Another Mystery Valve - UK Vintage Radio Repair and Restoration Discussion Forum

Herald1360 · 28th Mar 2020, 8:16 pm

Found this one today whilst having a bit of a tidy up in my workshop.

IO base, pin 6 missing. Looks like maybe a diode-triode with top cap grid. Seems to have the usual 6.3V 0.3A heater on pins 2&7.

Only marking I can read is a faint "2K2 " about half way up the envelope. Can't see if there ever was more. It's not a Klystron!

Any bright ideas?

turretslug · 28th Mar 2020, 8:22 pm

6Q7GT?

http://www.r-type.org/exhib/aaa0519.htm

Laurdys · 28th Mar 2020, 8:32 pm

I looks like a 6Q7GT

Edit: Double posted

Herald1360 · 28th Mar 2020, 8:37 pm

I rather agree, it does!

Not so mysterious after all.....

Except that odd "2K2" marking. Must be some sort of manufacturer's code but with an unknown manufacturer, not much use.

I'll mark it as such and it can go back into the obscurity of the random valves box.

Sideband · 28th Mar 2020, 10:37 pm

It could be a 12Q7GT same valve with a 12.6V .15A heater. only way to tell is to apply 6V across pins 2 and 7. If the heater doesn't glow, try 12V.....you'll have your answer!

Herald1360 · 28th Mar 2020, 11:42 pm

Quote:

Originally Posted by Sideband

It could be a 12Q7GT same valve with a 12.6V .15A heater. only way to tell is to apply 6V across pins 2 and 7. If the heater doesn't glow, try 12V.....you'll have your answer!

Err...... Been There Done That (With my trusty Thurlby)

Quote:

Originally Posted by Herald1360

.

IO base, pin 6 missing. Looks like maybe a diode-triode with top cap grid. Seems to have the usual 6.3V 0.3A heater on pins 2&7.

Maarten · 1st Apr 2020, 12:55 pm

Is there any evidence of another short line of text above the 2K2 marking? Is that marking darkish and smaller than usual?

28th Mar 2020, 8:16 pm	#1
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Another Mystery Valve Found this one today whilst having a bit of a tidy up in my workshop. IO base, pin 6 missing. Looks like maybe a diode-triode with top cap grid. Seems to have the usual 6.3V 0.3A heater on pins 2&7. Only marking I can read is a faint "2K2 " about half way up the envelope. Can't see if there ever was more. It's not a Klystron! Any bright ideas? Attached Thumbnails __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

28th Mar 2020, 8:22 pm	#2
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,396	Re: Another Mystery Valve 6Q7GT? http://www.r-type.org/exhib/aaa0519.htm

28th Mar 2020, 8:32 pm	#3
Laurdys Pentode Join Date: May 2009 Location: Stockton-on-Tees, County Durham, UK. Posts: 154	Re: Another Mystery Valve I looks like a 6Q7GT Edit: Double posted __________________ If it can be built, it can also be fixed.

28th Mar 2020, 8:37 pm	#4
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Another Mystery Valve I rather agree, it does! Not so mysterious after all..... Except that odd "2K2" marking. Must be some sort of manufacturer's code but with an unknown manufacturer, not much use. I'll mark it as such and it can go back into the obscurity of the random valves box. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

28th Mar 2020, 10:37 pm	#5
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,572	Re: Another Mystery Valve It could be a 12Q7GT same valve with a 12.6V .15A heater. only way to tell is to apply 6V across pins 2 and 7. If the heater doesn't glow, try 12V.....you'll have your answer! __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

1st Apr 2020, 12:55 pm	#7
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,199	Re: Another Mystery Valve Is there any evidence of another short line of text above the 2K2 marking? Is that marking darkish and smaller than usual?