Metal-cased valves. - UK Vintage Radio Repair and Restoration Discussion Forum

stephanie · 28th Aug 2006, 7:36 pm

I don't know if British/Euro sets used these....some Western radios do.

I've never taken one apart, but are these essentially glass valves that are permanently mounted in an earthed metal shield or is the metal case actually what contains the vacuum?

Ed_Dinning · 28th Aug 2006, 7:42 pm

Hi Stephanie, These were quite popular in the UK in many Kit sets as well as minatures. The Metal can covers a conventional glass "vacuum holder". It acts as its own screen. These metal versions were also smaller than the GT types of the same tube. I have a few of them and reserve them for my communication sets.
There was also the famous EF50 series of valves, on a B9G base that were used extensively in WW2 in radar etc. These are of a similar metal can construction.
There were also the "catkin" valves that I believe had a metal can that was the anode, but there may have bgeen glass used in other areas. Keith Throwers book on Valves will have all the details.

HTH Ed

Roy · 28th Aug 2006, 7:52 pm

Interesting article on metal valve construction:

http://www.r-type.org/static/6j5.htm

Roy

stephanie · 28th Aug 2006, 8:17 pm

Well, that's a relief to hear. That means I don't have to be so concerned about a little surface rust on a metal-clad valve.

JHGibson · 29th Aug 2006, 2:49 am

There are two styles of metal tubes. There is the all glass regular tube inside a metal can, the EF50 is a good example of this. The other far more common metal tube such as the 6SK7, 6C5 (no suffix here) etc have the metal envelope holding the vacuum, with the leads coming out of glass seals in the base, then to octal pins.
John.

KEITHW · 30th Aug 2006, 4:47 pm

I thought this might be of interest. Its an article from the 'Popular Wireless' magazine of July 8th 1933. I like the bit about a catkin valve being sent all the way to Aberdeen and back with only a label to protect it. If they weren't so rare I'd like to re-enact this to see how it would cope with the modern Royal Mail!

Pictured are two catkins I have. Left is a VMP4 and right a MH4. They are about 4'' high.

To view the article you need to save it to 'My pictures' or similar and then open it with preview (I couldn't work out how to save it under 200 kb and still have it readable).

Keith

joe · 31st Aug 2006, 11:02 am

Hi Stephanie,

A little bit of their history that I read somewhere or other.
In the early days of transmitters the limits of technology with glass valves had just about been reached due to the heat of 1Kw+ bottles. Marconi-Osram having developed improved seals between glass & metal built a transmitting valve with a metal body & glass at each end, the whole thing contained a vacuum & the metal part was the anode to which cooling fins could be welded ( & later on water pipes ) These were known as Cooled Anode Transmitters, or CAT valves.

The next development, as KEITHW's article says was to make little baby ones called Catkins for receiving use. They were used in the mid 30s mainly in Marconi- HMV sets.

BTW the anode was definitely live at HT voltage as I can testify from the number of times I got a belt from trying to change the station on an old car radio minus its cover whilst driving

Joe

stephanie · 31st Aug 2006, 3:01 pm

The catkins sure look flashier than our metal valves - which are essentially a black metal tube crimped onto an octal base plug.

Jeremy M0RVB · 1st Sep 2006, 4:18 pm

Quote:

Originally Posted by joe

Marconi-Osram having developed improved seals between glass & metal built a transmitting valve with a metal body & glass at each end, the whole thing contained a vacuum & the metal part was the anode to which cooling fins could be welded ( & later on water pipes ) These were known as Cooled Anode Transmitters, or CAT valves.

There were a range of these beasties, the ACT's are air cooled and the CATs (and CARs and CAMs) water cooled (see this monster http://www.tubecollector.org/rd150yb.htm). In some cases the only difference between ACT and CAT was the lack of fins and addition of a water jacket, but you can't cool a 150Kw+ CW valve by air so there are no mega-big ACTs.

There were valves made of glass that could stand higher powers than normal - the silica valves. They were a bit specialised though.

jan_tomek · 22nd Sep 2006, 3:24 pm

Quote:

Originally Posted by stephanie

The catkins sure look flashier than our metal valves - which are essentially a black metal tube crimped onto an octal base plug.

Good morning Stephanie,

you may find nice example of German "11" series tubes at

http://www.radiomuseum.org/tubes/tube_ef11.html

Regards

Jan

FrankB · 4th Oct 2006, 9:46 pm

Stephanie,
You can usually use the metal types to replace a glass type, but be sure to check the "shield" pin of the metal tube under the socket.
Sometimes they used the pin (unused in many glass types) on the socket as a tie point, and grounding it may let the "smoke" escape from the parts attached to the socket pin.

28th Aug 2006, 7:36 pm	#1
stephanie Retired Dormant Member Join Date: Jul 2005 Location: New Bern, North Carolina, USA Posts: 346	Metal-cased valves. I don't know if British/Euro sets used these....some Western radios do. I've never taken one apart, but are these essentially glass valves that are permanently mounted in an earthed metal shield or is the metal case actually what contains the vacuum?

28th Aug 2006, 7:42 pm	#2
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: Metal valves Hi Stephanie, These were quite popular in the UK in many Kit sets as well as minatures. The Metal can covers a conventional glass "vacuum holder". It acts as its own screen. These metal versions were also smaller than the GT types of the same tube. I have a few of them and reserve them for my communication sets. There was also the famous EF50 series of valves, on a B9G base that were used extensively in WW2 in radar etc. These are of a similar metal can construction. There were also the "catkin" valves that I believe had a metal can that was the anode, but there may have bgeen glass used in other areas. Keith Throwers book on Valves will have all the details. HTH Ed

28th Aug 2006, 7:52 pm	#3
Roy Hexode Join Date: May 2003 Location: Hertfordshire, UK Posts: 258	Re: Metal valves Interesting article on metal valve construction: http://www.r-type.org/static/6j5.htm Roy

28th Aug 2006, 8:17 pm	#4
stephanie Retired Dormant Member Join Date: Jul 2005 Location: New Bern, North Carolina, USA Posts: 346	Re: Metal valves Well, that's a relief to hear. That means I don't have to be so concerned about a little surface rust on a metal-clad valve.

29th Aug 2006, 2:49 am	#5
JHGibson Retired Dormant Member Join Date: Apr 2003 Location: Salt Spring Island, BC, Canada Posts: 368	Re: Metal valves There are two styles of metal tubes. There is the all glass regular tube inside a metal can, the EF50 is a good example of this. The other far more common metal tube such as the 6SK7, 6C5 (no suffix here) etc have the metal envelope holding the vacuum, with the leads coming out of glass seals in the base, then to octal pins. John.

30th Aug 2006, 4:47 pm	#6
KEITHW Retired Dormant Member Join Date: Nov 2005 Location: Pocklington, East Yorkshire, UK. Posts: 171	Re: Metal valves I thought this might be of interest. Its an article from the 'Popular Wireless' magazine of July 8th 1933. I like the bit about a catkin valve being sent all the way to Aberdeen and back with only a label to protect it. If they weren't so rare I'd like to re-enact this to see how it would cope with the modern Royal Mail! Pictured are two catkins I have. Left is a VMP4 and right a MH4. They are about 4'' high. To view the article you need to save it to 'My pictures' or similar and then open it with preview (I couldn't work out how to save it under 200 kb and still have it readable). Keith Attached Thumbnails

31st Aug 2006, 11:02 am	#7
joe Rest in Peace Join Date: Apr 2003 Location: Edgware, North London. Posts: 307	Re: Metal valves Hi Stephanie, A little bit of their history that I read somewhere or other. In the early days of transmitters the limits of technology with glass valves had just about been reached due to the heat of 1Kw+ bottles. Marconi-Osram having developed improved seals between glass & metal built a transmitting valve with a metal body & glass at each end, the whole thing contained a vacuum & the metal part was the anode to which cooling fins could be welded ( & later on water pipes ) These were known as Cooled Anode Transmitters, or CAT valves. The next development, as KEITHW's article says was to make little baby ones called Catkins for receiving use. They were used in the mid 30s mainly in Marconi- HMV sets. BTW the anode was definitely live at HT voltage as I can testify from the number of times I got a belt from trying to change the station on an old car radio minus its cover whilst driving Joe

31st Aug 2006, 3:01 pm	#8
stephanie Retired Dormant Member Join Date: Jul 2005 Location: New Bern, North Carolina, USA Posts: 346	Re: Metal valves The catkins sure look flashier than our metal valves - which are essentially a black metal tube crimped onto an octal base plug.

4th Oct 2006, 9:46 pm	#11
FrankB Heptode Join Date: Oct 2005 Location: Olympia, Washington, USA. Posts: 664	Re: Metal valves Stephanie, You can usually use the metal types to replace a glass type, but be sure to check the "shield" pin of the metal tube under the socket. Sometimes they used the pin (unused in many glass types) on the socket as a tie point, and grounding it may let the "smoke" escape from the parts attached to the socket pin.