19 Jul
2010
19 Jul
'10
1:03 a.m.
On 18 Jul 2010 at 19:44, Tony Duell wrote:
Is it just me, or are the common US valve numbers
pretty much
meaningless. The common UK/European ones, used by Philips/Mullard [1]
can be easily decoded to give the heater rating, electrode structure
and base type. US ones don't seem to give the electrode structure in
any meaningful way, even though that it probably the most important
thing [2].
It depends. 0xxx = cold-cathode, gas filled, 6xxxx = 6.3V heater,
12xxxx = 12.6v heater, of course. 7xxx, 14xxx, loctal versions. The
last number is generally the number of elements in earlier devices,
but that's a give-or-take. So 5Y3 and 5U4 are both directly-heated
cathode full-wave rectifiers. 5 or 6 = beam power tube or triode
with dual diode section. 7 = indirectly heated cathode pentode, or
combination oscillator-mixer (e.g. 6L7), also dual triode. 8 =
pentagrid converter (e.g. 6A8). But it's all approximate.
It's like navigating around Boston--if you lived there, you'd know
where you were headed.
--Chuck