10 Aug
2014
10 Aug
'14
3:31 p.m.
On 08/10/2014 02:00 PM, Tony Duell wrote:
As with 12.6, 6.3, 25.2 volt units, there's an expected filament/heater
voltage. Since I know of no other 0.625V filament/heater tubes, I
suspect that it was basically a "might as well put it here" decision.
The loctal base 7xxx 14xxx, tubes, aren't rated for a nominal 7V or 14V
heater--they're 6.3 and 12.6. ISTR that not every 2xxx tube has a 2-2.5
volt filament--I'm trying to recall which it is, without a manual, but
my mind is failing.
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.
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). But
the 6N6 is an oddball dual-internally-direct-coupled triode. And the
6J6 is a dual common-cathode triode. But the 6H6 is a dual diode.
Trying to methodically make sense of this stuff is the road to madness.
1V2 = HV
rectifier diode; One of those odd tubes whose name doesn't
match its filament voltage. The 1V2 takes a 0.625V at 0.3A on the
I thought '1' was defind as >0 to <2V filament voltage. 0 was reserved
strictly for cold cathode vavles/tubes. IOn any case, I find the US valve numberign system
very irritating. It
tells you almsot nothign abotu the valve. The heater voltage number has
incosistnecies (like the use of 7 and 14 to mean 6.3V and 12.6V on a
loctal base -- msot fo the time). The last digit is supposed to be
something like the number of useful elemenets. But then a 6C4 is a simple
triode, so is a 6J5. I was told you count the metal shell in the last
case for some odd reason. I've foudn that if I know what hte vlave is, I
can find a justification of the number of useful elements, but trying to
deduce waht is is fro mthe code is impossible.
Like computer opcodes (not mnemonics), you just memorize them. Or go to
a manual.
--Chuck