"Secondary Emission" valves. - UK Vintage Radio Repair and Restoration Discussion Forum

G6Tanuki · 18th May 2017, 9:11 pm

I've always had an interest in the secondary-emission approach as a way to get extra gain in a valve - and it seems that various manufacturers tried it but largely failed to get it to work as a practical prospect.

http://www.r-type.org/exhib/aai0191.htm

http://www.r-type.org/exhib/aaj0017.htm

http://www.r-type.org/articles/art-023.htm

The only place I can think of where "secondary emission" was a success was in photomultiplier tubes and some TV camera tubes.

OK, some use of something akin to the "secondary emission" effect was also used as a way to nullify the space-charge in "12V-HT" car-radio valves in the 1950s but that always seemed to me to be rather different.

Can anyone think of other examples of secondary-emission being used in real-world situations?

stevehertz · 19th May 2017, 2:49 pm

I had a pre-war TV that used the TSE4 valve although I can't remember which one it was now. I also had a spare or two of brand new, boxed valves. They were/are as rare as rocking horse droppings and Tudor Rees used to advertise them at mortgage level prices. So that's another application, TV receiving sets/equipment.

M0FYA Andy · 19th May 2017, 3:34 pm

There's the 'giant acorn', type 1630.

It didn't have a long life, only about 50 hours before losing emission. So not very successful...........

It looks nice, though, I have a couple of examples in my collection.

Andy

G6Tanuki · 20th May 2017, 11:40 am

That's just so wonderfully crazy!

Maarten · 22nd May 2017, 3:43 am

I think Philips used a secondary emission valve as a phase changer in one or two PA amplifiers, just before or just after WWII.

18th May 2017, 9:11 pm	#1
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,996	"Secondary Emission" valves. I've always had an interest in the secondary-emission approach as a way to get extra gain in a valve - and it seems that various manufacturers tried it but largely failed to get it to work as a practical prospect. http://www.r-type.org/exhib/aai0191.htm http://www.r-type.org/exhib/aaj0017.htm http://www.r-type.org/articles/art-023.htm The only place I can think of where "secondary emission" was a success was in photomultiplier tubes and some TV camera tubes. OK, some use of something akin to the "secondary emission" effect was also used as a way to nullify the space-charge in "12V-HT" car-radio valves in the 1950s but that always seemed to me to be rather different. Can anyone think of other examples of secondary-emission being used in real-world situations?

19th May 2017, 2:49 pm	#2
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,830	Re: "Secondary Emission" valves. I had a pre-war TV that used the TSE4 valve although I can't remember which one it was now. I also had a spare or two of brand new, boxed valves. They were/are as rare as rocking horse droppings and Tudor Rees used to advertise them at mortgage level prices. So that's another application, TV receiving sets/equipment. __________________ A digital radio is the latest thing, but a vintage wireless is forever..

20th May 2017, 11:40 am	#4
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,996	Re: "Secondary Emission" valves. That's just so wonderfully crazy!

22nd May 2017, 3:43 am	#5
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,199	Re: "Secondary Emission" valves. I think Philips used a secondary emission valve as a phase changer in one or two PA amplifiers, just before or just after WWII.