and its
never blinked even through 5 hurricanes. I am about 7 miles off the water.
Great antenna, I would definitely buy another one. Only once have
I seen any ice at this qth. In truth this XM-240 has exceeded my wildest
expectations. 

73

Chet N4FX 

-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of RLVZ@aol.com
Sent: Tuesday, February 09, 2010 4:55 PM
To: towertalk@contesting.com
Subject: [TowerTalk] XM-240 Shorty-Forty: X-Hat Modification- Update

 
Hi Guys,
 
Thank You for the input regarding my XM-240 Shorty-Forty X-Hat rods  
breaking and falling off.
 
For those who asked, the X-Hat Rods are 34-1/2" in length.
 
I just went out and inspected the X-Hat assembly on my 1 year old  XM-240.  
It is constructed as Joe said the original X-Hats were  constructed: "The 
original X-hat elements were solid rod 3/16" in  diameter  with a 1.25" long

by 3/8" OD sleeve crimped over the  center of he rod before drilling for the

#8-32 x 1.75" mounting  bolt."
 
Therefore, the "1.25" long by 3/8" sleeve crimped over the center of the  
rod" is a part of my X-Hat.  I am very happy that most people have not had
a 
problem with their X-Hat rods breaking and falling off!  But if you think  
about it, the strength of the small 3/16" rod is almost entirely  
compromised when it was drilled thru to accomadate the #8-32  mounting bolt
which is 
1/8" in diameter.  Therefore, about the only  thing holding the rod together

is the 1.25" long by 3/8" OD sleeve  crimped over the center... which only 
provides 1/2" of support on each  side of the hole!  (and how strong is a 
crimped sleeve)
 
I think we discovered why the "on the tower" life of my new XM-240 has not  
exceeded 1 month either time it was up.  Either vibration from the  wind 
and/or birds landing on the weakened 3/16" rods... cause them to  break
apart. 
 By the way, when the 2 different 3/16" rods fell to the  ground the 3/8" x 
1.25" sleeve was no longer attached to any part of the 4  remaining rods 
pieces.  I believe this indicates that the crimped sleeves  probably failed.
 
As an option to replacing the X-Hat with extended elements, perhaps I  
might consider using 3/8" aluminum rod with a 2nd sleeve over the  center
where 
drilled.
 
73,
Dick- K9OM
 
     
 
 
 
 
 
 
 
In a message dated 2/9/2010 4:12:52 PM Eastern Standard Time,  
na8w@hotmail.com writes:

That's  exactly what happened to mine.

Darl   NA8W

--------------------------------------------------
From: "Joe  Subich, W4TV" <lists@subich.com>
Sent: Tuesday, February 09, 2010  3:22 PM
To: "'Tower and HF antenna construction topics.'"  
<towertalk@contesting.com>
Subject: Re: [TowerTalk] XM-240  Shorty-Forty: X-Hat Modification

>
>> I wonder why they  fall off?
>
> The original X-hat elements were solid rod 3/16" in  diameter
> with a 1.25" long by 3/8" OD sleeve crimped over the  center
> of he rod before drilling for the #8-32 x 1.75" mounting  bolt.
>
> Newer antennas - or at least some production runs -  appear to
> lack the crimped sleeve as they fracture through the  mounting
> hole due to vibration.  My guess is that the sleeve  was
> eliminated as a cost cutting measure <G>.
>
>  73,
>
>   ... Joe,  W4TV
>
>
>
>
>
>
>> -----Original  Message-----
>> From: towertalk-bounces@contesting.com
>>  [mailto:towertalk-bounces@contesting.com] On Behalf Of Gregg Seidl
>>  Sent: Tuesday, February 09, 2010 1:57 PM
>> To: Tower and HF antenna  construction topics.
>> Subject: Re: [TowerTalk] XM-240 Shorty-Forty:  X-Hat Modification
>>
>>
>> I wonder why they fall  off?  I've never heard of that. Mine
>> have been up  for
>> 6 years now.  Gregg  K9KL
>> ----- Original  Message ----- 
>> From: <RLVZ@aol.com>
>> To:  <towertalk@contesting.com>
>> Sent: Monday, February 08, 2010  4:43 PM
>> Subject: [TowerTalk] XM-240 Shorty-Forty: X-Hat  Modification
>>
>>
>> > Hi Guys,
>>  >
>> > I've had problems with the X-Hat Rods falling off of my  XM-240.
>> > Therefore, I would like to eliminate the X-Hat by  lengthening the
>> > elements.  I'm wondering if anyone has  done this
>> successfully and how
>> > much length must  be
>> > added to the elements?
>> >
>> >  Or if anyone has modeled the removal the XM-240 X-Hat by
>>  lengthening
>> > the elements... please share what element lengths  you came up with.
>> >
>> > Thanks!
>>  >
>> > Dick- K9OM
>> >  _______________________________________________
>> >
>>  >
>> >
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>> >  http://lists.contesting.com/mailman/listinfo/towertalk
>>  >
>> >
>>
>>
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