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In Reply to: Forgetabout tube ratings. posted by Allen Wright on October 8, 2010 at 03:33:48:
Allen,
Having many military tube euipment manuals and having scrapped military tube equipment you first have to realize that unless under combat situation tubes were considered an infinite resource and the cost of recalibrating a radar set under combat conditions was far, far greater than the cost of a set of tubes so, yeah, let 'em burn. But the military also published books of "preferred circuits" - I have several from the Navy from the 1960s - that were "preferred" for, among other things, running tubes extremely conservatively far below consumer applications. Also in many pieces of mil spec gear under the cover would be a complete spare set of tubes already broken but really never used (I've never figured out to best describe these as NOS or UOS - but since I've not had the boxes I've settled for UOS prices usually).
So there'a a basic philosophical difference here: first that you don't want to be "caught with your pants down" (we actually detected the planes approaching Pearl Harbor but being unfamiliar with the crude part time radar we ignored them)and; secondly - like much of the military "price is no object."
And none of this addresses the "sleeping sickness" problem identified in the late 1940s-1950s when tube computers came around. Since their power supplies were regulated and very steady - as is our current power line voltages (in general) cut off tubes went dead (preWWII daily 100-115 line voltage swings were common especially in urban areas with much use and rural areas with miles of swaying power lines).
What might help is if you can get a souce of the literature of the day such as back issues of "Radio and Television Engineering News" and several other such engineering publications. I was luckly to puchase a retiring Ham's collection in the early 1990s which cast a different light on tube use during the 1940s-60s. The whole issue of whether to turn off or not was mainly determined by the criticality of the application and the difficulty of replacing the tube that might burn out.
Rob
"Monoblocks" = "monoblockheads" - it's "monaural amplifier"; "power output tubes" not "power tubes" & "patch cords" not "interconnects!" "Passive preamp(lifier) is oxymoronic!
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Follow Ups
- RE: Forgetabout tube ratings. - R. Mercure 08:36:06 10/08/10 (2)
- Some good points... - Allen Wright 10:36:40 10/08/10 (1)
- RE: Some good points... - unclestu 15:31:51 10/22/10 (0)