Valves/Tubes was: ez80

[Tony Duell]

> 
> On 19 Jul 2010 at 21:11, Tony Duell wrote:
> 
> > 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.).

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

> 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