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Phone calls on the radio....

Started by twocvbloke, May 12, 2012, 10:32:05 AM

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twocvbloke

I was playing a game today on one of my computers, and it had a phone-in type soundtrack playing away in the background, some of the calls sounded like they were made over phonelines, others recorded in a studio and just tweaked with to remove the bass and mid tones, and it got me thinking, back in the day, who though of putting calls onto the air, and live calls no less, and how did they do it?

Today of course it's all digital and they have dedicated desks to do it, but when talk-ins were in their infancy, I can't think of how it would have been done... ???

Phonesrfun

It's done with what is called a phone patch. 

Radio stations have been doing it for years.  We had phone-in talk shows on the radio back when I was growing up in the '60's and they have probably been doing it even back to the 20's when long distance telephone calls used to be transmitted between here and your part of the world in the UK via HF radio links.

A phone patch is a very simple passive device.  Passive, meaning no amplification.  It uses a matching transformer and perhaps a couple of resistors and capacitors.  All it does is match the relatively low impedance of the phone line to the higher impedance of the microphone input impedance of the radio transmitter, and to provide for controlling the volume.

Phone patches were once a staple in a ham radio station, since hams in one part of the world could seek out a ham in another part of the world and provide a "free" phone call for a friend or relative via the ham radio link.  With long distance rates so low these days and the internet and so forth, this method of calling someone is no longer used much.

As far as who though of it?  I don't know.  Could have been anyone.
-Bill G