11 Aug
2014
11 Aug
'14
8:52 p.m.
I suspect that the reason for the strange numbering of
US tubes is mostly
due to its age and diversity. It's been a long time since UV201s or 76
triodes, and the chart fills up--or runs out. So you get inventive.
Well, yes exactly. The 10 through 99 line pretty much filled up (yes,
nearly all the numbers that are never seen were indeed made for a
short time - some are very rare), and simply going into the hundreds
would not have worked, simply because of all of the vanity prefixes at
the time (thank you, RCA/Cunningham). The 1935(ish) RMA scheme was
*never* intended to be perfect and describe the device exactly - I
think it even says so in the rulebook. Its *big* point was to register
device numbers so duplicates and conflicts would be avoided -
something that was far too common during the early 30s Wild West
years. The loose system gave the registrars something the work with so
they could encode an alpha character (later two) into the mix, so
there would be a very low chance with fouling a designation with an
existing or planned part. In this, it succeeded in a large way - there
were *very* few issues with conflicting numbers.
Or take the 6x6 tubes. 6K6 and 6L6 are beam-power
"pentodes" with the
beam-forming electrodes internally tied to the cathode. Likewise for the
6M6 (which, in spite of the name, is a glass-envelope tube).
Bad example, or a typo? 6M6 is an unregistered type. (So is 6X6, but I
assume your little x is a wildcard).
Like computer opcodes (not mnemonics), you just
memorize them. Or go to a
manual.
Yes. It is not hard when the guys worked with them day by day. And if
they did not have the number-function thing memorized, they probably
should not be fucking with the circuit in the first place.
--
Will