Mystery rectifier - UK Vintage Radio Repair and Restoration Discussion Forum

brymac · 2nd Mar 2020, 6:48 pm

Can anybody shed any light on this unusual looking rectifier valve which has surfaced in a box full of components I obtained from a closed down TV/Radio repair shop? It is marked "Cosmos Red Spot" but I can find no reference to it anywhere and my Mullard High Speed Valve Tester just looked it at and said "You're having a laugh, aren't you?"!!!

Photos attached...

Many thanks,

Bryan

draenog · 2nd Mar 2020, 6:53 pm

It's a very early AC valve - part of a range released by Cosmos in 1927. The base predates the B5 base. More details here, including pictures of the rare adaptor:

http://www.r-type.org/exhib/aaj0176.htm

draenog · 2nd Mar 2020, 6:56 pm

Cosmos AC/R "Red Spot" here:

http://www.r-type.org/exhib/aby0081.htm

brymac · 2nd Mar 2020, 7:01 pm

That's really helpful - thanks! I had no idea it was that old! I'll see if anybody wants it...

Bryan

draenog · 2nd Mar 2020, 7:07 pm

I have a couple, with adaptors. They were later branded as Mazda. I would be interested in it...

Radio Wrangler · 3rd Mar 2020, 12:16 am

You can just make out the old Metropolitan Vickers logo in the circle amidst the pins, moulded into the bakelite.

David

trobbins · 6th Mar 2020, 11:14 pm

The green spot photos show a 'spring' loop holder for the top of the heater filament, whereas the red-spot photos show a top holder bar without a 'loop'.

Was the 'glass bead' technique in common use during that period as a top end insulated support mechanism ?

2nd Mar 2020, 6:48 pm	#1
brymac Hexode Join Date: Nov 2004 Location: East Sussex, UK. Posts: 389	Mystery rectifier Can anybody shed any light on this unusual looking rectifier valve which has surfaced in a box full of components I obtained from a closed down TV/Radio repair shop? It is marked "Cosmos Red Spot" but I can find no reference to it anywhere and my Mullard High Speed Valve Tester just looked it at and said "You're having a laugh, aren't you?"!!! Photos attached... Many thanks, Bryan Attached Thumbnails

2nd Mar 2020, 6:53 pm	#2
draenog Tetrode Join Date: Oct 2009 Location: Chepstow, Monmouthshire, UK. Posts: 60	Re: Mystery rectifier It's a very early AC valve - part of a range released by Cosmos in 1927. The base predates the B5 base. More details here, including pictures of the rare adaptor: http://www.r-type.org/exhib/aaj0176.htm

2nd Mar 2020, 6:56 pm	#3
draenog Tetrode Join Date: Oct 2009 Location: Chepstow, Monmouthshire, UK. Posts: 60	Re: Mystery rectifier Cosmos AC/R "Red Spot" here: http://www.r-type.org/exhib/aby0081.htm

2nd Mar 2020, 7:01 pm	#4
brymac Hexode Join Date: Nov 2004 Location: East Sussex, UK. Posts: 389	Re: Mystery rectifier That's really helpful - thanks! I had no idea it was that old! I'll see if anybody wants it... Bryan

2nd Mar 2020, 7:07 pm	#5
draenog Tetrode Join Date: Oct 2009 Location: Chepstow, Monmouthshire, UK. Posts: 60	Re: Mystery rectifier I have a couple, with adaptors. They were later branded as Mazda. I would be interested in it...

3rd Mar 2020, 12:16 am	#6
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: Mystery rectifier You can just make out the old Metropolitan Vickers logo in the circle amidst the pins, moulded into the bakelite. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

6th Mar 2020, 11:14 pm	#7
trobbins Heptode Join Date: Oct 2009 Location: Melbourne Australia Posts: 901	Re: Mystery rectifier The green spot photos show a 'spring' loop holder for the top of the heater filament, whereas the red-spot photos show a top holder bar without a 'loop'. Was the 'glass bead' technique in common use during that period as a top end insulated support mechanism ?