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From: hrs1@cbnewsi.att.com
Newsgroups: comp.dcom.telecom
Subject: Re: 500/2500 Handsets
Message-ID: <11198@accuvax.nwu.edu>
Date: 22 Aug 90 02:39:10 GMT
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X-Telecom-Digest: Volume 10, Issue 586, Message 6 of 11


In article <11093@accuvax.nwu.edu>, roy@alanine.phri.nyu.edu (Roy
Smith) writes:

> 	OK, here's a question that's been bothering me for probably
> about 20 years.  Why, on a standard 500/2500 handset, does the
> microphone just drop in but the speaker have screw terminals?

The "standard" 500/2500-type handset is/was the G-type handset.  It
originally had a U-1 ring armature receiver, but I forgot the code for
the carbon trans- mitter.  Note the use of the terms "receiver" and
"transmitter", rather than speaker and microphone.

The receiver is an electromagnetic device, and rarely fails during the
life of the telephone set.  The carbon transmitter depends on the
action of the carbon granules, which have to remain mobile.  They have
a tendency to pack, however, especially if the fone is used in the
same position for a long time.  This often happens in a wall phone.
While this can often be fixed by banging the handset against a hard
object, it is an easy matter to open the handset and slip in a new
transmitter capsule.

New telephone sets now usually have electromagnetic ot electret
transmitters, and the handsets cannot any longer be opened.


Herman Silbiger