19 Jul
2010
19 Jul
'10
11:24 p.m.
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.
To nitpick, not entirely true. In the original RCA system, U means
unit, V mean vacuum tube, and the 201 means it is a type 201. The A
indeed means the improved version. Capacitors were UC, resistors were
UR, and so forth. I think the type numbers were unique - there are
UV-201s, but I do not think there are any UR-201 or UC-201, for
example.
Yes, RCA themselves renamed the tube 01A, but this was after the
independents hijacked the system. They did so very effectively, and
even RCA fell in line by the early 1930s.
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.
Be careful, here. Specialized and transmitting type numbers were
indeed in their own world, but almost all US manufacturers stuck to
the system for receiving types. Hytron was no exception. A Hytron 6SQ7
will be an industry standard 6SQ7. Considering all of the
subcontracting and tube swaps done by RCA and the independents, even
back in the 1930s, it was extremely wise for everyone to stick to the
rules.
Raytheon had their CKxxx numbers, which they carried
over to the
solid-state world (remember the CK722?).
Once again, be careful. For receiving types, Raytheon used the same
system everyone else did. Occasionally they would put their vanity
prefix on a high quality premium tube (CK-36 is a standard 36).
On the other hand, 1D5-GP is a pentode; a 1D5-GT is a
tetrode.
This is one of the very few times the industry really broke their own
rules. There are only a few instances of this happening, and the
mostly deal with battery tubes all around 1933 or so. Past these few
screwups, receiving tube number duplication was pretty unknown in the
US, save a few times a European or Japanese type was unofficially
slipped into the system without industry approval. Those tubes are
almost never seen today.
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.
You mean UV-866, correct? Hehe...
As I said, it's like Boston.
Ironically, yesterday I was in Boston buying and selling tubes. And of
course I got lost after straying from Mass Ave.
So, yes, the US system has a lot of quirks and burps, but for the most
part, the consistency from even the early days thru the end was very
impressive. The US truly is (was?) the land of standardized parts.
--
Will