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Valve recognition

Posted: Thu Aug 13, 2020 3:38 pm
by Saxman
Hi All
To you knowledgeable valve guys I have what I think are two ecc83 but not sure what they are. The printing has gone from the glass except for two numbers which is a 12 and 340 underneath it.
The tips of the valve are painted red and green.
The getter is a O getter with one support.
Two mica spacers with 17 mm plates which are grey ribbed with two slots and one hole on each side of the plates.
The only other identification marks are one valve has a T embossed on the base the other a J.
Any ideas anyone
Thanks
Alan

Re: Valve recognition

Posted: Fri Aug 14, 2020 9:22 pm
by Fran
9 pin base?

The only other thing you can do is check resistance between pins - heaters should show lowish resistance which might put you in the family at least...

Re: Valve recognition

Posted: Sat Aug 15, 2020 8:58 am
by Saxman
Fran
Thanks what would be the difference between a ecc83 and ecc82 in respect of higher or lower voltage.
I could put them in the pre amp and try them by listening to the volume levels but reluctant to do that in case I damage something.
Cheers
Alan

Re: Valve recognition

Posted: Sat Aug 15, 2020 9:02 am
by Saxman
Hi Fran
I meant resistance in ohms not voltage to early
Cheers
Alan

Re: Valve recognition

Posted: Sat Aug 15, 2020 7:50 pm
by Fran
The resistance will be the same across the heaters whether its 12ax7 or 12at/au/xx7. But at least you'd know that the pin out is pretty sure to be correct. I've heard people advise before to put one in on one channel and if the volume is lower then you know its a 12at7. No matter how you do it that feels risky though.

I also heard people saying if you put it in the freezer for a little while, then take it out, as it fogs up it often will show the lettering, or where the lettering has been.....

Re: Valve recognition

Posted: Sun Aug 16, 2020 4:18 pm
by Saxman
Thanks Fran will try the freezer option

Re: Valve recognition

Posted: Tue Aug 18, 2020 4:36 pm
by Saxman
Ah well that never worked will send details to valve distributor in UK see if I get any response

Re: Valve recognition

Posted: Tue Aug 18, 2020 6:19 pm
by Diapason
Gotta say I'm intrigued here. Don't think I'd go sticking them into anything though!

Re: Valve recognition

Posted: Tue Aug 18, 2020 9:26 pm
by Saxman
Not going to somebody somewhere must know what they are though

Re: Valve recognition

Posted: Tue Aug 18, 2020 9:28 pm
by Diapason
You could try emailing Brent Jesse?