Got myself a Heil headset for the laptop as the built-in mic picked up room noise. So, I figured it was time to try a QSO on QO100 even with the floating (frequency wise) Pluto. And – success! I had a short QSO with a German station.
Just waiting for some small signal diodes to arrive before I glue the GPSDO output to the Pluto. There is a modification that involves removing the 40MHz TCXO and connecting an external source but the Leo Bodnar GPSDO output is 3.3V, too much for the chip in the Pluto. The mod involves two diodes in antiparallel to earth, plus a capacitor between the Pluto chip and the diodes, and another between the diodes and GPSDO. Hopefully that will work and the surgery on the Pluto does not consign it to the scrap pile! The GPSDO I have has two outputs, one 25MHz to the LNB, and one 40MHz for the Pluto.
I still need to sort the dish as signal strengths are still below where I expected. I am also concerned at the filter/pre-amp because it does not draw as much current as it is supposed to – it works but I wonder if there is enough drive. It may be perfectly ok but the next step has to be locking the Pluto so it doesn’t wander all over the place.