wb8nbs created an Si5351 powered signal generator.

This compact signal generator is packed into a tin that’s just slightly bigger than the ones those curiously strong mints come it.  It uses a breakout board with Si5351 and a TCXO from Etherkit.com.  A TCXO (Temperature Compensated Crystal Oscillator) allows for very accurate frequency.  The unit brings out all three signal outputs, individually programmable for frequency (500 Khz to 160 Mhz), sweep width and limited level control. There is a Teensy LC for control using Si5351 libraries from Jason Milldrum NT7S. The battery and charger are out of a cheap cell phone booster.

You can read more about the project on wb8nbs’s blog.  A zip archive of the code for the project as well as a schematic can be found here.