For Sale: 19 Set Spare Valve Box

[BCA]

Going back to the cloth socks: maybe they were to prevent finger prints contaminating the glass surface. Lighting technicians are very careful not to leave finger prints etc when changing high power light bulbs. The contamination may affect the glass. I think halogen bulbs in typical work lights are to be handled carefully too.

[Chris Suslowicz]

Originally Posted by BCA

Going back to the cloth socks: maybe they were to prevent finger prints contaminating the glass surface. Lighting technicians are very careful not to leave finger prints etc when changing high power light bulbs. The contamination may affect the glass. I think halogen bulbs in typical work lights are to be handled carefully too.

You're thinking of Tungsten/Halogen (Quartz/Iodine) lamps which have an envelope of fused quartz that is badly affected by contaminants (e.g. skin oils) which absorb more heat than the rest of the envelope. The resultant hot-spot can cause the quartz to change to a crystalline form (which is much weaker) and also leak gas. (It can also weaken the envelope and cause it to shatter or explode due to the internal pressure.)

(If you get fingerprints on a Tungsten/Halogen lamp when changing it,you need to carefully clean the contamination off with an alcohol-soaked cloth before using it.)

It's very unlikely to affect vacuum tubes, even the early silica-envelope high power ones used by the Navy, as I don't think they ran nearly hot enough for that to be a problem. (Then again, it must be a couple of decades since I last looked in the Admiralty Handbook of Wireless Telegraphy!)

Best regards,
Chris.

[BCA]

Thank you Chris for the detailed explanation. It prevents my theory from becoming another mistaken “urban legend”. .. Brian

[r.morrison]

Yes and after all that.....the spare valves/tubes box remains UNSOLD!
Cheers: Robert

[Chris Suslowicz]

Originally Posted by r.morrison

Yes and after all that.....the spare valves/tubes box remains UNSOLD!
Cheers: Robert

I can't help with that, I'm afraid, I'm on the wrong side of the Atlantic Ocean and about as far away as it's possible to get from you without leaving the UK.

(About a third of the way around the planet, given that I'm at 1 degree West and BC is at 125 degrees West (according to Wikipedia).)

I've also got enough spare valve cases for my sets (plus bulk purchased valves when various people sold off surplus stocks of the ones I might need).

(The skyrocketing price of international shipping is also something of a blocker - I remember importing a couple of reasonably complete WS19s from the US and Canada - I couldn't possibly afford to do that now, with the steep rise in idiot pricing on eBay and the punitive shipping rates (plus probable import duty, etc.).)

Please accept my apologies,

Chris.