I have been playing with an arduino, gps pcb, si5351 and a tx running 1 watt from two BS170's.
Attached photo shows MEPT detail.
Works well on QRSS and now I have programed to run WSPR as well.
I will be posting a web site soon where all my design and code will be available.
Antenna is a multiband vertical and I am running WSPR on 7Mhz at the moment.
Hope to see your spots.