Trying to ID an old valve - UK Vintage Radio Repair and Restoration Discussion Forum

Billy T · 17th Sep 2008, 1:43 am

Hi All

I have a direct heated triode that I purchased in a job lot of used valves and it is stubbornly resisting identification. I have searched extensively over several months by every means at my disposal but without success, and posted a number of queries on valve-specific sites but to date have not had any response, so I am now hoping that somebody will simply recognise the type and be able to fill in the details. This is what I know so far:

From residual details on the glass, I know for certain that the type number started with 10E/ and I am pretty sure that the first number following the forward slash was 4 or 7, or possibly a smeared-sideways 1. I have tried all the usual tricks to reveal further numbers but without success and there are no other markings on the glass, base, or internally.

To the best of my knowledge the following description is accurate, but I am open to correction:

Battery triode valve with inverted V oxide-coated direct-heated filament/cathode under spring tension from top with a three-panel bright metal anode.

Mini-ST12 bulb
Total length including pins 3¼" / 8.5cm total height
B4 Franco-British 4-pin base with sprung contacts
Pin length 5/8" / 1.5cm
Black bakelite base 1" / 2.5cm dia, 15/16ths / 2.4cm high
3/16 / 5mm high lip around the top of the base where it meets the bulb

There is a limited area of silver gettering residue at the bottom of the bulb.

The closest example I have found on the Web is the VT50 or 10E/10945 triode, found at www.tubecollector.org/vt50.htm The base of this valve is identical and the height is the same, but the bulb and anode structure are quite different.

Any help you can offer would be greatly appreciated, including referrals to any collectors likely to be familiar with the 10E/ types. I'm guessing, but I think that in their day the 10E/ series were exclusively for military use.

Cheers

Billy

GMB · 17th Sep 2008, 9:48 am

The 10E/ number is the Air Ministry stores reference number, the valve would have had a number in it's own right most likely starting with VT, VR or later CV.

It might help to narrow it down if you knew whether it was a 2V or 4V filament.

Billy T · 18th Sep 2008, 10:40 am

Quote:

Originally Posted by GMB

It might help to narrow it down if you knew whether it was a 2V or 4V filament.

It is a 2 volt filament. It closely resembles an HL2K, and may in fact be one, but the lack of a Maker's name or any other ID kinda complicates matters.

Cheers

Billy

Brased · 18th Sep 2008, 3:48 pm

It looks identical in structure and size to a VT50 I have just checked. This is also marked 10E/10945 and has a broad arrow followed by 2.1Z, although I don't know what the latter signifies. The RAF used a lot of these. The filament resistance (cold) is 4.2 ohms.

Edward

GMB · 18th Sep 2008, 5:08 pm

Yes, I agree that VT50 is probably what it is.

PJL · 18th Sep 2008, 10:08 pm

http://www.r-type.org/exhib/aab0077.htm

Billy T · 18th Sep 2008, 11:59 pm

Ok, I'm absolutely convinced you are right too.

I found yet another image, and after some playing around with gamma manipulation (Irfanview is great for correcting poorly exposed images or sharpening up detail and it is a free download), I think it gives a better view of the anode structure than the VT50 photo and that confirms it for me. There is a minor difference in the mica support at the top of the electrode structure, but that would simply be a manufacturer's preference so from my perspective the mystery is solved.

In researching vintage items, a great deal of importance seems to hang on which direction you go through the equivalents/alternative manufacturer tree. Go down the wrong branch and you can miss the image you really needed, and that's what hung me up, I'd found many apparent hits with the wrong bulb shape or different internal structure and never hit the right branch!

Thank you for your input, it is much appreciated. It is now labelled and on the shelf!

Cheers

Billy

17th Sep 2008, 1:43 am	#1
Billy T Retired Dormant Member Join Date: Feb 2008 Location: Auckland, New Zealand Posts: 631	Trying to ID an old valve Hi All I have a direct heated triode that I purchased in a job lot of used valves and it is stubbornly resisting identification. I have searched extensively over several months by every means at my disposal but without success, and posted a number of queries on valve-specific sites but to date have not had any response, so I am now hoping that somebody will simply recognise the type and be able to fill in the details. This is what I know so far: From residual details on the glass, I know for certain that the type number started with 10E/ and I am pretty sure that the first number following the forward slash was 4 or 7, or possibly a smeared-sideways 1. I have tried all the usual tricks to reveal further numbers but without success and there are no other markings on the glass, base, or internally. To the best of my knowledge the following description is accurate, but I am open to correction: Battery triode valve with inverted V oxide-coated direct-heated filament/cathode under spring tension from top with a three-panel bright metal anode. Mini-ST12 bulb Total length including pins 3¼" / 8.5cm total height B4 Franco-British 4-pin base with sprung contacts Pin length 5/8" / 1.5cm Black bakelite base 1" / 2.5cm dia, 15/16ths / 2.4cm high 3/16 / 5mm high lip around the top of the base where it meets the bulb There is a limited area of silver gettering residue at the bottom of the bulb. The closest example I have found on the Web is the VT50 or 10E/10945 triode, found at www.tubecollector.org/vt50.htm The base of this valve is identical and the height is the same, but the bulb and anode structure are quite different. Any help you can offer would be greatly appreciated, including referrals to any collectors likely to be familiar with the 10E/ types. I'm guessing, but I think that in their day the 10E/ series were exclusively for military use. Cheers Billy Attached Thumbnails

17th Sep 2008, 9:48 am	#2
GMB Dekatron Join Date: Aug 2003 Location: near Reading (and sometimes Torquay) Posts: 3,095	Re: Trying to ID an old valve The 10E/ number is the Air Ministry stores reference number, the valve would have had a number in it's own right most likely starting with VT, VR or later CV. It might help to narrow it down if you knew whether it was a 2V or 4V filament.

18th Sep 2008, 3:48 pm	#4
Brased Hexode Join Date: Mar 2005 Location: London, UK. Posts: 318	Re: Trying to ID an old valve It looks identical in structure and size to a VT50 I have just checked. This is also marked 10E/10945 and has a broad arrow followed by 2.1Z, although I don't know what the latter signifies. The RAF used a lot of these. The filament resistance (cold) is 4.2 ohms. Edward

18th Sep 2008, 5:08 pm	#5
GMB Dekatron Join Date: Aug 2003 Location: near Reading (and sometimes Torquay) Posts: 3,095	Re: Trying to ID an old valve Yes, I agree that VT50 is probably what it is.

18th Sep 2008, 10:08 pm	#6
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Trying to ID an old valve http://www.r-type.org/exhib/aab0077.htm

18th Sep 2008, 11:59 pm	#7
Billy T Retired Dormant Member Join Date: Feb 2008 Location: Auckland, New Zealand Posts: 631	Re: Trying to ID an old valve Ok, I'm absolutely convinced you are right too. I found yet another image, and after some playing around with gamma manipulation (Irfanview is great for correcting poorly exposed images or sharpening up detail and it is a free download), I think it gives a better view of the anode structure than the VT50 photo and that confirms it for me. There is a minor difference in the mica support at the top of the electrode structure, but that would simply be a manufacturer's preference so from my perspective the mystery is solved. In researching vintage items, a great deal of importance seems to hang on which direction you go through the equivalents/alternative manufacturer tree. Go down the wrong branch and you can miss the image you really needed, and that's what hung me up, I'd found many apparent hits with the wrong bulb shape or different internal structure and never hit the right branch! Thank you for your input, it is much appreciated. It is now labelled and on the shelf! Cheers Billy Attached Thumbnails