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Unknown Transmitter Valves?

Jacob Roschy Ernst Erb Martin Renz Bernhard Nagel 
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Forum » Valves / tubes - Semiconductors » Very rare valves or unknown (not in RMorg) » Unknown Transmitter Valves?
Oliver Harlow
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16.May.14 17:12

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Hello everyone,

First, I must say that I am a novice in all things to do with valves and radios. One of my "jobs" at The National Museum of Computing here at Bletchley Park is to sort through boxes and boxes of donated valves and components cataloging and identifying ones that we definitely need to maintain our computers and others that we might exhibit, or, at some later time, sell on to raise funds for the Museum. All with the permission of the original donors.

Among the collection we have two particularly large valves that I am informed are Transmitter Valves, however there are no identifying marks remaining on either. Do any of you real experts recognise them, please?

The first ("Valve A") is 280mm high, the maximum glass diameter is 90mm (excluding side connection) : picture attached

The second ("Valve B") is 240mm high and 115mm diameter : picture attached

I hope this is the right place to post this.

Many thanks

Oliver Harlow,

Volunteer, The National Museum of Computing, Bletchley Park, Milton Keynes, UK



Götz Linss † 27.06.21
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17.May.14 00:49

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 Hello Mr. Harlow,

valve (B) - second picture looks very much like an EIMAC 4-1000A or one of its derivatives. Mine has the same height as yours but slightly larger diameter of 127 mm.

Greetings Goetz Linss


This article was edited 17.May.14 13:23 by Götz Linss † 27.06.21 .

Oliver Harlow
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17.May.14 17:29

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Thank you very much, yes, so it would appear to be. I re-measured the diameter a bit better with some calipers and it is 127mm, you are correct.

This one will go on exhibit as an interesting valve example as looks rather burnt out. There is a blackened dimple in the glass and the fins assembly has some melted holes at that point.

One down, one to go! Anyone seen anything like Valve "A"?



Dietmar Rudolph
Dietmar Rudolph
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17.May.14 21:23

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Valve A looks very much like being gas filled.

If you have a Teslator ad hand you can check this very easily.

If the valve has a gas filling, it might be a Thyratron.



Emilio Ciardiello
Emilio Ciardiello
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18.May.14 07:51

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Hello Oliver,

the unknown valve A looks to be a mercury thyratron PL105 made by Philips and by Philips related brands.


Oliver Harlow
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18.May.14 13:49

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@Dietmar: No, sorry, we don't have a teslator. Interesting!

@Emilio:  Yes, That definitely looks like it. Thank you very much! If we put this on exhibit I'll need to make a stable base for it one day, so for the moment it'll go back into store.

Thank you all, that's my questions answered - very quickly indeed!