Mullard, Blackburn.

[threeseven]

This might also be of interest. It is part 1 of a series, the additional parts and others of interest can be seen.

http://www.youtube.com/watch?v=xnvKCC6_VDQ

[McMurdo]

"The finished grids are placed into trays and passed to an Inspectress".

This caught my ear, lovely.

[threeseven]

Yes, I noticed that too !!! The world was a very different place then !

[murphyv310]

Sad it's all but gone now!!

[threeseven]

Having never seen the manufacturing process for valves before I was amazed at the intricacy and complexity of the machines that formed and assembled the components and the final valve.Also the accuracy and quality is very impressive. The only things not shown was marking and packaging.
Imagine how much valves would cost now if still being manufactured by those methods ??!!

[andyb_83]

Very impressed by the level of automation on the various production lines back then, designing the control systems to do some of those jobs would be quite a big task even today!

[Pamphonica]

...not a single robot in sight. Just some excellent sequential processes based almost entirely on cams and hydro-mechanical actuators, I assume. A delight to watch for anyone who loves beautifully-designed machinery. Thank goodness this film survived.

[Radio_Dave]

I'm pritty sure this film was originally put on the internet by that company of ex Mullard employees (Techtube I think) who started up production on the old Blackburn site, a couple of years ago?

Anyhow, I always wanted to ask them if they could make a modern version of that film and put them both on their website.... Unfortunately they seem to have gone the same way as their ancestors

[Mullard]

I worked at the Mullard works in Blackburn in 1967, initially in the Pre-Production and Factory Assitance department, and then in the Technical Department. I well remember the manufacturing processes. Most valve assemblies were made at the feeder factories and returned to Blackburn for pumping. I made many trips out to run experiments on new materials and components. I also remember the in-line machines that were used to make ECC82/83s and EF183/184s. Each assembly position had a slide-through bolt which was move across if any problem was detected at any stage. If the bolt was across, action at subsequent stages was inhibited. It didn't always work, and the result was a very distorted assembly which was then thrown out at the end of the line. It soon became clear that the valve was on its way out, and so I pursued a career in computing instead. This turned out to be a very good move!
John

[threeseven]

Assuming we accept say 1904 as the first use in application of the thermionic valve and that they were obsolete by say 1974, well at least thats when TV's became virtually all transistor, the valve was still in use longer than the semiconductor has been to date !!
Thats pretty amazing !
I'm now slightly ashamed of my opinion of valve technology when I first became involved in electronics ! My friends, colleagues and I would just laugh at the crapness of valves compared to the emerging IC technology !
Now although valves cannot really be considered as anything other than obsolete technology now, they still hold the accolade of being the dawn of electronics and therefore hold a place of reverence.
My fascination for the things has developed strongly over the past 10 years and I just so regret not absorbing more of their hay-day before they disappeared from the mainstream.
What I find most fascinating is that the operation of the device is almost totally visible, if only electrons were visible !!
I wonder if any of that Mullard plant survived to a museum ?

[julie_m]

Originally Posted by threeseven

What I find most fascinating is that the operation of the {valve} is almost totally visible, if only electrons were visible !!

Indeed; but electrons really are tiny, tiny little things -- probably too small to fit into the human imagination. A current of one ampere is equivalent to 6 241 509 479 607 718 383 electrons per second (six million million million). All the electrons displaced by that amount of current flowing for 50 hours solid (180 000 seconds!) would weigh just over a milligram.

Originally Posted by threeseven

{T}he valve was still in use longer than the semiconductor has been to date !!

Not by much, though. The first transistor radio was the PAM 710, launched in 1956; so it will take until 2026 for semiconductors to have had the same 70 year lifetime as valves.

That being said, it's difficult to imagine anybody inventing the transistor without there first having been such things as valves .....

[threeseven]

Thanks for that quantification, an incredible factoid !!
Just trying to imagine those electron streams within the glass envelope of a valve during operation is mind altering !
One of my cherished recollections of valves is a visit to Holme Moss transmitter in my Uni days. Seeing the output valves on full output was an impressive sight even for a (then) valve skeptic ! Although my recollection has faded slightly, I seem to remember they were water cooled.
The duty engineer expended great emphasis on the dangers of high power RF and the nature of RF burns. I was very fascinated by the wave guides connecting them to the mast.
We were all quite humbled by the experience !