Adalm PLuto external ref 40Mhz from Down converter and now I drift a lot.

  • Dear All ,

    I know this was answered before too ( tried to find something but to no avail) , But I am a bit perplexed so if someone can shed some light on things I would be happy. (rev C possibly )

    I have the Amsat down converter with the 40mhz output. I measured it all good. I made my cable(2 pin header to hoax to sma ) and directly connected it to the Adalm Pluto(external ref in port). But now it seems even more unstable than before.

    When I type this :

    # fw_printenv ad936x_ext_refclk <--

    ## Error: "ad936x_ext_refclk" not defined <--I get this ( what ? )

    I tried to enable external reference for the pluto.

    # fw_setenv refclk_source external
    fw_setenv ad936x_ext_refclk „<40000000>”

    fw_setenv ad936x_ext_refclk_override 40000000
    fw_setenv xo_correction 40000000

    then reboot.

    and now my transmission is drifting like crazy even with the external reference. and I can even see it before with the TSXO ( default config on the adalm Pluto I had no issue. ) (very rarely I was drifting that much )
    something like this :

    and at some points even worse.

    I hope someone can drop me a hint ,

    Thank you in advance

    5B4AKV , Alex