Please help identify this B7G valve. - UK Vintage Radio Repair and Restoration Discussion Forum

G4XWDJim · 23rd Sep 2014, 8:56 pm

It's 6.3 volts and the heater resistance is 5.1 ohms. Anode is at pin 5 and screen looks to be pin 7.

It's 52mm tall from bottom of pins to top of pip.

I've compared it with lots of valves I have but nothing is similar.

It looks like it has the remains of the military crowsfoot and the figure that does show could be a 6 or a G.

TIA,

Jim

turretslug · 23rd Sep 2014, 9:07 pm

EL91/6AM5/CV136? A running heater current of 0.2A would be a pointer. Grid radiators suggest a hot-running PA intention.

FERNSEH · 23rd Sep 2014, 9:09 pm

Looks like a small power output pentode. The EL91/6AM5 perhaps?

Also similar the CV4043, 6516 and M8082.

http://www.radiomuseum.org/tubes/tube_6am5.html

DFWB.

G4XWDJim · 23rd Sep 2014, 9:57 pm

Thanks. My first thought was that it was an EL91 but comparing the two together the electrode structure of the unknown one is slightly smaller. I never know what degree of difference two valves made by different manufacturers can have and still have the same number.

I think I'll stick it in the valve tester and see what results it gives.

Jim

Sideband · 23rd Sep 2014, 10:01 pm

I'd go for EL91 as well. Data also here

Skywave · 26th Sep 2014, 2:04 pm

EL95?

Al.

Jeremy M0RVB · 26th Sep 2014, 2:46 pm

CV136 fits - http://www.tubecollector.org/cv136.htm - it has the arrow so ought to be a CV, and it looks like a '6' in the photo.

23rd Sep 2014, 8:56 pm	#1
G4XWDJim Octode Join Date: Oct 2008 Location: Littlehampton, West Sussex, UK. Posts: 1,465	Please help identify this B7G valve. It's 6.3 volts and the heater resistance is 5.1 ohms. Anode is at pin 5 and screen looks to be pin 7. It's 52mm tall from bottom of pins to top of pip. I've compared it with lots of valves I have but nothing is similar. It looks like it has the remains of the military crowsfoot and the figure that does show could be a 6 or a G. TIA, Jim Attached Thumbnails

23rd Sep 2014, 9:07 pm	#2
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,400	Re: Please help identify this B7G valve. EL91/6AM5/CV136? A running heater current of 0.2A would be a pointer. Grid radiators suggest a hot-running PA intention.

23rd Sep 2014, 9:09 pm	#3
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Please help identify this B7G valve. Looks like a small power output pentode. The EL91/6AM5 perhaps? Also similar the CV4043, 6516 and M8082. http://www.radiomuseum.org/tubes/tube_6am5.html DFWB.

23rd Sep 2014, 9:57 pm	#4
G4XWDJim Octode Join Date: Oct 2008 Location: Littlehampton, West Sussex, UK. Posts: 1,465	Re: Please help identify this B7G valve. Thanks. My first thought was that it was an EL91 but comparing the two together the electrode structure of the unknown one is slightly smaller. I never know what degree of difference two valves made by different manufacturers can have and still have the same number. I think I'll stick it in the valve tester and see what results it gives. Jim

23rd Sep 2014, 10:01 pm	#5
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,580	Re: Please help identify this B7G valve. I'd go for EL91 as well. Data also here __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

26th Sep 2014, 2:04 pm	#6
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: Please help identify this B7G valve. EL95? Al.

26th Sep 2014, 2:46 pm	#7
Jeremy M0RVB Hexode Join Date: Jul 2003 Location: Leeds, West Yorkshire, UK. Posts: 458	Re: Please help identify this B7G valve. CV136 fits - http://www.tubecollector.org/cv136.htm - it has the arrow so ought to be a CV, and it looks like a '6' in the photo.