[Milsurplus] Mystery Signal Corps (?) module

[Peter Gottlieb]

2600 Hz was the standard supervisory tone frequency and I've also heard of 2400 in cases where each side required separate control and there were cases when there wasn't audio path isolation. Using the tone eliminates the need for a copper connection for circuit busy/idle control. There might be tone oscillators and/or detectors associated with the relays. 

No idea what this particular device was specifically for though. 


Peter

> On May 3, 2017, at 12:33 PM, Nick England <navy.radio at gmail.com> wrote:
> 
> Any ID on this?
> http://www.antiqueradios.com/forums/viewtopic.php?f=5&t=320645
> 
> The binding posts look like some wireline device.
> 
> Nick England K4NYW
> www.navy-radio.com
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