Captures of PLL LNB drifts over time. WIth & without mods.

  • I only put the idea (not initial from me) of software drift correction in my raspberry setup and hope to make something a little bit easier. For me and for all of us. Thanks to you and thanks to all. That's the spirit of amateur radio ;-)

  • As long as you credit the person who has the idea and first working software correction setup i'm fine with that ;)

    'The frequency'


    "Perhaps someone will write an SDR code which will automatically track the beacon while receiving other signals ;-)"


    Congratulations to both of you!! Well done!! :thumbup:

    Peter Gülzow | DB2OS | AMSAT-DL member since 1983 | JO42VG

  • DB8TF

    Changed the title of the thread from “Capture of Octagon OSLO drift over 20 min.” to “Captures of PLL LNB drifts over time. WIth & without mods.”.
  • Hello! Very disappointed on my LNB mod with tcxo D75F 25.000. The beacon stays within +/-3khz around 10706.000, but frifts at every second, making the signal to chirp,not usable :( . Never drifts more than 2khz away even when wormed with solder iron, but the way it compensating it’s making it useless. I don’t understand why this happens, because i got to order D75F after reading about succesful results with 27MHz LNB’s


  • A TCXO should not be "controlled" at all...

    Maybe these blocks include a fixed crystal and a PLL that is programmed to output the frequency that you order?

    In that case it could indeed expose the behavior of that PLL (either an analog loop, a digital loop with DAC), or a DDS....

  • Hallo...

    oh.... i see this now.... JUST TO NOTE....

    is there anyone here who wants TO MOBBING me?


    THATS NO HAMSPIRIT ....!!!


    SORRY ... and PLEASE THINK ABOUT....


    HAMRADIO SPIRIT AND OPEN SOURCE is needed ....

    NOTHING MORE ....


    73 de DG0OPK

  • dg0opk I hope my post didn't offend you in any way. I never said that my source of information was your article about LNB mods. Just trying to find out why there is so much difference between TXCO from same series but not the same frequency.

    DD0KP I hope is not the case because i bought it from digi-key, part number CW654CT-ND Connor-Winfield #D75F-025.0M , paid 14.49$ + taxes...

    My intention is to help other hams not to spend money and (most important) time trying to use D75F 25MHz TCXO, like the one in the picture from my last post, with RT320M. It could be a both-side problem , TCXO+LNB, not figure-it out by now. I will try to send a e-mail to ConnorWinfield to get the whole picture.....


    73 de YO9HZN

  • I will try to send a e-mail to ConnorWinfield to get the whole picture.....

    It would be very interesting to know if these modules are only a TCXO (with a crystal operating at the specified frequency) or if they indeed are some kind of synthesizer that generates the frequency printed on the package from some other crystal frequency.

    Of course it would be attractive for the manufacturer to do that, as they could manufacture a single device and then one-time-program it to the desired frequency, but frankly I find it hard to believe that manufacturers would do that without mentioning any of it in the datasheet or even the specsheet.

    They should know that not all users of the product can live with the disadvantages of having a synthesizer.

    A fixed divider, that would be another thing. But you would expect that mostly with low-frequency blocks specified for digital clock usage. E.g. a 1 MHz block could contain an 8 or 16 MHz crystal and a divider.

  • Hallo YO9HZN,


    do you have the CONNOR WINFIELD data sheet. You find it on digikey.com.
    What is your supplay Voltage? Nominal 3.3V Maximum 3.465V !
    The circuit connected to the Output (Pad5) shooud have an input capacitance of 15 pf.

    I hope you will realyse to have sucess with the TCXO.


    73 Hans-Jochen DK1MG

  • I tryed with 3.3V (measured 3.27V) pin from RPI 3 B, then Arduino Uno 3.3V pin. Same voltage, same result. Today I used a 117 linear LDO with 0.1uF decoupling caps (3.38V) . On pad 5 12pF to ground. Searched for optimal level using a CATV Amplifier (revers channels part of it , 5-50 MHz)... same results. Now I use the LNB with a TXC 25.000MHz 535NC 0041 txco. Works great , but it drifts +/- 5kHz at the 10706 beacon, dependent with the room temperature. Mail sent to ConWin. Waiting for the answer.

    73 Adrian , YO9HZN