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
>> > _______________________________________________
>> >
>> >
>> >
>> > _______________________________________________
>> > TowerTalk mailing list
>> > TowerTalk@contesting.com
>> > http://lists.contesting.com/mailman/listinfo/towertalk
>> >
>> >
>>
>>
>> _______________________________________________
>>
>>
>>
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