KX3: Is it possible to double the Acc1 for doubling the CAT?

Discussion in 'QRP Corner' started by F6JJX, Dec 4, 2020.

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  1. F6JJX

    F6JJX Ham Member QRZ Page

    Hi All,

    I am using an Elecraft KX3 for not so long and it is time for me to get the most of it.

    My KX3 is connected to an Amplifier JUMA PA1000 that requires me to use the Acc1 plug (as data for band changes) and Acc2 for PTT. The issue i have is in that configuration i cannot use CAT control from the PC as the Acc1 is busy. Same if i want to emulate a waterfall with the I/Q as i will only get the audio and not the frequency (unless i am wrong).

    So in short, is it possible to double the Acc1? I naively tried to use a 3.5mm double jack (the one for headsphone) but it does not work.



  2. G7LTQ

    G7LTQ Ham Member QRZ Page

    have a look at https://sourceforge.net/projects/com0com/ and hup4com
    John N

  3. AG6QR

    AG6QR Premium Subscriber QRZ Page

    The serial data for ACC1 has three wires: a ground, a line to send serial data from a device into the KX3, and a line to receive serial data from the KX3.

    Two devices can't send data on the same serial line simultaneously (they might be able to share a serial line if they had some protocol for detecting/avoiding collisions, and making only one transmit at a time, but good luck with that). So you can't just split the entire ACC1 port.

    But multiple devices can receive data from a single serial line. This may be all you need.

    I have a Hardrock-50 amplifier that I use with my KX3. It receives CAT data from the KX3's ACC1 port to determine the KX3's frequency, so it can switch to the proper band filter. It does not send serial data to the KX3's ACC1 port. I made a cable to allow my KX3 to be connected to my amplifier and to a computer simultaneously. The computer is the only device wired up to transmit data to the KX3's ACC1 port, but both the computer and the amp receive serial data from the KX3's ACC1 port. This works very well, for logging, CAT control, transmitting serial data via CAT commands, and even updating firmware, all while the KX3 is connected to the amp, and the amp is automatically tracking the KX3's band selection.

    The cable has a 1/8" stereo plug that connects to the KX3's ACC1 port, and a 1/8" stereo jack that acts as a pass-through for the computer, with each wire from the plug connected to the corresponding wire of the jack. There is also a connector for the amp. The only connection between the amp and the ACC1 port is the ground and the line which receives data from the KX3.
  4. F6JJX

    F6JJX Ham Member QRZ Page

    Thanks John and Richard.

    I think that Richard nailed it, this is my issue exactly. I need to get the frequency data out of the Acc1 for both the CAT (pc applications such as N1MM or Panadapter) and the Amplifier (for band change).

    This is my data cable JUMA to KX3

    kx3 data.jpg

    I just need to find the one that carry the frequency data jack pin (tip or ring?) and find a way to wire this to the PC (USB?).
  5. DL2TM

    DL2TM XML Subscriber QRZ Page

    Directly not. elecraft using like the most manufactures RS232, the simpelst protocol I know. You can try it by an cheap USB-hub and USB-RS232-Stick for each device.
    Henry DL2TM

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