HACKRF as half duplex transceiver for qo100 and hF, how to?

  • I would like to ask for a recommendation how to connect hackrf to antenna and use amplifier for transmit.

    I want to use 2 different amplifiers one for 2-30mhz and one for 2400mhz. I will switch them manually base on need.
    (2-30Mhz)3W https://rb.gy/sgfens
    (1-3Ghz )1W 5v usb https://rb.gy/r0pqsa

    But I have a problem with receive part, since amplifier drop out all my receiving signal to 0 [like band stop filter for receive].

    I have think about to to modify pluto firmware to add PTT functionality to GPIO pin.
    Theoretically modification of firmware (/libhackrf/src/gpio.c).
    If this would be valid, I would have some power indicator when I am transmitting and use it.


    As shown on the picture: Transmit path use TX magenta and for receive RX should use green path.
    There should be now interconnection between tx an rx. (I want not to burn out RX part).
    I guess PTT can be used as a trigger for change of active tx/rx path.

    Would it be possible to use some relay or something for switching rx and tx for same antenna?

    Would you recommend how and where to connect TX power when I am receiving.
    [I am not sure what would be delay with TX amplifier, when I switch it power on -> if it would be in mili sec or sec]
    It is my constrain regards using relay to power on off amplifier.
    I can not connect PA to ground or keep it empty, since I guess I would risk a damage of PA.

    I want to use PA with power amplification < 5w for digital mode ft-8/4.
    And use same antenna for RX an TX path.

    I would like to avoid to have 2 devices like:
    one hackrf for transmit only and one
    sdr stick for receive.

    Hack rf is nice device with good sample rate.
    Adalm pluto is not an option, since it will not work on 0-30mhz.

    If you have just an any idea, how to connect it or manage it, please give an hint.
    I am a newbie in that field and do not want to damage my device.

    Thx a lot George(J).

    Ps: ? Maybe dummy load for TX