LNB downstream and LO upstream over 1 coax

    I saw at homebrew solution at ON4CJQ running both signals over 1 coax to the LNB.


    Has anyone done this also?


    I am working on my own implementation of this so that I can reduce the cabling to the LNB head.

    But before launching pcb production just want to check if it exists already.


    Johan

    ON4IQ

    Hi,


    Can you provide the link of the ON4CJQ solution? Also keep us informed about your progress. I use 25 MHz+740+bias and 430 for the other cable. I run about 60 meters. A Lab testing can be personal run from September. Also I use a second cable for H. Maybe a combiner can be used also to use a single cable for NB and WB signals. One question to the designers of QO100 is why NB and WB use different polarization?

    Johan,


    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:


    http://www.dd1us.de/Downloads/…from%20G0MJW%20rev1.2.pdf


    Kind regards


    Matthias


    http://www.dd1us.de

    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:


    http://www.dd1us.de/Downloads/…0English%202020-09-26.pdf


    Kind regards


    Matthias


    http://www.dd1us.de