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Full Duplex satellite work on 6400

Eric_M0REQ Member ✭✭
Hi I am trying to work QO-100 via transverters with I/Fs of 28/28 or 28/50 i.e tx and rx on 28Mhz or rx on 28 and tx on 50Mhz. when i tx i lose the signal in the waterfall.

I am using two separate transverters for tx and rx so i don't expect one to swamp the other.

i appreciate i only have one SCU but if i am using the same freq for tx and rx it should work shouldn't it?


  • VE7ATJ_Don
    VE7ATJ_Don Member ✭✭✭

    HI Eric.. I'm not exactly sure why you need the transverters, since the 6400 will already 'rx on 28' and 'tx on 50' without the use of transverters -- you just need to set up 2 panadapters -- on 10m and the other on 6, and make sure the TX button on the flag on 6m is turned on (red).

    But, in any case, according to the SmartSCR manual, section 32, '..When FDX is enabled, the transmitting Slice Receiver is muted, along with all other Slice Receivers on the same antenna. Receivers located on different antennas [sic] from the transmitter are not muted during transmission.'

    Does this help? Maybe you need to move or set up a separate receiver antenna?

  • Al K0VM
    Al K0VM Member ✭✭✭

    If you're seeing the TX in the panadapter but not the WF, then you may need to activate FDX and 'Show TX in Waterfall'.

    I assume you're using a slice with RXA port for rx connected to the RX transverter, and another slice with XVTR port for tx connected to your TX transverter.

    You should see your TX in the TX slice PA and WF. Seeing your TX in the RX slice would depend on the signal into/from QO-100.

    AL, K0VM

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Eric, I think that you just need a Diplexer (Duplexer?). Not sure that I really understand the difference... In any event, that should let you connect both transverters at the same time and use FDX to hear the downlink while transmitting. I think that Mike, VA3MW has a writeup or a diagram of that somewhere.

  • Eric_M0REQ
    Eric_M0REQ Member ✭✭
    Thanks guys, the satellite re-transmits my upload signal transverted to 2.4 GHz back down at 10Ghz so I should be able to see my own signal in the RX waterfall but the RX waterfall goes blank when I tx.
  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Eric, if both transverters are on the same IF, you won't be able to use Full Duplex. If you have one on a 28 MHz IF and the other on a 50 MHz IF, then Full Duplex should work. This would require a diplexer, as mentioned above.

  • John KB4DU
    John KB4DU Member ✭✭✭✭

    General ham convention for a duplexer is allowing tx and rx in the same band. Diplexer allows tx and rx on separate bands.

  • Eric_M0REQ
    Eric_M0REQ Member ✭✭
    Ok thanks, I won’t need a duplexer as I only tx on one band and RX on the other for QO-100. A duplexer is required for LEO satellites as you might need to tx and RX on either band depending on the sat config.

    I think the comment the both panadapters share the RECV port might be the issue if that is muted on tx. I am not sure I am able to configure another RX antenna or no antenna for the tx panadapters.
  • K3SF
    K3SF Member ✭✭✭

    The 6400 can not do full duplex like you want....you only have one scu...

    Paul K3SF

  • Neil D Friedman N3DF
    Neil D Friedman N3DF Member ✭✭✭✭

    Manual says 6400 can do full duplex, including satellite operations, with adequate antenna isolation and external band pass filtering. Use RXA and XVTA ports.

  • K9YK
    K9YK Member ✭✭

    Due to the TX/RX signal routing on the 6400, the ONLY way it can do full duplex is to TX out the ANT1 or ANT2 connector and receive via the RXA connector on different bands. It can NOT TX via the XVTA jack while it is receiving via any other antenna connector.

    I have a pair of Q5 transverters, one with a 14Mhz IF and the other with a 50Mhz IF. I’ve tested all this out, and it’s just not possible unless your transverter is capable of 5-10 watts input on the TX IF connection. My 6400 is headed back to Austin and I have a new 6600 waiting in the manufacturing queue.

  • reed
    reed Member ✭✭

    To elaborate on K9YK's explanation, in the 6400 hardware manual, chapter 12, there's a nice diagram showing the antenna connetion points and routing: https://www.flexradio.com/documentation/flex-6400-and-flex-6600-hardware-reference-manual-pdf/

    Transmitting on either ANT1 (red) or ANT2 (orange) while receiving on either RXA (purple) or XVTR-A (blue) should work, as they do not cross paths:

    However, transmitting on the XVTR-A blocks the path that SCU0/ADC wants to take:

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