CTCSS Encoder For Transceivers

This CTCSS tone encoder was designed for use with my Kenwood TM201B 2m transceiver. It uses the most *inexpensive* microcontroller on the planet; AVR Tiny11-6PC. The microcontroller is an AVR core microcontroller with minimum number of peripherals. Although this micro has an in built 1 MHz oscillator, the micro is clocked using a 32KHz XTAL to generate a stable clock. The internal oscillator is not calibrated and the clock varies with voltage and the temp of the device.

The unit is right now programmed to generate one tone but there is an option for four tones. The two IO pins of the micro are left aside for tone selection input. The tones can then be selected by the jumpers.

The Kenwood TM201B transceiver has an option of adding a tone board TU-3. The module is hard to find and expensive. After doing a lot of digging, a Kenwood engineer helped me with the TU-3 Datasheet.

Below is the schematic in PNG format. This is also available at github.

I have published the code on github under Attribution-NonCommercial-ShareAlike 4.0 International License.



ab9no said…
how can i get the parts for one of these,or buy assembled.
Chetan Bhargava said…
I did not get the PCBs made professionally. I plan to release the code and schematics.
Anonymous said…
Hi, do you have schematic and programming file?

Thank you!
Chetan Bhargava said…
Unfortunately I have lost the schematic and layout files. It was designed in Eagle. I will try to find and add it to my github account. I see a lot of interest in this so I'll think about a kit. Thanks for your comment. KG6NFG
Chetan Bhargava said…
I have redrawn the schematic in gEDA. Will be publishing it on github soon.
André C said…
Please send me your info at acme9283@gmail.com I am interrested to have one for my radio.
André C said…
Please send me the info you have ( schematic, source code , bin or hex file )
I need a module for my radio and commercial unit are too expensive.
André C said…
could you give the website info and files and schematic to buid my own ? Thanks.
Anonymous said…

Did you find info on your project ? Would be glad to build one for myself adn would also need the program, schematic and parts lists. thanks.