What is it? - UK Vintage Radio Repair and Restoration Discussion Forum

govjohn · 1st Jul 2015, 9:16 pm

Near where I live there is an exhibition of operational vintage radio rooms as Part of the 'Internal Fire' museum which is devoted to early stationary (as opposed to traction) engines. Attached to the radio section is a display of early valves all of them seem to be correctly identified except for the one in the thumbnails.
The main museum has something which may be of some interest to some members of this Forum this is a 3MW alternator powered by a Proteus Gas Turbine these gen sets were used by the CEGB to meet Peak demand in remote areas. This is thought to be the only one run for public display and it is VERY impressive to see and hear.
Back to the subject of this post, The valve is made of a rough looking glass and with only four connections is probably a directly heated triode but what is is from, does anyone have any ideas? Sorry about the quality of the Photo's but the museum is staffed by volunteers and there was no one around to open the cabinet so I could get a better shot.
John

Phil G4SPZ · 1st Jul 2015, 9:40 pm

Hi John, and I agree that Internal Fire is an excellent museum - I've visited many times.

I suggest that the valve you photographed may be a mercury arc or mercury vapour rectifier. Have you tried a search on the excellent National Valve Museum at www.r-type.org? Alternatively, drop the museum an e-mail, I'm sure they will know.

Cobaltblue · 1st Jul 2015, 9:57 pm

It looks like a Silica transmitting valve

See this one here: http://www.r-type.org/addtext/add024.htm

Cheers

Mike T

Cobaltblue · 2nd Jul 2015, 5:19 am

Further to my previous post the exhibit seems to be very similar to this example.

http://www.r-type.org/exhib/aaa0633.htm

Cheers

Mike T

govjohn · 2nd Jul 2015, 8:18 am

That's it! Thanks a lot.
John.

Tractorfan · 2nd Jul 2015, 12:40 pm

Hi,
The power station I worked at had two sets of two Rolls Royce Avon gas turbine engines driving the emergency standby plant. (OT bit).
Odd how silica glass transmitting valves always look rough. Obviously it wasn't possible to make them smooth and clear. Maybe that was the only way at the time, and I wonder if advances in silica glass technology have made it easier?
Cheers, Pete.

Hunts smoothing bomb · 2nd Jul 2015, 12:44 pm

Impressive, the heater/filament alone consumes over 1kw!

Cheers

broadgage · 2nd Jul 2015, 12:59 pm

Yes but I presume that the 1KW is either DC or single phase AC.
Very large transmitter valves were manufactured with 3 phase heaters ! this saved the expense of providing a DC filament supply and introduced no hum unlike single phase AC did.

russell_w_b · 2nd Jul 2015, 1:12 pm

Quote:

Originally Posted by broadgage

Yes but I presume that the 1KW is either DC or single phase AC.
Very large transmitter valves were manufactured with 3 phase heaters...

Our 125kW HF (and audio) BY1144s were two-phase connected via a Scott Transformer to cancel hum.

2nd Jul 2015, 2:00 pm

Two things...

The lead outs are sealed using lead (the metal) in early ones like this one (hence the length) afterwards they used a chain of different glasses to eventually match the expansion rate of the lead in wires.

Silica (quartz) is awfully difficult to work because of the high melting point, 1713C, and no real soft point, either liquid or solid, still they did it!

G6Tanuki · 2nd Jul 2015, 2:31 pm

The quartz-glass envelopes of these valves could be (and was) opened for the internal electrode-assembly to be repaired!

First, the vacuum was let-out; then the quartz annealed in the area where the cut was to be made. Then a diamond-tipped tool was used to cut round the diameter of the envelope in the annealed area. The two halves could then be pulled apart to access the electrodes/heater inside for repair.

Re-joining the two halves was done using an Oxy-Hydrogen flame and a very steady hand. Then, the whole thing was heated in a special oven to drive off any adsorbed gases from the electrode assembly, it was pumped-down, and resealed.

Given the cost and specialist nature of these valves, repairing them when they failed obviously made sense. You wouldn't do that with a 12AT7.

PaulM · 2nd Jul 2015, 2:40 pm

At the risk of being a little OT . . .

Re the link to 'Silica Valves' ( http://www.r-type.org/addtext/add024.htm ). This refers to MOV silica types being made especially for CH use. Is that right, or was it one of the later incarnations of CH? I believe that the CH transmitters were made by Metropolitan Vickers (Metrovick) of Manchester and used their continually evacuated valves ('demountable'). The same technology had been used in their 240 line 17 KW VHF TV transmitter built for Baird Television Ltd. for the Alexandra Palace TV trials in 1936. BTW, by then the company had virtually nothing to do with John Logie other than his name.

The Metrovick story is in this link here:

http://www.gracesguide.co.uk/Metropo...low:_1929-1939 See the paragraph headed 'Radio Valves'.

Also here (half way down):

http://www.bairdtelevision.com/crystalpalace.html

And here (under 'Transmitter Details':

https://en.wikipedia.org/wiki/Chain_Home

Finally here:

http://www.niman.org.uk/chainhome/fi...ment_v4b-e.pdf

Now, it could be correct that MOV types were used in some WWII CH work, but the Metrovick Type 43 was really the star device as I understand the story.

Has anyone else any other details?

Best regards,

Paul M

PaulM · 2nd Jul 2015, 3:32 pm

After some digging, I might have an answer to my own question.

According to L Brown in his book Technical and Military Imperatives: A Radar History of World War 2, pages 53-54, very early CH TX used a silica type valve known as Type NT46 which was soon replaced by the Metrovick type.

It looks like the National Valve Museum is probably correct about MOV silica types as applied to early CH work but they don't say that it wasn't really up to the job and replaced by the Metrovick technology.

Best regards,

Paul M

2nd Jul 2015, 4:54 pm

This http://www.amazon.co.uk/Saga-Marconi.../dp/095391271X is where I got my information, well worth getting.

ColinTheAmpMan1 · 2nd Jul 2015, 8:10 pm

I, too, have this book. It is available from Vyse Amps at £25 hardback or £9.90 softback, plus £4.50 UK postage:

http://vyseamps.com/books.htm

I would rather the authors/publisher got the financial benefit than Amazon. While being pretty informative about a lot of stuff relating to M-O Valve, it must be said that it is bristling with errors. I have a list of these which I must type out sometime. The authors worked at M-O, with Barry Vyse becoming the MD.

Colin.

boxdoctor · 3rd Jul 2015, 8:49 am

Anybody who has access to The Admiralty Handbook of Wireless Telegraphy (Vol 2) published about 1930 will find some pictures, (well at least one as I remember), and column space devoted to these valve types.
I once had this book as a youngster, but unwisely swapped it for a 'rather nice' mains transformer.
Damn!! Tony.

1st Jul 2015, 9:16 pm	#1
govjohn Pentode Join Date: May 2011 Location: Cardigan, Ceredigion, UK. Posts: 100	What is it? Near where I live there is an exhibition of operational vintage radio rooms as Part of the 'Internal Fire' museum which is devoted to early stationary (as opposed to traction) engines. Attached to the radio section is a display of early valves all of them seem to be correctly identified except for the one in the thumbnails. The main museum has something which may be of some interest to some members of this Forum this is a 3MW alternator powered by a Proteus Gas Turbine these gen sets were used by the CEGB to meet Peak demand in remote areas. This is thought to be the only one run for public display and it is VERY impressive to see and hear. Back to the subject of this post, The valve is made of a rough looking glass and with only four connections is probably a directly heated triode but what is is from, does anyone have any ideas? Sorry about the quality of the Photo's but the museum is staffed by volunteers and there was no one around to open the cabinet so I could get a better shot. John Attached Thumbnails

1st Jul 2015, 9:40 pm	#2
Phil G4SPZ Dekatron Join Date: Apr 2005 Location: Bewdley, Worcestershire, UK. Posts: 4,748	Re: What is it? Hi John, and I agree that Internal Fire is an excellent museum - I've visited many times. I suggest that the valve you photographed may be a mercury arc or mercury vapour rectifier. Have you tried a search on the excellent National Valve Museum at www.r-type.org? Alternatively, drop the museum an e-mail, I'm sure they will know. __________________ Phil Optimist [n]: One who is not in possession of the full facts Last edited by Phil G4SPZ; 1st Jul 2015 at 9:44 pm. Reason: Afterthought

1st Jul 2015, 9:57 pm	#3
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,866	Re: What is it? It looks like a Silica transmitting valve See this one here: http://www.r-type.org/addtext/add024.htm Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

2nd Jul 2015, 5:19 am	#4
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,866	Re: What is it? Further to my previous post the exhibit seems to be very similar to this example. http://www.r-type.org/exhib/aaa0633.htm Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

2nd Jul 2015, 8:18 am	#5
govjohn Pentode Join Date: May 2011 Location: Cardigan, Ceredigion, UK. Posts: 100	Re: What is it? That's it! Thanks a lot. John.

2nd Jul 2015, 12:40 pm	#6
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,183	Re: What is it? Hi, The power station I worked at had two sets of two Rolls Royce Avon gas turbine engines driving the emergency standby plant. (OT bit). Odd how silica glass transmitting valves always look rough. Obviously it wasn't possible to make them smooth and clear. Maybe that was the only way at the time, and I wonder if advances in silica glass technology have made it easier? Cheers, Pete. __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

2nd Jul 2015, 12:44 pm	#7
Hunts smoothing bomb Octode Join Date: Oct 2005 Location: Wimborne, Dorset, UK. Posts: 1,407	Re: What is it? Impressive, the heater/filament alone consumes over 1kw! Cheers __________________ Lee

2nd Jul 2015, 12:59 pm	#8
broadgage Nonode Join Date: Jan 2010 Location: North Somerset, UK. Posts: 2,129	Re: What is it? Yes but I presume that the 1KW is either DC or single phase AC. Very large transmitter valves were manufactured with 3 phase heaters ! this saved the expense of providing a DC filament supply and introduced no hum unlike single phase AC did.

2nd Jul 2015, 2:00 pm	#10
Guest Guest Posts: n/a	Re: What is it? Two things... The lead outs are sealed using lead (the metal) in early ones like this one (hence the length) afterwards they used a chain of different glasses to eventually match the expansion rate of the lead in wires. Silica (quartz) is awfully difficult to work because of the high melting point, 1713C, and no real soft point, either liquid or solid, still they did it! Last edited by Guest; 2nd Jul 2015 at 2:01 pm. Reason: To make more sense!

2nd Jul 2015, 2:31 pm	#11
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: What is it? The quartz-glass envelopes of these valves could be (and was) opened for the internal electrode-assembly to be repaired! First, the vacuum was let-out; then the quartz annealed in the area where the cut was to be made. Then a diamond-tipped tool was used to cut round the diameter of the envelope in the annealed area. The two halves could then be pulled apart to access the electrodes/heater inside for repair. Re-joining the two halves was done using an Oxy-Hydrogen flame and a very steady hand. Then, the whole thing was heated in a special oven to drive off any adsorbed gases from the electrode assembly, it was pumped-down, and resealed. Given the cost and specialist nature of these valves, repairing them when they failed obviously made sense. You wouldn't do that with a 12AT7.

2nd Jul 2015, 2:40 pm	#12
PaulM Hexode Join Date: Nov 2006 Location: Near Lincoln, UK. Posts: 483	Re: What is it? At the risk of being a little OT . . . Re the link to 'Silica Valves' ( http://www.r-type.org/addtext/add024.htm ). This refers to MOV silica types being made especially for CH use. Is that right, or was it one of the later incarnations of CH? I believe that the CH transmitters were made by Metropolitan Vickers (Metrovick) of Manchester and used their continually evacuated valves ('demountable'). The same technology had been used in their 240 line 17 KW VHF TV transmitter built for Baird Television Ltd. for the Alexandra Palace TV trials in 1936. BTW, by then the company had virtually nothing to do with John Logie other than his name. The Metrovick story is in this link here: http://www.gracesguide.co.uk/Metropo...low:_1929-1939 See the paragraph headed 'Radio Valves'. Also here (half way down): http://www.bairdtelevision.com/crystalpalace.html And here (under 'Transmitter Details': https://en.wikipedia.org/wiki/Chain_Home Finally here: http://www.niman.org.uk/chainhome/fi...ment_v4b-e.pdf Now, it could be correct that MOV types were used in some WWII CH work, but the Metrovick Type 43 was really the star device as I understand the story. Has anyone else any other details? Best regards, Paul M

2nd Jul 2015, 3:32 pm	#13
PaulM Hexode Join Date: Nov 2006 Location: Near Lincoln, UK. Posts: 483	Re: What is it? After some digging, I might have an answer to my own question. According to L Brown in his book Technical and Military Imperatives: A Radar History of World War 2, pages 53-54, very early CH TX used a silica type valve known as Type NT46 which was soon replaced by the Metrovick type. It looks like the National Valve Museum is probably correct about MOV silica types as applied to early CH work but they don't say that it wasn't really up to the job and replaced by the Metrovick technology. Best regards, Paul M

2nd Jul 2015, 4:54 pm	#14
Guest Guest Posts: n/a	Re: What is it? This http://www.amazon.co.uk/Saga-Marconi.../dp/095391271X is where I got my information, well worth getting.

2nd Jul 2015, 8:10 pm	#15
ColinTheAmpMan1 Octode Join Date: Jan 2012 Location: Wimbledon, London, UK. Posts: 1,465	Re: What is it? I, too, have this book. It is available from Vyse Amps at £25 hardback or £9.90 softback, plus £4.50 UK postage: http://vyseamps.com/books.htm I would rather the authors/publisher got the financial benefit than Amazon. While being pretty informative about a lot of stuff relating to M-O Valve, it must be said that it is bristling with errors. I have a list of these which I must type out sometime. The authors worked at M-O, with Barry Vyse becoming the MD. Colin.

3rd Jul 2015, 8:49 am	#16
boxdoctor Rest in Peace Join Date: Sep 2010 Location: Ripley, Derbyshire, UK. Posts: 785	Re: What is it? Anybody who has access to The Admiralty Handbook of Wireless Telegraphy (Vol 2) published about 1930 will find some pictures, (well at least one as I remember), and column space devoted to these valve types. I once had this book as a youngster, but unwisely swapped it for a 'rather nice' mains transformer. Damn!! Tony.