Interresting Quiz. Which tube is this?

[Radioman62]

I have got a pretty large collection with tubes as a christmas present

Several of them has unreadable labels and most of them are common TV tubes which not are that useful anyway.

But I would like some help with one type of tube which I have three of. It's a long size 9pin tube with goldplated pins and top anode which also are goldplated. It seems to be a double penthode tube. I have never come cross anything like this before.

As a challenge for all tubelovers before the new year arrive, I have taken two photos of one of the tubes and put up to see here .

Please, is there anybody recognizing this tube?

[Eli Duttman]

Are you sure that's an anode, not a cathode, cap? Is that a "normal" Noval base or is it the heavier duty Magnoval? The Russian 6Д22С (6d22s) is a Magnoval based damper diode, with a cathode cap.

[Radioman62]

Normal 9 pin and definately an anode coupled top hat.

[adalin]

EL81 or PL81

[Colt45]

Yes, looks like PL81 to me

[Radioman62]

Yes, you are probably right

PL81 it seems to be.

Thanks