deltadave

You are very welcome Stan! Attached photo shows the two types of module I used (the AD9851, and the SI5351). The photo of the AD9851 shows the module before the 30MHz xtal was desoldered/removed.

Schematic for the VFO described above.

Attached GCB program is the basis for a tuneable sinewave VFO based on an cheap AD9851 module from China. Output frequency is settable in 1Hz steps across the entire range, using a 600pulse per revolution optical shaft encoder. To simplify the maths needed to control the AD9851 I dumped the stock 30MHz reference crystal fitted to the module, and used instead an SI5351 clock generator to generate the reference frequency for the AD9851. (Using certain other reference frequencies can make the frequency...

And here is the schematic. (Updated to Ver2 as some microcontroller pins were mis-labelled on Ver1)

And here is the schematic. (Updated to Ver2 as some microcontroller pins were mis-labelled on Ver1)

VERSION OF VFO WITH QUADRATURE OUTPUTS (2.4MHz - 125MHz) Great Cow Basic code for controlling a VFO based on ADAfruit SI5351A VFO module. VFO provides continuously tuneable (square wave) quadrature outputs from 2.4MHz to 125MHz. (It actually generates an output all the way up to 225MHz, but quadrature output accuracy has not been verified at higher frequencies) Frequency is set using an optical rotary shaft encoder. Schematic for the SI5351A VFO is the same as that used for the VCO Range analyser...

Great Cow Basic code for controlling a VFO based on ADAfruit SI5351A VFO module. VFO provides contiguous (square wave) output from 60kHz to 225MHz. Frequency is set using an optical rotary shaft encoder. Schematic for the SI5351A VFO is the same as that used for the VCO Range analyser (above) VFO complementary outputs are on CLK0 and CLK1 ports of SI5351

Great Cow Basic code for controlling a VFO based on ADAfruit SI5351A VFO module. VFO provides contiguous (square wave) output from 60kHz to 225MHz. Frequency is set using an optical rotary shaft encoder.