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Click on the links above to follow 2E0IYN & G4XRA on their quest to reverse  engineer the world of 1980's radio

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Zycomm FM5016 CTCSS Circuit

 

There is a  add-on board which is an obvious retro-fit, as it’s fixed in place by double sided sticky foam.

Circuit board

 

After some investigation on Google we found that the IC-107 chip was a custom one supplied by an American company called Communication Specialist who discontinued thee type of products

https://www.com-spec.com/

The info comes from a website called Repeater Builder

https://www.repeater-builder.com/com-spec/com-spec-index.html

There were a lot of models of tone generators listed, but after further searching identified it as a SS32 card from the picture on the Repeater Builder web-site

A close-up of a circuit board

 

 

A diagram of a computer component

The tone is set by dip-switches:

A white rectangular object with black text

 


During Testing, we found that the "Ian" radio did, in fact have a different model of tone generators fitted, we identified it as a TS32 card - once again the info was foundon the Repeater Builder web-site

TS32-PCB

This unit also operates from, and reacts to, the received AF. It contains a filter to remove incoming sub-audible tones, and a tone squelch circuit