On 2017/02/28 1:26 PM, wrote:
On Tuesday, February 28, 2017 at 2:50:33 PM UTC-5, micky wrote:
In sci.electronics.repair, on Mon, 27 Feb 2017 15:36:52 -0800, Jeff
Liebermann wrote:

On Mon, 27 Feb 2017 16:38:10 -0600, wrote:

I have yet to find a decent chart which explains the reason for the
numbers/letters used on tubes. (For USA tubes).

I don't have an answer to your question. However, note that any
significant numbering scheme always falls apart as technical progress
advances faster than letters and numbers can be contrived to match.
For example, we started with 1Nxxxx = Diode, 2Nxxxx = Triode (BJT,
FET), 3Nxxxx = (Dual gate MOSFET), 4N = Optoisolator, etc. That
lasted about 10 years before devices arrived that could not easily be
crammed into the significant numbering scheme.

I agree with you here.

The JEDEC would have
been better off just starting at 00001 and counting up in sequence. It

I don't agree they would be better off. The system was valuable for
many early tubes and I didn't expect it to work forever. so I ignored it
when it didn't work. Numbers in sequence would have meant nothing,

OTOH, the relationship between a 6SD6 and a 12SD6 is clear. (I'm not
positive those exact tubes existed. It's been a long time.)

And the tubes in my father's battery powered tube radio, with names like
1au4 and 2-something, made it clear how they could run off of batteries.
(Unfortunately one of the batteries was iirc 46v, so I couldn't afford
to buy another one.) The radio also ran on AC, but was meant for civil
emergencies.

Someone, maybe my father, also bought a crystal radio, a 3-inch
diameter, 3/4" brown plastic box with holes in one side to listen
through, and a green wire with an alligator clip coming out of it. It
had a clear plastic rounded fluted tuning knob and only got one station
in Indianapolis, the strongest one I think. But one is enough, if we'd
ever been without power during an emergency. But I dont' think we ever
were.

would seem that the semiconductor people had not learned the lessons
of tube numbering, and repeated the basic mistakes.

As to 813 etc. I haven't found any all numerica names but I wouldn't
have thought the 8 referred to voltage. That I would have taken as some
subset of sequential numeric naming.

I suspect the very early tubes were simply numbered in order of development. My old Radiola uses an 80, a 171 and a bunch of 27s. The 27s are 2.5v filaments and the 171 and 80 are 5v.


My 1933 RCA/Cunningham Radio Tube Manual agrees. Pg 143:
--------------------------------------------------------------
THE NEW TUBE-NUMBERING SYSTEM

Type numbers for new tubes are now being assigned in accordance with the
new system adopted in the early part of 1933 by the Radio Manufacturers
Association. A new system was required because practically all of the
available two and three digit numbers have been utilized.

.... (description of the numbering system, as described above)

While these rules assist to some extent in classifying tubes by filament
voltage and function, the significance of the individual symbols will in
most cases be inadequate to identify the specific features of a tube.
--------------------------------------------------------------------

I love old manuals!

John :-#)#

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