Side and End Contact Valve - UK Vintage Radio Repair and Restoration Discussion Forum

ronbryan · 30th Oct 2007, 12:23 pm

My brother in law found this valve in a box of old lamps (some vacuum type with pips on the top) whilst clearing his parent's home. It appears to be a directly heated triode, with the filament strung between the two end caps via an 'S' shaped tensioning spring. The sealing-off pip is at the side. It has no identifying marks, but looks 1920's to me. Sadly the filament is o/c.

Does anybody know what it is and where it might have been used?

Ron

OldBoffin · 30th Oct 2007, 6:36 pm

Hello Ron,
I think you have a 1918 Flemming Oscillation Valve - this sort of construction was used for Diodes in the Marconi 5Kw Battleship set
according to pictures in my old Handbook for Wireles Telegraphists.
At first it was just a filament surrounded by a cyclinderical "Anode"
used as an alternative to a crystal or magnetic Detector in ship sets.
As you know, Flemming went on to add the Grid to make an Amplifier
and Oscillator.
Its a museum piece!
Regards.
OldBoffin.

Aerodyne · 30th Oct 2007, 8:17 pm

I agree that it looks like a diode, but whether it is fair to call it a 'Fleming diode' depends on your point of view: certainly it isn't one of his original experimental types, I guess whatever its function, it is a commercial production

. BTW, surely the triode valve was an invention credited to Lee DeForest (Audion). He developed a diode-type device similar to Fleming's in 1904 and patented his three-electrode Audion in 1906. Someone on this forum must know something about this thing

-Tony

AC/HL · 31st Oct 2007, 12:09 am

Hi Ron,
I think it's a Marconi V24 HF triode, one of the earliest valves. According to Radio Radio it was developed by H.J.Round in 1916. (page 26)

jim_beacon · 31st Oct 2007, 12:23 am

I'd go with the V24 aswell, they were in production for a great many years, as the navy used a lot in their radios.

Jim.

PJL · 31st Oct 2007, 12:33 am

http://www.g3ngd.talktalk.net/marconi.html has a little bit about it and a picture although the same structure seems to have been used in other valves http://www.mhs.ox.ac.uk/marconi/coll...p?invnum=15771

ronbryan · 31st Oct 2007, 12:14 pm

Thank you Oldboffin, Tony, Bill, Jim and PJL for all your help in identifying the valve.

Whilst looking at the Marconi Collection link supplied by PJL and also the National Valve Museum site, I have noticed that the filament support for the V24 is often a coil spring, as shown in http://www.r-type.org/exhib/aac0049.htm, rather than the large 'S' shaped spring pictured in my example. Because of this difference, I wonder if Forum members think that dull emitter valves type DEV or DEQ are also possibilities.

There is no tungsten evaporated onto the envelope in my example, but presumably this is not conclusive in confirming a dull emitter (DEV or DEQ type), as the valve could have been an unused V24 bright emitter with a broken filament.

On the other hand, the type DEQ illustrated at http://www.r-type.org/exhib/aaj0007.htm has a finer pitched grid than my example and is coated with a green lacquer, so it looks as though a DEV is the more likely choice if it is a dull emitter.

One further thing - it looks as if the idea of removing residual gases with a 'getter' post-dates this type of valve as there is no sign of the getter or its support structure in any of the examples discussed.

Ron

30th Oct 2007, 12:23 pm	#1
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,960	Side and End Contact Valve My brother in law found this valve in a box of old lamps (some vacuum type with pips on the top) whilst clearing his parent's home. It appears to be a directly heated triode, with the filament strung between the two end caps via an 'S' shaped tensioning spring. The sealing-off pip is at the side. It has no identifying marks, but looks 1920's to me. Sadly the filament is o/c. Does anybody know what it is and where it might have been used? Ron Attached Thumbnails

30th Oct 2007, 6:36 pm	#2
OldBoffin Retired Dormant Member Join Date: Jan 2007 Location: Rugeley, Staffordshire, UK. Posts: 54	Re: Side and End Contact Valve Hello Ron, I think you have a 1918 Flemming Oscillation Valve - this sort of construction was used for Diodes in the Marconi 5Kw Battleship set according to pictures in my old Handbook for Wireles Telegraphists. At first it was just a filament surrounded by a cyclinderical "Anode" used as an alternative to a crystal or magnetic Detector in ship sets. As you know, Flemming went on to add the Grid to make an Amplifier and Oscillator. Its a museum piece! Regards. OldBoffin.

30th Oct 2007, 8:17 pm	#3
Aerodyne Octode Join Date: Jun 2004 Location: Hampton Vale, Peterborough, UK. Posts: 1,698	Re: Side and End Contact Valve I agree that it looks like a diode, but whether it is fair to call it a 'Fleming diode' depends on your point of view: certainly it isn't one of his original experimental types, I guess whatever its function, it is a commercial production. BTW, surely the triode valve was an invention credited to Lee DeForest (Audion). He developed a diode-type device similar to Fleming's in 1904 and patented his three-electrode Audion in 1906. Someone on this forum must know something about this thing -Tony

31st Oct 2007, 12:09 am	#4
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,643	Re: Side and End Contact Valve Hi Ron, I think it's a Marconi V24 HF triode, one of the earliest valves. According to Radio Radio it was developed by H.J.Round in 1916. (page 26)

31st Oct 2007, 12:23 am	#5
jim_beacon Retired Dormant Member Join Date: Mar 2003 Location: Bishop's Waltham, Hants, UK. Posts: 939	Re: Side and End Contact Valve I'd go with the V24 aswell, they were in production for a great many years, as the navy used a lot in their radios. Jim.

31st Oct 2007, 12:33 am	#6
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Side and End Contact Valve http://www.g3ngd.talktalk.net/marconi.html has a little bit about it and a picture although the same structure seems to have been used in other valves http://www.mhs.ox.ac.uk/marconi/coll...p?invnum=15771 Last edited by PJL; 31st Oct 2007 at 12:40 am.

31st Oct 2007, 12:14 pm	#7
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,960	Re: Side and End Contact Valve Thank you Oldboffin, Tony, Bill, Jim and PJL for all your help in identifying the valve. Whilst looking at the Marconi Collection link supplied by PJL and also the National Valve Museum site, I have noticed that the filament support for the V24 is often a coil spring, as shown in http://www.r-type.org/exhib/aac0049.htm, rather than the large 'S' shaped spring pictured in my example. Because of this difference, I wonder if Forum members think that dull emitter valves type DEV or DEQ are also possibilities. There is no tungsten evaporated onto the envelope in my example, but presumably this is not conclusive in confirming a dull emitter (DEV or DEQ type), as the valve could have been an unused V24 bright emitter with a broken filament. On the other hand, the type DEQ illustrated at http://www.r-type.org/exhib/aaj0007.htm has a finer pitched grid than my example and is coated with a green lacquer, so it looks as though a DEV is the more likely choice if it is a dull emitter. One further thing - it looks as if the idea of removing residual gases with a 'getter' post-dates this type of valve as there is no sign of the getter or its support structure in any of the examples discussed. Ron