Hi to All, Sweitzel,
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Hey everyone! Any new news from France on the rebuild efforts?
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Recent update:
10x 15GP22s currently at RACS. A first batch of 4 tubes is undergoing the frit process. This is very time consuming: 4x frit applications & 4x cooking cycles are necessary per tube to seal the two glass to metal welds, fore and aft of the metal anode ring + a 5th frit pass on the outer rim of the metal anode.
see diagram supplied courtesy of Bob G./John F.jr/J.Yurkon
Since mid Oct, various tweakings of the frit formula have been tested to optimize smoothness and adherence.
Once the first 4 glass envelopes have been completed, partial vacuum testing will be done without a gun. Until the envelopes prove to be totally airtight, no use risking to spoil a rebuilt gun - 16 man/hours of work per tri-color gun.
Other CRT activities:
Nick (Miniman 82) built himself a B&W CRT (10BP4 type) from A to Z using NOS glassware found at RACS. The CRT is now with Nick in WI and hopefully should soon be installed in a TV chassis at the ETF.
NOS 12" glassware is planned to be used to make "repro" Mazda CRM-121's for the UK. This is a Pre-War Pyrex tube.
RACS's partner SIVE is assessing the possibility to build repro Pyrex tubes from scratch. The principle is to fold over a very large Pyrex cylinder to make the screen at one end, then fuse a much thinner diameter tube at the other end to make the neck. From the industrially available Pyrex cylinders, max screen size would be limited to 9 inches.
A transparent vessel already made using this technique is due to be sent to RACS to assess the screen's optical flatness once covered with P4 phosphor.
Some genuine Pre-War Pyrex tubes which exhibited micro-cracks and cracks around the final anode button have been sent to SIVE for Pyrex reflow (Darryl's 12AP4 for instance).
Gun rebuilds: RACS rebuilds them, but one man only is a slowdown for volume quantities, therefore looking for partners.
Contacts are being made with E-Beam (USA), Southwest Vacuum (are they still doing them?) and Thomas Electronics - we found out they have a plant in France. We had high hopes about an ex-Philips plant in Holland, alas it closed down in July.
I called RACS today and asked for a totally up to date report. Should have it tomorrow, with photos promised of the fritted 15Gs.
Best Regards
jhalphen
Paris/France