[Boatanchors] Octal versus Magnal?

Chuck McGregor cbmcgr at gmail.com
Wed Jan 8 14:00:36 EST 2014

Jim & David-
The socket generally called Magnal has 11 pins in a 1-1/8 inch diameter
circle and is used on the 2AP1 CRT and others.   The socket having 11 pins
on a ~3/4 inch circle, Amphenol Series 78, part #78-11S  does NOT mate with
Magnal plugs and lacks a common name.  Many users refer to all of the
Series 78 sockets having a center post similar to an octal socket, as
"octal with a number of pins".   While this may be an abuse of "octal"
which has its root as the number 8, it does provide a name for the socket.

Historically, Amphenol had Series 78 plugs and sockets from 4 to 12 pins in
manufacture and general use from the 1930's.  Socket #78-8S is identically
the octal socket pattern used for tube sockets.  The plug equivalent is
#86-CP8 and was described in their 1945 catalog as "8-prong octal".  The
same list describes plug 86-CP9 as "9-prong (octal style)"  and 86-CP11 as
"11-prong (octal style)".   The larger Magnal CRT socket was listed as
Amphenol part #49-SS11L and described as "Magnal steatite socket".
(steatite was a ceramic tradename).

Chuck K7MCG

On Wed, Jan 8, 2014 at 8:41 AM, qrv at kd4e.com <qrv at kd4e.com> wrote:

> I trust that Jim will not mind me sharing his interesting
> post from an eham discussion thread from last year:
> http://www.eham.net/ehamforum/smf/index.php?topic=84048.0
> ----------------------------------------------------------------
> The 11 pin plug/socket used by Heath and some others, and
> for relays, has a correct name:
> It is "magnal".
> "11 pin octal" is an oxymoron, because "octal" means "having 8"
> Don't ask how I know this.
> 73 de Jim, N2EY
> ----------------------------------------------------------------
> --
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