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Re: metal or non metal cross booms



I have done that in the past and it works rather well. However, PVC gets 
extremely brittle over time from UV. Be sure to give it a good paint job 
with some form of marine paint (anti-UV) to help preserve it. I used on 
for 10 years and it was still good and give it to someone once I went to 
a solid fiberglass unit. Once the PVC becomes brittle, you'll not be 
able to tighten u-bolts down very tight.

I do not remember where or who, but I bought a solid 10 foot piece of 
fiberglass boom 1 1/2 inch in diameter from a place in Ohio. Since UPS 
would only allow up to 9 feet long, the company cut 1 foot of it off and 
shipped it (including the one foot remaining). I painted it with a UV 
resistant paint and it is still in use for my KLM antennas. The unit 
cost about $35.00. Not sure what the cost would be now. You can also 
check with your local marina or marine supply for fiberglass masting of 
various sizes.

I have also used the metal boom and had the arrays at 45 degrees to the 
boom and the elements and it seem to work with little impact on performance.

Reid, W4UPD



kc6uqh wrote:
> Suggestion,
> Wood has very good strength, why not place a wood dowel rod inside a pvc 
> pipe with end caps to keep the weather out?
> THe wood will offer the support and the pvc will protect the wood from the 
> elements.
>
> Art ,
> KC6UQH
> ----- Original Message ----- 
> From: "Prathap Kumar" <vu2pop@gmail.com>
> To: <amsat-bb@amsat.org>
> Sent: Sunday, April 06, 2008 7:44 AM
> Subject: [amsat-bb] Re: metal or non metal cross booms
>
>
>   
>> Hi
>> I got the thick wall Blue PVC pipes used for plumbing wrapped in 
>> fibreglass
>> mat and its been in use for over ten years now.
>> The final OD is now about 40mm.
>> It does support both my cross yagis on the rotator.
>> I am also looking for the fibreglass tube with thick wall and hope to get
>> some here in Bangalore and will keep you informed Gopal.
>> Best 73
>> Pop
>> VU2POP
>>
>>
>>
>>     
>>> Gopal,
>>>
>>> A good decision that you made.  A study by Kent, WA5VJB, shows that
>>> only some sensitivity of position between elements on the antenna
>>> boom impacts using a metal crossboom if the antenna is mounted in the
>>> "X" confinguration.  My satellite antennas are mounted this way.
>>>
>>> 73 Ed - KL7UW
>>>
>>> At 05:50 PM 4/5/2008, Gopal Madhavan wrote:
>>>       
>>>> I have experimented with both non-metallic and metallic cross booms after
>>>> reading numerous articles on the subject some years ago. With CP antennae
>>>> mounted in X configuration there seems to be hardly any difference in
>>>> performance. I speak of experiments done when AO-40 was active.
>>>>
>>>> I now use a metallic boom as it gives very good rigidity to mount two CP
>>>> antennae, a small dish for 2.4 GHz, preamps etc. Here in India I do not
>>>> have
>>>> the option to order a good section of fibre glass cross boom any way, and
>>>> so
>>>> had made do with PVC tube wrapped in fibre glass, but it eventually 
>>>> sagged
>>>> and I had to periodically rotate it 180 degrees to keep it somewhat 
>>>> level.
>>>>
>>>> Gopal VU2GMN
>>>>
>>>>
>>>> _______________________________________________
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>>> _______________________________________________
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>>>       
>> _______________________________________________
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>>     
>
> _______________________________________________
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>
>
>   

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