Using the two outputs from the si5351 should work fine.
Spectral purity would not be an issue, the square waves just make harmonics
of the si5351 outputs and are easily filtered out by the front end of even a very old radio.
Signal would be a bit weird in that it would only have one sideband,
but I doubt those old radios are smart enough to notice.
Jerry, KE7ER
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On Tue, Nov 7, 2017 at 03:07 pm, Michael Hagen wrote:
Also, one of my interests is restoring vintage radios. To align theses, it is helpful to have a modulated signal, as there is no bfo. Rather than build a modulated output stage, what about using clk1 for the main carrier output, and if you want modulation, have clk0 and clk2 track with clk1, but offset by say +/- 700 or 1000 hz. If these outputs were attenuated by 6 dB relative to clk1, and mixed, they would approximate a 100% AM modulated signal. I know from a spectral purity standpoint things will not be the greatest, as the raduino does not output a sine wave, but you would at least have a tone you could hear on a receiver without a bfo.
