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.
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.
Re-evacuating a glass tube involves three operations, and they're all
riskier than anything done during manufacture.
--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
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