"Scott Dorsey" wrote in message
...
Richard Knoppow wrote:
The 50L6 is NOT a relative of the 6L6. It is a
pentode
power tube with 10 watts of plate dissipation compared to
19
watts for a 6L6. The 6L6 puts out about 2.5 times the
power
when operating as a single tube Class-1A aplifier. Other
characteristics are also different.

Yeesh! That is not good at all! That is a very
misleading number in
that case.

What about the 25L6 then? I have pitched a lot of 25L6
tubes
over the years because they showed low transconductance
compared with a 6L6.
--scott

Its identical to the 50L6 except for the heater voltage
and current.
The numbering system for tubes was intended to be
systematic but broke down pretty quickly because of the
plethora of new tubes. The earliest system was chaotic with
numbers but also prefix letters usually indicating the
manufacturer. For instance, RCA prefixed its tubes with UX
so a UX-210 is a 210 tube made by RCA but others also varied
the numbers, I think DeForest used 5 in place of 2 so a
Deforest 210 became a 510. The number-letter-number system
began sometime around the early to mid 1930's. I used to
know the exact date but its evaporated. Note that while the
first number usually indicates the filament voltage that is
not always true. For instance, Philco and others made
"locktal" tubes, a variation of the octal type but with
plain wire leads and a sort of locking base. These usually
have a 7 as the prefix of the type number but mostly have
6.3V filaments. As usual in life chaos reigns supreme.


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Richard Knoppow
Los Angeles
WB6KBL