6U8 vs 6U8A - is the difference only in heather Warm-Up time ?

[kagliostro]

Is the difference between 6u8 and 6U8A only in heather warmup time ?

http://frank.yueksel.org/sheets/168/6/6678.pdf

https://frank.pocnet.net/sheets/049/6/6U8A.pdf

Thanks

Franco

[VMS]

According to this page the answer is yes:


http://www.r-type.org/exhib/aaa1389.htm


http://www.r-type.org/pdfs/6u8.pdf


http://www.r-type.org/pdfs/6u8a.pdf

[kagliostro]

Thanks VMS

Franco

[PRR]

They may be the same.

In series-string heaters it is best if all the heaters warm-up at the same rate. A standard rate was picked, and some (not all) the "A" tubes meet that spec. However the spec was picked to be similar to how most existing tubes warmed-up. I suspect only a few extreme types, or odd makers, actually had to  change their heater designs.

Huh. The magazine Popular Science ran a very fictional story/article about the change. Because it is a boring subject, the author jazzed it up with a horse-betting story and Runyon-esque slang. This may not read well if you are not an older American, but you will get the idea. "11 seconds" is a simplification; I inserted the actual spec.

[kagliostro]

Thanks PRR

I like very much your explanation (and saved the article in my archive)

Franco