CMOS Programmable CTCSS

Hi All,

A while back I had made my own CTCSS tone encoder circuitry to fit to a couple of ancient 2m radios so that they could access the local repeaters in my vicinity. Links to those postings are as follows :-

https://charlietangodxgroup.forumotion.com/t3088-homebrew-ctcss-tone-encoder

https://charlietangodxgroup.forumotion.com/t3478-homebrew-ctcss-tone-encoder-for-my-yaesu-ft290r


I've had quite a few enquiries about these circuits since posting them from many people around the world and glad that I was able to help others drag their old radios into the modern world too.

However, I've still had a fair few people ask about 'programmable' units and always responded with links to typical microprocessor circuitry which as mentioned before does require the use of a computer, suitable programmer and the skills to perform the required procedures. Feeling that I hadn't helped much I scoured every resource I could think of to see if there was a 'programmable' alternative circuit that would provide a solution....

Luckily I came across an article by IZ1ANS - Antonio Iuliano in an old edition of VHF Communications magazine published back in 2010.

An archive copy can be found at the wonderful World Radio History with the following link :-

https://worldradiohistory.com/

Just go down to the menu on the left until you get to 'V' then select the 'VHF Communications' link and look for Edition 2, 2010.


I'll include a couple of pictures clipped from that article here just in case it helps others further.....

Firstly the Schematic/Circuit Diagram :-




Secondly the 'programming' or jumper settings for appropriate CTCSS tones :-




It's quite an ingenious circuit utilising a typical or ubiquitous 'watch' oscillator crystal along with use of an 8-bit pre-settable binary counter. Set the jumpers for the tone you want and away you go.


Anyway, more of my 'waffle' but hopefully it comes in use to someone at some point.

Plus I can just simply provide a link to this posting now the next time I get an email enquiry.


All the best,
Victor

M7VIC