[TowerTalk] Making aluminum tubes telescope smoothly, with good electrical conductivity?

[Keith Dutson]

Is it just me, or did anyone else get 6 copies of this post?

73, Keith NM5G

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Mark - AA6DX
Sent: Monday, May 09, 2005 12:15 PM
To: Kristinn Andersen; towertalk at contesting.com
Cc: 'Kristinn Andersen'
Subject: Re: [TowerTalk] Making aluminum tubes telescope smoothly,with good
electrical conductivity?

Kristinn ... here is what I would use ... FINGERSTOCK
http://www.surplussales.com/RF/RFFingerstk-1.html
----- Original Message -----
From: "Kristinn Andersen" <tf3kx at simnet.is>
To: <towertalk at contesting.com>
Cc: "'Kristinn Andersen'" <tf3kx at simnet.is>
Sent: Saturday, May 07, 2005 6:37 AM
Subject: [TowerTalk] Making aluminum tubes telescope smoothly,with good
electrical conductivity?


> Hi:
>
>
>
> I am working on an extensible vertical consisting of a 6m/18ft outer 
> aluminum tube (40mm/1.5" diameter) and an inner aluminum tube that can 
> be extended out of it with a motor mechanism.  For certain reasons the 
> inner tube has to be substantially slimmer than the outer one, 
> probably around 25mm/1" diameter.  So, to make a reasonably tight fit 
> I will make a narrowing "collar" at the top of the outer tube, where 
> the inner one will emerge upwards.  Furthermore, at the bottom of the 
> inner tube I will fasten a cylinder that almost fills the outer tube, 
> providing mechanical stability there.  Sort of like a piston inside 
> the outer tube.  Thus, the mechanical connections or interfaces 
> between the outer tube and the inner tube are at the top of the outer 
> tube and at the bottom of the inner tube.  At these key points I need 
> to ensure:
>
>
>
> a)       Good electrical contact (so that antenna currents can continue 
> from
> the outer tube to the extended inner tube;
>
> b)       Minimal mechanical friction as the inner tube is pushed up and
> retracted back down.
>
>
>
> Are there any suggestions on this?  What metal should I use that 
> slides with low friction against the aluminum tube wall, does not 
> corrode at the contact and provides good conductivity?
>
>
>
> 73 - Kris, TF3KX (http://www.simnet.is/net/tf3kx)
>
>
>
> _______________________________________________
>
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>
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_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.

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