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

Wed Feb 10 01:00:04 PST 2010


Chet wrote:
> 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.
Man, but am I Jealous!  Nothing like coming out 3 or 4 times a year to 
see the elements on your antennas loaded with ice and pointing at the 
ground.  That is a lot of  flexing but bad as they look they've always 
gone back up in place. OTOH my generator shed is directly under the 
beams. The shed is one of those vinyl prefab units. I don't think it 
even slows down a foot long piece of ice.  Parts are easily replaceable 
though.

73

Roger (K8RI)
>  In truth this XM-240 has exceeded my wildest
> expectations. 
>
> 73
>
> Chet N4FX 
>
> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of RLVZ at aol.com
> Sent: Tuesday, February 09, 2010 4:55 PM
> To: towertalk at 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 at hotmail.com writes:
>
> That's  exactly what happened to mine.
>
> Darl   NA8W
>
> --------------------------------------------------
> From: "Joe  Subich, W4TV" <lists at subich.com>
> Sent: Tuesday, February 09, 2010  3:22 PM
> To: "'Tower and HF antenna construction topics.'"  
> <towertalk at 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 at contesting.com
>>>  [mailto:towertalk-bounces at 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 at aol.com>
>>> To:  <towertalk at 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
>>>>  _______________________________________________
>>>>
>>>>         
>>>  >
>>>       
>>>>  _______________________________________________
>>>> TowerTalk  mailing list
>>>> TowerTalk at contesting.com
>>>>  http://lists.contesting.com/mailman/listinfo/towertalk
>>>>         
>>>  >
>>>       
>>>  _______________________________________________
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