For Sale: 19 Set Spare Valve Box

[Chris Suslowicz]

Originally Posted by r.morrison

You know Chris, the package arrived with no damage to the box and the tube was packed very well inside. I didn't check the tube over all as it looked fine to me. But it came on for a nano second and then POOF ...it went dead. This tube to buy in the USA is $100.00 plus, plus shipping. The one in Ukraine was $10 bucks. As the saying goes..."sometimes too good to be true!"
Cheers....Robert

Sounds like a heater short.

Which valve/tube was it? (I tend to stockpile spares for the sets I have.)

Best regards,
Chris.

[r.morrison]

Chris: Thanks for the offer, but I think we're talking 2 different radios. The one I'm referring to a Telefunken 5080 and it's the "Magic Eye" valve. I'll dig out the code number of you want.
Many thanks......Robert

[Chris Suslowicz]

No Need: I don't have any Telefunken valves in the parts collection, I'm afraid, so definitely can't help with that one.

Chris.

[Bob Carriere]

.....I might have a few.....

They were so nice to help with tuning the station right on!!!!

Wonder how many MLU members have ever actually used one!!!!!

Bob C

[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