[amsat-bb] I: Re: metal or non metal cross booms

6 Apr 2008

      Hi all,
Another solutions : (I did it)
Metal cross boom with, at the end of both side, 400 mm. of nylon shaft
Inside. It works great !
73" Frank
IW4DVZ
-----Messaggio originale-----
Da: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] Per conto
di kc6uqh
Inviato: domenica 6 aprile 2008 19.05
A: Prathap Kumar; amsat-bb@amsat.org
Oggetto: [amsat-bb] Re: metal or non metal cross booms
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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[amsat-bb] I: Re: metal or non metal cross booms

Francesco Grappi