Posts by DL3DCW

    PTT output modification Allnet ALL3075v3





    This modification allows control main power (SUPPLY) and PTT (AMPLIFIER) independent with only one device

    I use two Ubiqiti NanoStationM5 (5GHz) for the WLAN-Link (50m) to the Pluto. It works fine and stable without any problems (DATV).


    To switch on/off complete Pluto equipment (power supply, PA etc.) i use Allnet ALL3075v3 which is connected to te second LAN port of the NanoStationM5. So you dont need a seperate network switch.


    Additionally i have connected the yellow LED of the Allnet device via optocoupler to PTT input of the PA. So i can control power and PTT with only one device.

    Pi3+B

    Ohh, then you use the very old image "satcontrol_02.img.zip" ... :/


    The actual image with a lot of improvements is "satcontrol_06.img.zip". It requires a Raspberry Pi 4B.


    I recommend to use only the last actual image because the differences are too big. There are also significant changes in the user interface.

    For the the menu you only have to press the "Set" button. Then all menu items will be show. This is new in the last versions so you don't need to click right mouse button)


    A1: To adjust master signal press "Lock". Then GQRX automatically tunes to 10.706,000 MHz (-1,5 kHz).

    A2: The engineering beacon is on 10.706,000 MHz (default setting, see screenshot in my last posting).
    A3: After adjusting audio signal of the beacon to 1,5 kHz press "OK" (also see the same screenshot).


    Simple procedure:


    1. Press "Set"

    2. Press "Lock"

    3. Adjust engineering beacon signal with mouse wheel to 1,5 kHz in audio spectrum

    4. Press "OK"

    5. Switch on "Drift correction"


    Then in the ERR field you see the actual drift. After "Lock" procedure it starts at 0 Hz. Thats all.


    NOTE: You need 2 SDR-Sticks. One for GQRX and one for the master signal (drift correction).

    Hi Stefan,


    thanks for response. Some things should be noted before operation:


    1. Lock to master signal


    First, the system must be set to a reference signal (menu item "Lock" ). This is used to calculate the actual LO frequency and as master signal for the software drift correction. Default setting is the engineering beacon of Es'hail-2 (menu item "Master"). With the preset RF frequency you have to adjust the peak in the audio spectrum to 1.5 kHz.



    This process must be repeated occasionally if the LO frequency has drifted too far away. If you have problems, you should experiment with the parameters and possibly restart the program (unfortunately this function is not perfect at the moment).


    2. Adjust beacon frequency


    Fast fine adjustment is possible with a beacon signal in NB passband (button "Adjust"). Default setting is the middle beacon of QO-100 transponder (menu item "Beacon"). With the preset RF frequency you have to adjust the center of the signal in the audio spectrum to 1.5 kHz.


    This procedure should be performed before each operation (after a short warm-up phase). Because the SDR software sometimes shows errors of some 100Hz. This often happens when you restart GQRX, change frequency ranges or if you tune via the big frequency indication digits. For tuning it will be better to use the mouse wheel and/or place mouse pointer to desired frequency in the waterfall. The fine adjustment should be checked regularly. In the future hopefully this step can be omitted.


    At which step do you have problems?


    Frank, DL3DCW

    The housing is based on aluminum profiles from eNUC-SB1 case. The front and back panels are custom-made. Also the mounting plate so that no drilling is required. I also plan to make circuit boards for the main board (with USB converter etc. placed on top of UpCon6W) and LED mounting.


    If there is enough interest, I will consider preparing some kits. But due to probably small quantities, unfortunally it will not be a "low cost" housing ;-)

    Very nice project. I have some questions:

    TRV in one box has a receiving part (740MHz)

    Is the receiving part (740MHz) feeded trough or is it converted to 29/144/439MHz?

    It injects a stable 25Mz signal into the LNB and is powered by 12V.

    Do you have any experience with frequency drift depending on heating from sun and/or internal power amplifier? Because the 0.5ppm TCXO is build in and the transverter should be mounted outdoor (to avoid cable loss because tx power is max 2W).

    There is no special autostart function for GQRX added in the image.


    Also there is no root password set because it is not needed for normal operation. For SSH you only have to enable SSH under "Preferences/Raspberry Pi Configuration/Interfaces". Password is default (pi/satcontrol). You also can enable VNC in the same way.

    I want to built portable a station with as less components as possible. Second I wanted to know if someone already had the same idea?

    I think the best compromise will probably be to replace the GPSDO with a TCXO. It is simple, cheap and stable. At least the TCXO is not exposed to high temperature fluctuations. So do not position the TCXO in, on or near the PA ;-)


    The tx chain of my own simple station is also stabilized "only" by a TCXO. I am happy with that.