QRSS with Si5351

As I mentioned in my previous post, I have been experimenting with the Adafruit Si5351A Breakout Board and today I thought I would do some frequency stability tests using the QRSS tool Spectran. This tool will enable me to see variation in frequency with sub-hertz resolution.

Using the NT7S Library I setup the following in the loop() section of the Arduino code

Code Snippet

As you can see, all I am doing is setting the frequency to 7.083.000 Mhz (in the 40 Meter band), then after 10 seconds, I set the frequency to 7.083.001 Mhz which is just 1 Hz higher for 5 seconds and repeat. The plot below using Spectran is showing the clock board being received by my FT-817 transceiver with my dipole antenna. The bread board was in the house about 20-30 feet from the antenna with just a 4 inch piece of wire as it's antenna. From left to right, I had been running it for over 10 minutes then I powered it down for about 2 minutes and then powered it back up. When it powered up again, it was about 5 Hz higher than before being shutdown, then after about 5 minutes it was back to where it was before I powered down (pretty cool!). The full width of the plot is 10 minutes and shows less than a 1 Hz variation over that period (again, very cool!).

I would say that this board with a bare Arduino chip would be a great option for a QRSS beacon module as well as the other uses we have discussed. The more I use the Si5351, the more I like it.