Valves. Why glass?

[Top Cap]

Wow what a film, wish I could get my own HD copy. How much would an EL84 cost today with all that work force? At least the film shows how Glass was so easily worked, not just the envelope but also the all important glass/metal seal base. Did you see that side contact valve, bet that stirs up some memories

[repairman 1234]

Originally Posted by ampzilla

Here you can see The Blackburn Story

Wow!

What an absolutely super little film, thanks so much for putting that link on

As well as the electronics side of this i am also interested in it from a historical point too, just great, thanks!


All the best,

Chris.

[Skywave]

Wonderful! And so very educational. From now on, if anyone asks on this Forum "how were valves made", they have a fully comprehensive answer.

I didn't realise just how much human effort went into valve manufacture - despite the assistance of so much machinery. However, the sheer repetitive nature of the work on the assembly lines must have been incredibly boring. Thank goodness I missed that in my career!

Did anyone else pick up the quick reference to "glass tubes for valve or transistor manufacture"?

Thanks ampzilla for your contribution.

Al / Skywave.

[Tractorfan]

Hi all,
I agree, that little film was absolutely fascinating. What must their eyesight be like after years of assembling valves with tweezers? They didn't seem to be using magnifying glasses as far as I could tell. I feel guilty now for throwing dozens of EF80's out before we came out here.
And if you thought assembling an EL84 or EF80 by hand was fiddly, just how on earth did they make those tiny valves for hearing aids (DL70 & DF70 I think, correct me if I'm wrong).
Cheers de Pete

[Mike-repairman]

Great little film.

You wonder how they can still make valves abroad for just a fiver a time with all that work involved.

Some history of the thermionic valve on this link...
http://en.wikipedia.org/wiki/Thermionic_valve

Often makes you wonder how someone stumbled across the reaction of electricity, metal plates and heaters in a vacuum.

Mike.

[dseymo1]

Often makes you wonder how someone stumbled across the reaction of electricity, metal plates and heaters in a vacuum.

Recieved wisdom is that Fleming noted the darkening of the envelope of electric lamps after a period of use, and added another electrode to the bulb in order to investigate how this was caused. The rest, of course, is history.
(Apparently, he never did work out quite what was happening - this was left to later physicists.)

[russell_w_b]

Originally Posted by Mike-repairman

Great little film.

You wonder how they can still make valves abroad for just a fiver a time with all that work involved.

No, you don't. They're made in far-eastern gulags by people who are either grateful for their job and the pitiful reward it entails, or else they are dispatched toot-suite back to rural poverty.

I do wonder, though, if Russian valves (former USSR) were subsidised by the Soviet government, like 'Sekonda' watches and various makes of cameras/optics? They were of pretty decent manufacture and would have cost far more otherwise. Of every ten Russian valves bought for use by the BBC at Rampisham (813's, if I remember correctly), two were guaranteed duffers.

I went around the Thales valve factory at Thonon, France, in September 2003. Admittedly they only manufactured big stuff there, but it was very laid-back compared to the Mullard factory on the film!

[XTC]

It's a fascinating film and well worth watching. I was surprised at the level of automation they had and also that whatever means they used to evacuate the valves seemed to be suitable for continuous production rather than batch by batch.

Originally Posted by russell_w_b

I do wonder, though, if Russian valves (former USSR) were subsidised by the Soviet government, like 'Sekonda' watches and various makes of cameras/optics? They were of pretty decent manufacture and would have cost far more otherwise. Of every ten Russian valves bought for use by the BBC at Rampisham (813's, if I remember correctly), two were guaranteed duffers.

Before the iron curtain fell, the Russians did all sorts of things to gain hard currency, such as mining gold from deposits which wouldn't have been thought worth the effort in the West. Maybe the valves were the same.

Z&I Aero Services sourced valves from all over the place, but a lot of the valves and electronic equipment they sold was from the USSR.

Also, when the MIG 70 pilot defected to Japan with his plane, I think in the late 70s, the electronics were all valve. Maybe the USSR didn't have the solid-state technology, however, it was pointed out that the plane's avionics being valve based. were resilient to EMP. EMP resilience was why we kept some RA17s ready for service for years after solid-state had matured to the point where it could replace the RA17.

I believe it was the same with the R390A with the Americans.

There was a story on one of the R390A sites that there' s a small manufacturing plant in Georgia which is fired up every now and then to produce runs of new valves for the remaining valve equipment in US government service.

Pete.