An idea for a modular antenna tuner system

Discussion in 'Homebrew and Kit Projects' started by KW4TI, Jun 8, 2018.

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  1. KW4TI

    KW4TI Ham Member QRZ Page

    I am working on some ideas for a modular antenna tuner system that I can use to explore some ideas I have on how to improve antenna tuner units. Basically, the idea is that the tuning system consists of these single PCB units that can be configured to be selectable series inductors or parallel capacitors just by soldering in jumpers and then soldering in the capacitors or inductors to be selected in the appropriate places. There are also two output ports on each section that are selectable so that each of the sections can be switched, for example, between being a shunt or series element depending on which port is selected, or for example an L network can be switched from being a high-Z to a low-Z network. Here is a thumbnail of the PCB I designed.


    The PCBs are wired together and then a master controller send commands to the the relays using the I2C bus. So these boards would be wired together with their ports tied together in various configurations, and the actual configuration of the tuner selected by switching which of the two ports of each section the output is on, so for example one could swap capacitive and inductive sections just by configuring the relays.

    This is the controller which is based on a Atmega328p arduino compatible board. It has a tandem coupler with a special design for measuring the impedance of the load. There is also a serial port for programming the microcontroller. I would like to use this is as a remote tuning unit and so I also can attach a HC-12 wireless serial unit and send commands over the 433 MHz ISM band, and this unit has a bias-tee so that it can be powered over the coax. There are seven ports on the board for up to seven controllable tuner sections. I may use a I2C display if it is not used remotely which would be plugged into one of the ports.


    I have the schematics to what I have designed below which I think could be of interest.


    Attached Files:

    OE2RPL and VK4HAT like this.

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