Here is a small update regarding my band hopping picaxe controlled wspr beacon.
I took the beacon of air the other day to do some revisions to it’s circuitry. And in this context figured out that I was in need for a filter to clean up the square wave shaped signal from the 10MHz reference oscillator, the GPSDO MKII. I did a little googling and found an interesting circuitry drawn by Jerry Mulchin – N7EME. The reason for needing this filter is that I have a passive frequency trippler for clocking the DDS-60 @ 30MHz, and this tripler need a sine wave to work right.

There is still some work to be done before I can put the beacon back on air. But as they say in broadcasting; Stay tuned, will be right back after….

PCB measures 60x20 mm and parts are SMT

Schematics

Measuring reflection (S11) with the minivna. Return loss is more than 26dB @ 10MHz.

Measuring transmission (S21) with the minivna. 1dB insertion loss @ 10MHz and cout-off at 12MHz.