[SBE] Q 2 Cert exam - Loctal tubes

[Art Lebermann]

The Loctal tube design was developed by Philco and Sylvania (in 1939), in
an effort to compete with new tubes from RCA.  This design eliminated the
Bakelite base, and used pins through a glass-button base.  The "lock-in"
design was necessary to keep the tube in the socket.  They were not
designed specifically for auto radio use.  The "7" and "14" prefixes were
chosen to identify the tubes as Loctal types.  The "7" tubes had 6 volt
filaments, and the "14" tubes had 12 volt filaments.  You'll find specs in
the early RCA receiving tube manuals.

Art Lebermann
KGO / KSFO
San Francisco



> [Original Message]

> From: <A9xw at cs.com>

> To: <sbe at sbe.org>

> Date: 11/16/2007 6:57:54 AM

> Subject: Re: [SBE] Q 2 Cert exam

>

> As we know the Locktal was for automotive use, with 7 and 14 volt

filaments. 

>

> Henry   

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