[Boatanchors] PERMANIC Microphone

Mike Langner mlangner at swcp.com
Wed Mar 9 21:43:14 EST 2011

Hello !

Let me guess.

Early broadcast dynamic microphones used a DC current operated field coil to
make the magnetic field.

Indeed, in the very early days, this current would cause the microphone to
become quite warm, hence the phrase "hot mic!"

I bet this is what you have.  If so, it's a great part of broadcasting


(lifelong broadcast engineer -- my career started in 1958!)

Mike Langner
929 Alameda Road NW
Albuquerque, NM 87114-1901

(505) 898-3212 home/home office
(505) 238-8810 cell
mlangner at swcp.com

-----Original Message-----
From: boatanchors-bounces at puck.nether.net
[mailto:boatanchors-bounces at puck.nether.net] On Behalf Of Bob Peters
Sent: Wednesday, March 09, 2011 7:28 PM
To: boatanchors at mailman.qth.net; boatanchors at puck.nether.net; 'Discussion of
AM Radio in the Amateur Service'
Subject: [Boatanchors] PERMANIC Microphone

Does anyone on here know what a PERMANIC MICROPHONE is ???? I just bought
one of e bay...Manufactured by Quam the Speaker company. No one at Quam has
ever heard of it...It looks like about
1940 vintage... it is NOT a speaker...IDEAS???

Bob W1PE

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