„QSB“ with Pluto?

Hello YLs and OMs,

I am using a typical Pluto setup (Pluto —> Bandpass Filter —> Pre-Amplifier —> SG-Lab PA V3) —> Antenna), controlled by the latest developer version of SDR Console (3.0.26).

Since some time now I do have a kind of QSB-like effect on my QO-100 signal. While the reception remains constant, my own signal gradually goes down by up to about 10dB. After a while it goes up again, sometimes it takes a little longer to do that. I have checked all components of the setup (amplifiers, cables, antenna) and it seems to be the Pluto itself.

Anybody else ever experienced this behaviour? Any suggestions?

Thanks, best 73 and stay safe!

Holger ‚Geri‘, DK8KW

Achim,

thanks, that is a helpful idea. I do have a LimeSDR around somewhere and will feed a signal from a directional coupler between the Pluto and the bandpass filter into the lime to monitor the output of the Pluto.

Vy 73

Holger ‚Geri‘, DK8KW

Hello all,

The problem seems to be solved now.

I had some buffer overflow problems with SDR Console and those hiccups in the software seemed to have led to the fluctuating power. Simon, G4ELI did some modifications to the software and, to support my 10 year old Q8400 CPU handling all the signals in my computer I installed a "vintage" NVIDIA GeForce 8400 graphic card that I had laying around. Since then, the CPU load went down and, at at the same time, the "QSB"-problem was gone.

Vy 73

Holger 'Geri', DK8KW