Valves/Tubes was: ez80
cclist at sydex.com
Mon Jul 19 17:03:02 CDT 2010
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.).
The problem with the pre-WWII receiving tube system is that there
were several systems. For example, the hugely popular UV201A means a
type 01 triode, with a UV base and a thoriated tungsten (A) filament.
In the RCA handbooks, the tube is simply listed as type 01A.
Each manufacturer also had their own system, so for instance, Hytron
had HYxxx numbers, in addition to their own "GTX" ceramic based
versions of popular tubes.
Raytheon had their CKxxx numbers, which they carried over to the
solid-state world (remember the CK722?). In 1934, the Radio
Manufacturer's association set in place a new system, which is the
one we know now (first number = filament voltage, letter (assigned
like license plates, in order of introduction), number of functional
electrodes. Like license plates, the numbers ran out, so
manufacturers began using the last number on an as-needed basis. So
we have 6B4G = power triode, 6B5 = dual internally-coupled triode,
6B6 = duplex diode+triode, 6B7 = duplex diode + pentode, 6B8 = duplex
diode pentode. On the other hand, 1D5-GP is a pentode; a 1D5-GT is a
Of course, a 12AP4 doesn't have a 12v filament, but is a 12" CRT with
a 2.5V filament and P4 phosphor.
Transmitting and industrial application tubes are sui generis with
lots of bizarre combintions. For example, an 866A is a mercury-vapor
rectifier with a 5 amp, 2.5v filament and a 10KV PRV rating and a
1000 ma peak current capacity. On the other hand an 866Jr. is a half-
sized version--sort of. The Taylor version has a 3 amp. filament and
3.5KV PRV with a 250 ma. peak current. The Hytron 866Jr has a 3 amp
filament, but a 5KV PRV and a 500 ma peak current.
As I said, it's like Boston.
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