Improving frequency stability

  • Hi everyone,

    F4HVQ Sebastien and first time on this forum. Hope this thread is in good category.

    I built my QO-100 station in order to use it on NB part:

    - SSB

    - digimodes (FT8/FT4, Winlink, HSM, ...)

    In attachment here is the station diagram.

    With this configuration SSB mode work well BUT digimodes DONT, especially Winlink and HSM !

    I suspect a lack of frequency stability.

    What do you think ?

    Are there any solutions to improve frequency stability ?

    Today LNB is NOT locked on clock reference as Adalm Pluto with the GPSDO.

    Is there a system to use same reference clock (here Leobobnar GPSDO) to feed Adalm Pluto AND LNB ?

    Is this LNB compatible ?

    Thank in advance for your help

    73 de F4HVQ Sebastien

  • HB9SKA

    Changed the title of the thread from “Imporving frequency stability” to “Improving frequency stability”.
  • I operate mainly DATV on the wide band portion, but I lock my Pluto and my LNB to a single dual output Leo Bodnar GPS disiplined oscillator. The LNB at 25MHz and the Pluto at 40MHz. I filter the 25MHz LNB output through a low pass filter, but saw no difference both with and without it. Both work fine. You may need to ask Bodnar what settings are needed to give the desired frequencies, and some combinations may be mathematically impossible with one dual output device. 25 and 40MHz is not a problem.

    With a Version D Pluto it's easy to *THINK* it's locked to an external reference when in fact it's not. Test to make certain it's actually using the external input.