Tricky drive level setting for SDR Console to Pluto, QO100

Chris Wilson

12 February 2022

I wonder if anyone can kindly help me with a drive issue I am having with my PlutoSDR and transmitting to the QO100 satellite via the narrow band transponder using SDR Console please?

Recently I am finding setting the drive level is incredibly tricky. Using the Tone or Tune functions in SDR Console a tad too much drive level and the Leila, the satellite's too great a signal level warning is triggered. I reduce drive until it is no longer triggered and all is OK for some seconds, then it is triggered again, as if my power is increasing of its own accord.

Once I find an acceptable level by very fine manipulation of the drive slider but I then find that after a period of reception there is no longer enough drive to set the Pluto / amp into TX again.

This appears to be a recent problem, as a while ago when I was on the narrow band transponder with SSB I didn't seem to have so much of an issue.

My set up is Windows 7 64 bit, SDR Console V 3.1, LAN connection to my Pluto at the base of my 1.8 meter prime focus dish. The Pluto is driving an Analogue Devices CN0417 pre amp driving an SG labs 20W amp via a 6dB attenuator, which in turn is triggered by its VOX PTT. The SG Labs amp then feeds the POTY antenna via a short length of low loss co-ax.

MAYBE the attenuator is between the Pluto and the CN0417, I can't reliably recall, and I am at work.

My own, novice, thoughts are that to trigger the SG labs amp via VOX is needing enough drive power to put its output around the trigger point of Leila. Does that sound feasible? What about the rise in output when TX'ing, and the fact a signal level adjusted down when operating with Tune or Tone to stop triggering Leila becomes insufficient to set the ensemble into TX at the next transmission?

Thanks for any advice. I could JUST get a signal on SSB with only the CN0417, before I got the SG labs amp. I wanted a good deal more power as I also run the set up on DATV on the wide band QO100 transponder. Best regards, Chris, 2E0ILY


Best regards,
Chris mailto:chris@...

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