Mystery Valve - UK Vintage Radio Repair and Restoration Discussion Forum

David Simpson · 10th Sep 2017, 2:37 pm

Folks, does anyone know what valve this is, please ?
Have checked "Valve Museum" site, but no joy. Perhaps a "Barkhausen" VHF design ?

Regards, David

turretslug · 10th Sep 2017, 4:54 pm

Wild bit of straw-clutching- a low-power split anode magnetron diode, with a narrowed tubular bulb intended to fit closely in the pole-pieces of a powerful magnet and flying output leads to a balanced VHF/UHF load? The base looks something like a British B7? or similar early/mid 'thirties when a lot of this sort of thing was being investigated.

David Simpson · 10th Sep 2017, 5:39 pm

Yep, definitely a B7 Base. Right enough, that narrow neck lends itself to magnetic poles fitment.
Just noticed - written inside, in white on the pinch is :- DTAS 260C, but nothing at all written on the glass envelope. No sign of a coiled grid structure.

Regards, David

VT FUSE · 10th Sep 2017, 7:37 pm

think turretslug is closer to winning the coconut than clutching at straws! The French did a lot of pre-war work along with others on the split anode magnetron.
I have seen a few types like the one depicted but most people think of the Harry Boot/John Randall cavity magnetron which was produced by G.E.C whenever the device is mentioned.
The lack of grid stricture confirms this,I did wonder if it was a gammatron briefly but the parallel section of bulb envelope suggests magnet pole placement.

10th Sep 2017, 2:37 pm	#1
David Simpson Nonode Join Date: Mar 2008 Location: Aberdeen, UK. Posts: 2,858	Mystery Valve Folks, does anyone know what valve this is, please ? Have checked "Valve Museum" site, but no joy. Perhaps a "Barkhausen" VHF design ? Regards, David Attached Thumbnails

10th Sep 2017, 4:54 pm	#2
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,400	Re: Mystery Valve Wild bit of straw-clutching- a low-power split anode magnetron diode, with a narrowed tubular bulb intended to fit closely in the pole-pieces of a powerful magnet and flying output leads to a balanced VHF/UHF load? The base looks something like a British B7? or similar early/mid 'thirties when a lot of this sort of thing was being investigated.

10th Sep 2017, 5:39 pm	#3
David Simpson Nonode Join Date: Mar 2008 Location: Aberdeen, UK. Posts: 2,858	Re: Mystery Valve Yep, definitely a B7 Base. Right enough, that narrow neck lends itself to magnetic poles fitment. Just noticed - written inside, in white on the pinch is :- DTAS 260C, but nothing at all written on the glass envelope. No sign of a coiled grid structure. Regards, David Last edited by David Simpson; 10th Sep 2017 at 5:41 pm. Reason: Added info

10th Sep 2017, 7:37 pm	#4
VT FUSE Hexode Join Date: Aug 2010 Location: Malvern, Worcestershire, UK. Posts: 347	Re: Mystery Valve think turretslug is closer to winning the coconut than clutching at straws! The French did a lot of pre-war work along with others on the split anode magnetron. I have seen a few types like the one depicted but most people think of the Harry Boot/John Randall cavity magnetron which was produced by G.E.C whenever the device is mentioned. The lack of grid stricture confirms this,I did wonder if it was a gammatron briefly but the parallel section of bulb envelope suggests magnet pole placement.