This is a big valve but what is it? [4212 or V1505]

[The General]

Here's a bit of a poser...
I bought this big valve last year at a steam rally with the intention of mounting it on a hardwood base as a display piece... but what is it?
It stands 10" high not including the pins & is 3 1/2" diameter.
It's a directly heated power triode with a heavy anode, the heater looks about right on 6.3V & takes 4.3A.
The two getters appear to be unfired & there's no type number on it. There is a slight flaw in the glass so I think it's a production reject.
Someone has written 19-1-76 on the base which I assume is a date.
So what is it? Sorry there's no prize for the winner but if anyone knows, I'd love to know.......
Cheers,
Mark.

[Ed_Dinning]

Hi Mark, it looks a little like the 813 (big brother to the 807, but this one hasn't a top cap.

There were many power valves like this used in industrial vibrator amps and the reddiffusion "wired sound" system.

Ed

[PJL]

Probably a relative of this http://www.r-type.org/exhib/aaa0287.htm. A massive PA output valve for an AM transmitter.

[Top Cap]

It's an ITT 4212H or an earlier 4212E

http://www.r-type.org/exhib/aaa0287.htm

I have one if you ever decide to build a 500W per channel stereo amp

Nice solid graphite anodes, they light up lovely.

Les

[Sean Williams]

I think Mike Barker was planning to build an amplifier with these....

Glad I don't live next door.....

Sean

[Skywave]

Originally Posted by Ilikevalvesme

. . . the heater looks about right on 6.3V & takes 4.3A.
Mark.

Originally Posted by Top Cap

It's an ITT 4212H or an earlier 4212E

http://www.r-type.org/exhib/aaa0287.htm

Les

Les - I'm sure you're correct, but I note that Mark does say that the heater is 6.3v / 4.3A; the 4212 is 14.0v / 6.0A (according to the WebSite above ).

Mark - how do you know that the heater voltage / current of your specimen is as you state?

Al. / Skywave.

[AlanBeckett]

Al/Mark,
Hmmmm.
Tungsten has a big positive temperature coefficient so 6.3v/4.3A might equate to 14v/6A. Being a thoriated filament it will be pretty bright.
Perhaps you could mount it under a glass dome witha few volts on the anode just to show it off
Alan

[The General]

Originally Posted by Skywave

Mark - how do you know that the heater voltage / current of your specimen is as you state?

Al. / Skywave.

Ahh, not very scientifically I'm afraid, Al. I just wound it up on my bench psu from zero & stopped when the filament looked red/orange & about right. This was at around 6V so I guessed 6.3V.
Mark.

[murphyv310]

Hi
I did think it was a valve used on British Relays kilowatter's (audio amps) but in retrospect I think they are a tad too small.
They certainly are beefy probably good for 200w +
Cheers
Trevor

[Skywave]

Originally Posted by Ilikevalvesme

Ahh, not very scientifically I'm afraid, Al. I just wound it up on my bench psu from zero & stopped when the filament looked red/orange & about right. This was at around 6V so I guessed 6.3V.
Mark.

My, you're a brave man! You could have blown that filament - for example, if it was 4v.

Thanks for the reply, anyway. I was just a little puzzled, since your figures clashed with Top Cap's.

Al./ Skywave.

[AlanBeckett]

Al,
.... but hasn't everyone been there at some time?
My PhD is as good as anyone's in hindsight.
The real story is that at some stage of a project someone has to say 'that's it, we'll switch it on', and accept the consequences. The only snag is , that's generally the Engineer in charge
Alan

[Skywave]

Yes, Alan, that's fair enough - as far as it goes. In the scenario you mention, there has usually been some data analysis / R & D / design procedure & notes studied beforehand that reveals at least a narrow range of parameters prior to applying such a drastic test. For example, take an old, unknown radio, which I suspect is not a nominal '240-v.a.c.' device. I'm not going to automatically assume it's '240-v.a.c.' and plug it in - it may be 115-v - or anything! Agreed, a Variac / lamp limiter should be used under these circumstances, (failing the lack of any definite, reliable info.), but with the item in question in this Thread, would such a limiting be adequate? For myself, I wouldn't risk it, but would try to get some info. first - for example, asking on this Forum.

I suppose it all boils down to one's attitude to risk; I'm a rather cautious type. .

Al. / Skywave.

[AlanBeckett]

Al,
I'm cautious as well.
Mark said (above) that the getters hadn't been fired so it's probably a reject.
I think the real question is 'do you want to use it or display it?'
I'm in favour of use, but if putting 14v on the heater is going to kill it then I'm in favour of sending it to the Valve Museum.
Re the side subject of who carrys the can, all I can say is that I've stood on an American coal face and pressed the 'Big Green Button', and hoped that 2 MW ( Yes that's a big M) of machinary would start up, and stop when someone hit the red buttons.
The old salesman I used to work with called it 'putting your knob on the block'
Alan

[Top Cap]

Well I have not tried any heater supplies on my specimen but the guy who gave it to me said that when in use it lit up like a light bulb. I guess it takes some stick when you consider the elaborate spring mechanism to absorb the expansion of the filaments. I found this particular valve extremely useful at instructing young students into the construction of a valve. The grid is so clearly seen wound around the heaters inside the big graphite Anode.
I in fact had two of these valves, the other one suffered minor damage (loss of solder from its pins) during an intense fire at the place it was stored. I lost countless NOS valves like GZ32's, 6L6's and EL34's all subjected to so much heat that their glass envelopes melted. However the giant triode survived all that, the envelope must be very high temperature glass.

[ppppenguin]

Originally Posted by AlanBeckett

...
Mark said (above) that the getters hadn't been fired....

I'm not sure that all big power valves had getters. Got a funny feeling that the conditions in the valve were too harsh to allow them to work properly. Or I may be talking rubbish.

[murphymad]

I have a number of these valves.

It's as said above a 4212 or V1505 (same thing really).

When the filament is given its full voltage (and it needs to be) they light very brightly indeed.
None of my examples have a getter, as Jeffrey rightly states why.

They were used as industrial valves for large power applications both in factory/site public address systems covering vast areas or for power control and regulation.

They will deiliver several hundred watts of audio power with the right circuitry, power supply (which is no mean job!) and a very serious output transformer.
They will also need driving correctly otherwise you are just using units of electricity for a pretty room heater. Boy do they run hot!

It would be a terrible shame to just use it as an ornament, especially if it's not a dud.

Mike...

[GrimJosef]

This valve is comparable in performance, although different in physical construction, to the 304TL. To get some idea of what's involved in making an audio amp out of one you could look here for a single-ended design http://www.alumrocktech.com/amplifier.shtml When you check out the prices of the transformers you'll know why murphymad winds his own !

I'm guessing most people will think that's a bit pricey for a 30W amp . So let's assume you're prepared to buy a second valve and then you can run a push-pull design. If you didn't want to build from scratch you might well be able to modify one of these http://www.amberwaveaudio.com/the304TL.htm Now you can have a couple of hundred watts (bear in mind that the amp will weigh 200lbs though, so you might have to spend a bit on shelf reinforcement). The quoted distortion figures are, by modern standards, dreadful (but probably still only just audible). However I imagine they could be fixed with a bit of negative feedback, provided there was enough gain in the driver stages.

Cheers,

GJ

[Skywave]

This valve sounds like a good candidate for a substantial regulated power supply, in which it is used as the series pass valve.

Al. / Skywave.

[The General]

Hmm, thanks for the input, chaps. It certainly seems similar (at least, visually) to the AEI V1505 on the National Valve Museum's website.
As Mike says, it would be a shame not to use it (although it would of course need a serious power supply & output transformer) but it does have a flaw in the glass which is a spiral mark running around the bulb. Possibly it was rejected because of this & never marked with a type number or used. Certainly the pins have no marks on them & the internal parts seem too bright for a valve which would have been run at such a high temperature.
There are two ring shaped elements inside which I must say look like getters, you can see one in the first photo on my original post.
I have it in my grubby mitts now & I'll try to photograph the flaw but I'm not sure if will be visible.
Cheers,
Mark.

[Top Cap]

I always thought those ring elements were for radiating heat away, but they are attached to adjacent anode supports so perhaps not. I have seen these valves used for driving a giant transducer on a vibration test rig.