[Amps] Vacuum Variable Fatigue Failures

[Pat Barthelow]

Folks,

I was looking closely at the mechanical marvel that is a Jennings Vacuum variable capacitor.
I am wondering about whether the copper bellows arrangement that allows extension and 
contraction of the "rotor" have a finite number of cycles back and forth before they are likely
to fatigue crack at the folds of the copper.  It looks scarily fragile and subject to failure with 
heavy cycling from meshed to unmeshed condition... or perhaps there is a lot more engineering
there, that I don't see to minimize that problem.  There's a reason why they are so expensive...
How many cycles, if any, before they are prone to failure?
All the best,
Pat Barthelow    (916) 315-9271
aa6eg at hotmail.com
http://www.jamesburgdish.org
Project Manager,  Jamesburg Moonbounce Team


> From: higasa at plum.ocn.ne.jp
> To: Amps at contesting.com
> Date: Mon, 11 Feb 2008 14:55:05 +0900
> Subject: Re: [Amps] SB-220 on 6 meters: looking for projects...
> 
> Joe
> I forgot a link of SB-220 for six.
> 
> http://www.iizuka-net.ne.jp/~bear-el/sb-220-6m/
> 
> GL, de Han JE1BMJ
> 
> ----- Original Message ----- 
> From: <it9blb at infcom.it>
> To: <Amps at contesting.com>
> Sent: Thursday, February 07, 2008 9:50 PM
> Subject: [Amps] SB-220 on 6 meters: looking for projects...
> 
> 
> > I'd like to convert my old SB-220 into a 6meter monoband amp.
> > After a long surfing on the web, I wasn't able to find any
> > dedicated article or complete and tested suggestions to
> > support my target.
> > Any possible good suggestion here?
> >
> > Thanks in advance for any help,
> > "Joe", IT9BLB
> >
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