Tricky to set drive level, SDR Console to PlutoSDR

  • 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

  • Hi Chris,

    as you can see in the SG-Lab data sheet, the vox already works with 1mW input, so it only needs a low level to switch PTT. Your CN0417 module with approx. 20dB ampli generates a maximum of 50mW from the approx. 2mW of Pluto, which has been attenuated by 6dB. This is perfectly sufficient to fully drive the PA. Depending on the transmitting antenna used, the level on the QO-100 is much too high and the Leila is activated. Here you should set the maximum levels for Gain, Drive, etc. accordingly in the settings "Transmit - Options - Audio-in - Gains".

    I hope this is of some help, if Mr. Google translated everything correctly :)