[ARC5] A Tube Puzzle

[J. Forster]

>      I can't find the characteristics of the 2C51/5670 but
> suspect its a transmitting or special purpose type although
> it looks like a conventional dual triode.

In the APN-9A it is used as a Flip-Flop...  I think.

> The system of
> specifying tube type numbers was established in the early
> 1930s at a time when there was a profusion of new tubes and
> no systematic method of numbering them at all.
> Unfortunately, it didn't work that well partly because there
> were too many new types and some of them did not fit any of
> the catagories in the original numbering scheme. Locktal
> tubes are among these. They followed approximately the
> original system by using approximate filament voltages.
> Philco also made tubes with non-standard types like XXD and
> XXL.
>      Transmitting and special purpose tubes do not seem to
> have ever followed any system, nor did Western Electric for
> their tubes.
>      The four digit number system used for ruggedized,
> military, and other specials also follows only a rough
> separation of types, my memory is that long-life tubes have
> six-thousand series numbers.
>      The W following the type indicates the tube was made
> for a government contact or contractor.  It may or may not
> have had to meet other than standard tolerances.

I believe W signifies a ruggedized tube for higher vibration service.

-John

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>
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>
>