A Cuban ham radio story: Arduino Arcs

Monday, June 20, 2016

Arduino Arcs

Yes, I got bitten by the Arduino fever.

Arduino-Arcs is the name for a project I'm baking up in github, you can visit it here, the name stand for "Amateur Radio Control & Clock Solution".

That's a pretty way to say it's a ham radio front panel interface solution with VFO+XTAL+BFO frequencies generator.

In a modern radio transceiver you need a brain (MCU) than controls the logic for switching Xtal filters, band-pass filters, mode changes, etc. and also show in a pretty LCD the info for the user.

This MCU or brain usually controls some DDS or PLL in ancient radios, recently the homebrewers community find a good use for the AD9850/51 from Analog Devices but it has some tricks as the power drooping as you increase freq and the harmonics and images...

Then NT7S make the Si351 IC popular, this is a clock (TTL levels not sine wave) with multiple outputs and a range of ~8 Khz to 160 Mhz with sub hertz resolution. In the basic configuration you have 3 independent outputs of RF that can handle easily the VFO, the XFO and a BFO for any single or dual conversion radios.

Sure it's has it's own problems, with the harmonics as it's a square output device but that's nothing to worry about if you put a LPF unit in between.

When you compare the AD9850/51 module with the Si5153 solution you find a few plus:

3 outputs
Stable level on the outputs (in the AD9850/51 it changes with the freq)
Way lower price ~$2 for one Si5351 with 3 outs vs. almost $20 for a single AD9850/51

Juan Carlos WJ6C and other Cuban Hams like Axel (CO6ATL) and Heriberto (CL2KMK) was playing with some public Arduino sketches on the net and they build some kits and part like this.

Of curse with the Si5351, then in June 2016 I join the team to help with the Arduino programming and the result is the code you can enjoy on the github page mentioned earlier in this post.

Some more pictures about the new sketch, design and PCB courtesy of WJ6C, CL2KMK & CO6ATL