20 Jul
2010
20 Jul
'10
7:03 p.m.
On 19 Jul 2010 at 21:11, Tony Duell wrote:
Sorry, I wasn;t clear. I didn't mean that the metal envelope version had
a diferent number to the G and GT versions (not even the US valve numbers
would be that stupid!). What I meant was that the octal based valve had a
final digit that was one greater than a similar valve on a differnt base.
For example, IIRC, the octal double diode triode is (for example) a 6Q7.
The loctal one is a 7C6. An octal beam tetrode output valve might be a
6V6, but the local one is a 7C5. A 6H6 is n octal-based double signal
diode, there's a B7G one (7 pin minuature) numbered 6AL5 Note that the final
digit of the loctal/B7G is one less than that of the octal.
I was told this was beacue the octal version included the envelope as
element (because of the metal valves that had it connected to pin 1 (?))
whether it was there or not
And IIRC for octal valves, the metal envelope
(early octals being
those RCA metal things, of course) counted as an element.
I don't believe so. 6L6 = metal beam power tube; 6L6G = glass
envelope. (not to mention GT, GA, GB, etc.). Of course, a 12AP4 doesn't have a 12v filament,
but is a 12" CRT with
a 2.5V filament and P4 phosphor.
Sure, but I don;t think any manufaturer tried to include CRTs in their
valve numbering scheme. I remember the Mazda CRT code, it started with a
'C' (for CRT :-)), then a letter giving the type of deflection used (M or
E), then a thrid letter giving the focusing methof (again M or E), then 2
digits giving the screen size (diameter for a circular CRT, diagonal for
a rectangular one, in inches), and finally another pair of digits to
distiguish between otherwise indencially-numbered devices.
So a CME1703 is a 17" CRT with magnetic deflection and electrostatic
focussing.
-tony