Miniature wire end valve

[djrm]

The photo show a miniature wire ended valve. I don't know if it ever had any markings but it hasn't any now since it went through the washing machine by accident.
It is a directly heated triode, heater measures 4 ohms. The shape and appearance isnt quite like any I can see when I search for similar parts.
I wonder what it is, any ideas? David.

   

[Mike Watterson]

Likely the resistance is about x2 when running, so could be 1.4V 150mA, a portable transmitter valve.
I've a lot of wire ended US, UK & USSR parts and it's not like any.

[boater sam]

A special hearing aid valve?

[Ed_Dinning]

Hi David, there were types like this developed for use in anti-aircraft shells, so they would detonate when in close proximity to an aircraft. This development improve the hit rate of AA fire by a few orders of magnitude.
There was an article and other information on these in RB about 10 years ago

If you look up the valve museum (Leeds I think). there are lots of ID pictures of many types of valves

Ed

[djrm]

Thanks for the suggestions. The valve museum site is difficult to navigate without becoming a member. The AA shell application sounds interesting I'll have to look into that. David.

[ppppenguin]

You could well be right about proximity fuzes.
https://www.valvecollector.uk/cv122.htm
http://www.r-type.org/pdfs/cv122.pdf
https://military-history.fandom.com/wiki/Proximity_fuze

[Ed_Dinning]

Hi David, I have some samples of the valves and one of the shells if you are up in the Newcastle area

Cheers, Ed

[Mike Watterson]

A special hearing aid valve?

No, too high power and high consumption if sample is 4 Ohms cold. Also they used Pentodes except in 1920 & 1930s
This DF70 is typical of hearing aid type
https://www.radiomuseum.org/tubes/tube_df70.html
0.625V Vf so two in series for LT. 25mA, so about 25 Ohms when hot, likely more than 13 Ohms cold.
Maybe two 22.5V HT packs like in AVO. Or even one.

Admittedly it looks a bit similar.

Transmitter or high power oscillator on a proximity fuze is possible. Also used on bombs so that it would explode before hitting the ground rather than impact making a deep pit. I suspect fuze applications more like metal detector / Therimin circuits than actual radar.

Curiously battery powered hearing aids existed before valves!

Used a carbon mic and 2,000 + 2,000 ohm earphones. But a sound insulated capsule had a single 2,000 earpiece (driven with battery & chest mounted carbon mic) and carbon microphone (driving headset via a battery) sharing a single diaphram. Probably used 3V. A pair of old phone handsets wired in series with a 6V 996 pack using bottom and top wire of our fence was a great toy telephone. Those used carbon mic and 600 Ohm earphone.

[djrm]

Yesterday I was told they are from flying bomb 'doodlebug' destroying shells. I also found a selection of other types in a box too. The larger one is triod construction with four wires and marked CV183. Another one has five wires and looks like a tetrode, this has numbers on it . Another one is fitted in a metal tube similar to an old transistor - unmarked, again with four pins.

brief information about cv183 here:
https://www.valvecollector.uk/cv183.htm

From top: 

long 4 wires
CV183 168
CV183 173

metal 4  wires
unmarked
black dot

short five wires
green dot, UD1 559 213
green dot, UD1 559 236

   

[djrm]

Proximity fuze: https://www.navalgazing.net/The-Proximity-Fuze-Part-1