Valve Life - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Nicklyons2 · 4th Mar 2013, 4:31 pm

Quote:

Originally Posted by Sideband

According to Wikepedia:

'The longest recorded valve life was earned by a Mazda AC/P pentode valve (serial No. 4418) in operation at the BBC's main Northern Ireland transmitter at Lisnagarvey. The valve was in service from 1935 until 1961 and had a recorded life of 232,592 hours. The BBC maintained meticulous records of their valves' lives with periodic returns to their central valve stores.
Rich

Hmm, I think I know where Wikipedia got ther info from; the Mazda Valve Data book 1968. And from my copy, a picture of the 'offending' device - and very fine it looks too. I'm thinking that at the time this record was achieved transistors hadn't been around long enough to equal this record. In fact if my maths is vaguely close the very first transistors would have had to survive until 1974 to equal it.

emeritus · 5th Mar 2013, 2:22 am

According to a Mazda Ad in the October 1945 WW, their standard SP-41 valve had been selected for use in submarine repeaters because it had been found to be particularly reliable, still being serviceable after 11,000 hours use. This would no doubt have been continuous use at constant temperature, which would have assisted reliability.

Radio Wrangler · 5th Mar 2013, 8:34 am

There certainly was a fear of valve unreliability. Remember how they were treated separately in warranty clauses? 3 months for the bottles and a year for the rest of the set.

David

HamishBoxer · 5th Mar 2013, 12:24 pm

Over the many years i have done repairs,50 plus years life is nothing for a valve.

Neil Purling · 9th Mar 2013, 3:08 pm

When that Mazda AC/P pentode failed did they actually have a dust-covered spare in the stores?

Nicklyons2 · 9th Mar 2013, 4:06 pm

What I know of the BBC in that era would suggest they would indeed have a spare but it wouldn't be dusty! the main transmitters had proper cleaning ladies and canteen staff, the places were spotless. Remember too that many of the transmitters from the pre-WWII era carried on until the frequency changes in the early 1970s (when R1 left 247m and moved to 275/285m).

5th Mar 2013, 8:34 am	#23
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,248	Re: Valve Life There certainly was a fear of valve unreliability. Remember how they were treated separately in warranty clauses? 3 months for the bottles and a year for the rest of the set. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

5th Mar 2013, 12:24 pm	#24
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,878	Re: Valve Life Over the many years i have done repairs,50 plus years life is nothing for a valve. __________________ G8JET BVWS Archivist and Member V.M.A.R.S

9th Mar 2013, 3:08 pm	#25
Neil Purling Nonode Join Date: Jul 2005 Location: Hull, East Yorkshire, UK. Posts: 2,078	Re: Valve Life When that Mazda AC/P pentode failed did they actually have a dust-covered spare in the stores?

9th Mar 2013, 4:06 pm	#26
Nicklyons2 Octode Join Date: Jan 2013 Location: Barnsley, South Yorkshire, UK. Posts: 1,517	Re: Valve Life What I know of the BBC in that era would suggest they would indeed have a spare but it wouldn't be dusty! the main transmitters had proper cleaning ladies and canteen staff, the places were spotless. Remember too that many of the transmitters from the pre-WWII era carried on until the frequency changes in the early 1970s (when R1 left 247m and moved to 275/285m).