Mystery triode

[djrm]

I visited the local radio rally this morning and came home with this mystery valve as a curio.
It looks like a directly heated triode in an unusual wire ended configuration, no idea what it could have been used for.  The wire connections seem to be mainly missing from inside the cloth braid coverings but may be accessible with some cutting of the braid.

   

I wonder what its intended purpose was, any ideas?
Kind regards, David.

[chriswood]

What a fascinating find I don't know its origins but it has a very early look about it, could it be an Audion?

Chris

[Mike Watterson]

Maybe testing a vacuum pump?

[ppppenguin]

This looks far too late for an Audion. The pinch and general construction are recognisably fairly modern. It could be anything from 1930s onwards.

Mike may be on the right track, an experimental device, something made for a specfic test. Mullard, MOV etc would have made all sorts of lab lash-up devices. Very few of these would have escaped into the outside world.

[djrm]

One strange thing is that there is no getter visible - the fabric braid make it look old but I really don't know. Its well make with double welds inside the vacuum pinch sections. Apparently the central section will be tungsten to get the best possible leak proof seal.

[ppppenguin]

If it was an experiment they may not have bothered with a getter. One of the jobs of a getter is to absorb any gas emitted by the glass and electrodes over the life of the valve.

[djrm]

What a fascinating find I don't know its origins but it has a very early look about it, could it be an Audion?

Chris

Looks like you are right Chris. Found this online and it looks the same:
http://www.museumoftechnology.org.uk/obj...hp?key=879

Kind regards, David.

[PerdioPal]

Does it work, that is what all valves should do! Fascinating item, well over 100 years old. If it were mine I would make a "one valve regen" out of it for fun.

[djrm]

Does it work, that is what all valves should do!  Fascinating item, well over 100 years old.  If it were mine I would make a "one valve regen" out of it for fun.

For starters the heater(s) look intact but the wire connections are not visible but may be exposed inside the cloth braid. One braid is missing and a wire end is definitely ok to connect to. I'd like to make a one valve regen set - it would remind me of the one I had as a boy for a bedside radio. (it may have had a seperate audio amp ECL80 or something) The RF valve was probably an EF80 or similar. I do remember it having tuning and reaction condensers, one of the caps was one of those poor brown solid dielectric types available with a pocket money budget, I think the main tuner was salvaged from some other radio.

An early application here: 

https://antiqueradios.com/forums//viewtopic.php?f=11&t=330484&view=next

[Mike Watterson]

Looks like you are right Chris. Found this online and it looks the same:
http://www.museumoftechnology.org.uk/obj...hp?key=879

That site is unreliable. You'd need a more definitive source:
https://www.radiomuseum.org/tubes/tube_audiotron.html

It certainly looks similar to the Cunningham AudioTron.