Tube ID

[Rmac587]

Hi Folks,
A typical tube mystery.... the usual tricks haven’t worked. I beleive it is a Phillips/ Bugle, bit can’t be sure.

looks to have “B501” and “164” on side of glass.
There is an “A” on bottom.

Memory is fuzzy, but it may be a Scott 330 6xxx tube. I’m hoping more a 12ax7 however.

 

[GordonW]

The way to tell if it is a 6xxx vs a 12xx7, is to measure for resistance between pin 4 and pin 9, and between pin 5 and pin 9.

If you get a low impedance that is the same between measuring 4-9 and 5-9, and double that impedance if you measure between 4 and 5, then it's almost undoubtedly a 12xx7.

If you ONLY get continuity between 4 and 5 (no continuity to pin 9), then it's a 6xxx tube.

Regards,
Gordon.

 

[madwing]

and it looks to be a mullard blackburn tube, not phillips/bugleboy.

 

[Dswankey]

Hi Folks,
A typical tube mystery.... looks to have “B501” and “164” on side of glass.
There is an “A” on bottom.

I wanna say it is a 12AX7, the I6X denoting short plate made in the Philips owned Mullard factory in Blackburn GB however seeing as the HH Scott 330 didn't use 12AX7's maybe it is on of the 6XXX's you mentioned

http://www.tube-classics.de/TC/Tubes/Valvo ECC83/ECC83.htm

 

[Dswankey]

12AU7?

http://www.tube-classics.de/TC/Tubes/Valvo ECC82/ECC82.htm

 

[buickguy62]

I64 indicates it's a 12AX7, 4th revision, B indicates Mullard Blackburn, I'm guessing 501 is some indication of the date,

 

[Rmac587]

This is all great information. I was reading the I as 1...
I’ll double check using @GordonW’s technique. I can at least narrow it down.

Thanks All!

 

[Rmac587]

I wanna say it is a 12AX7, the I6X denoting short plate made in the Philips owned Mullard factory in Blackburn GB however seeing as the HH Scott 330 didn't use 12AX7's maybe it is on of the 6XXX's you mentioned

http://www.tube-classics.de/TC/Tubes/Valvo ECC83/ECC83.htm

Thanks D! I may have the wrong model or unit, but should be able to solve it using Gordon’s method.