Posts by DD1US


    well, we have to acknowledge that not all radio amateurs are able to actively contribute to science and society. This may be due to a lack of technical knowledge or a lack of free time besides the daytime job.

    For such people there is still the option to support organizations like AMSAT by money (by membership fees or by donations) and thus enable those organizations to forster contributions to science and society.

    But for sure there are also quite some, who do not contribute anything but only benefit from the knowhow, time and money others are spending. As long as they value what they are enjoying it is fine for me but those who are only complaining without contributing are a real PITA.

    Kind regards



    A SDR based system must use the capabilities of software based solutions in order to do things that can not be done or is very complicated to do with hardware. All of us try to replicate hardware solutions into the software solutions and not think what new features can be implemented.

    Good point George, but you still have to be compliant with the regulations in your country and according to your license.



    Hello Gerhard,ok.

    I think if you transmit with low power then that might be feasible with a Pluto. I wish you good luck and make sure you are measuring your emissions at a dummy load before transmitting with an antenna.

    Kind regards


    Sehr schön Armin,

    vielen Dank für die interessante Beschreibung!

    Falls jemand der Leser die Anleitung als pdf Datei haben möchte, um sie zu speichern oder auszudrucken,

    dann kann er mich gerne anschreiben. Ich habe die Webseite von Hand in ein Word- und dann pdf Dokument konvertiert
    und werde sie euch gerne zusenden (es muss sich ja nicht jeder die gleiche Arbeit machen).

    Viele Grüße


    Hi Detlef,

    really, are you sure ?

    I think everybody should think about whether he wants to buy from someone who is ignoring clear rules of the satellite operator and
    even makes money selling such non compliant components.

    For me I have made my decision.



    Hello Pedro,

    the Pluto will most likely not work properly with a 10 MHz reference. A friend tested 4 or 5 Plutos and only one of them worked properly with reference frequencies of 20 Mhz and below. Therefore it is advised to use reference frequencies higher than 20 MHz, 40 MHz or even 50 MHz is strongly recommended.

    If you generate your reference by using frequency doublers e.g. 40 MHz out of 10 MHz you will loose the same amount of phase noise performance as running the PLL with a lower reference frequency. Of course this is only true if the doubler is ideal and also the PLL.

    In a latest design Kurt DJ0ABR has developed a simple unit using a 100MHz OCXO and 2 dividers :2. With this we generate 50 MHz for the Pluto and 25 MHz for the reference frequency of the LNB. Simple and very good. The circuit of Kurt allows also to lock the OCXO additionally to a GPSDO. I have buil this up and it works very fine. The GPSDO is not really needed as the OCXO is very stable.

    Kind regards


    Hello Alfred,

    very nice.

    I have also built such a Reference Clock and Distribution Unit based on the development of Kurt DJ0ABR and it works really great.

    It simplifies the setup especially with the Pluto tremendously: the unit from Kurt, the AMSAT-DL 46dB PA, the Pluto and a modified LNB attached to a POTY-Feed in a 60cm dish and we have a perfect full duplex QO-100 setup.

    Kind regards


    Hi George,

    I am also not sure whether I understood what Johan wants to accomplish. So we need his response.

    In any case I think there are 2 "links" where multiple signals can be combined.

    1.) One is the receive path as I had described above,

    2.) The other is the path from the transverter to the transceiver where the RX-IF-signal, the TX-IF-signal and the reference signal can be combined. For the second topic I am using a triplexer from Diamond.

    You can find a description of ma portable setup (where both "links" are using multiplexing) here:…0English%202020-09-26.pdf

    Kind regards



    many people are using the cable from the LNB to the receiver to send 3 "signals" over the single cable:

    - the receive IF signal e.g. 740 MHz

    - the supply voltage for the LNB including the information to switch between V and H polarization (14v / 18V)

    - the reference frequency signal for the LNB (typ. 24, 25 or 27 MHz)

    Sending the local oscillator signal for the LNB upstream will be very difficult as it is a rather high frequency
    and the attenuation of the cable will be very high.

    Triplexers for the above mentioned 3 signals are built into the AMSAT-DL downconverters and can be bought
    stand alone for instance in the BATC shop in UK (design by Mike Willis G0MJW). Here is a descrition of my built:…from%20G0MJW%20rev1.2.pdf

    Kind regards


    Hello Martin,

    looking at the manual of the QO-100 Groudstation of DX-Patrol indeed it shows that the transverter is working only simplex.

    AMSAT-DL has made very clear for a long time than full duplex operations is requested by users who want to use QO-100.

    DX-Patrol is making money by leveraging the investment others have made by implementing the QO-100 ham radio satellite
    and they should respect the rules given by the operator of QO-100. Yet it looks like they are simply ignoring it.

    I think this is very disappointing!

    We can already today see the problems many people, who are using simplex operations, have to demonstrate proper operation.
    They talk over each other frequently without noticing. In pileups it is quite easy to distinguish those with a proper full-duplex setup
    and good operating skills from the others.

    Hopefully many radio amateurs will understand that this transverter is not compliant to the requested operation mode on QO-100
    and will thus choose one of the many other better solutions.

    Kind regards