Re: [Amps] Glass Power Tube rebuilders

[R.Measures <r@somis.org>]

On Jun 6, 2004, at 10:33 AM, Ian White, G3SEK wrote:

> R. Measures wrote:
> > > John was clearly talking about other problems where there *was* a 
> > > need  to cut the tube apart.
> >
> > 
  It's probably easier to melt a hole than to cut the glass.
>
> That's "metalwork thinking". Glass plays by different rules.

  I used to do some glassblowing when I was taking a chemistry class.  
To make a hole in a glass tube, apply a point flame to the spot where 
one needs a hole.  When the spot is hot, blow or suck until the glass 
bubble pops.  If needed, a glass extension tube can then be attached at 
the hole by heating and sticking the glass together,
> > > Even cutting the base seal and re-attaching a pumping tube is very 
> > > difficult, because it involves using open flames close to all the 
> > > glass/metal seals.
> >
> > 
  Open flames already were used to seal the pumping tube after 
> > evacuation.
>
> The original production-line process had all the special tooling 
> required (including shields to make sure the flame didn't touch the 
> base pins) and it only involved one open-flame operation down there.

  Only one open flame operation is needed to make a hole in the glass 
and attach a glass tube for the carburization/pump-down operation.
> Re-evacuating a glass tube involves three operations, and they're all 
> riskier than anything done during manufacture.

  Pinching off a glass tube is fairly straightforward if the right 
amount of heat is applied.    The vacuums in my 3-500Zs are still 
there, so it must be do-able, Ian - even if the sky does fall on 
occasion.

cheerz
Richard L. Measures, AG6K, 805.386.3734.  www.somis.org

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