PICAXE-28X1 BXF Shack Controller (SO3R / SOMR)

This project is for a PIC based audio and PTT controller which has a single headset and foot-switch which can connect to 3 different ham radios at once for a single operator to simultaneously receive or transmit on any combination of the radios.


I’ve been working on this project for a while.  I like to monitor more than one radio at a time but found it annoying having multiple speakers.  Also for transmitting I didn’t like the fact I had to have multiple mics and foot switches…
So I decided to make a shack controller which allowed me to connect a single headset and foot switch to 3 radios with the option to choose which radio I would receive on and transmit on.
Some more info on SO2R (single operator 2 radios) and SOMR (single operator multiple radios) can be found on Wikipedia: http://en.wikipedia.org/wiki/Single_operator_two_radios although this controller interfaces with 3 radios.

The switches are based on the CD4066 quad analogue switch device which is controlled from the PIXACE-28X1.  The 3 green buttons switch the received audio in and out and the 3 red button the TX and PTT.  The code is written as such that the red buttons, i.e. enable TX, also enables the RX on that band when enabled and disables RX when TX is disabled.  Even when the shack controller is on PTT it’s possible to add and remove bands from RX or TX.
There is a speaker output on the back which is muted when the headphones are plugged into the front.
Something which is not shown in this revision, and I’ll update later, is the addition of isolation components between the radios and the controller.  This is made up of an audio isolation transformer on both the mic out and speaker in audio lines, and an opto-isolator for the PTT instead of the transistors.

I’ve updated the code in early June 2011 to v1.4 so that if a TX button is held in for 0.5 seconds or is held when the PTT is pressed then it switches all the channels off except that one.  This is useful if all 3 channels are being monitored and the situation calls for only one channel to be used.  Think CQ calling on all 3 channels and wanting to only answer on one, instead of pressing 2 buttons (to disable those channels) you now only need to hold the button on the channel you want to reply on.


 BXF_Shack_Controller_v1.4_Page1 BXF_Shack_Controller_v1.4_Page2

PCB Layout


Project Files

Click on the links to download the file.

ExpressSCH v1.4 Schematic

ExpressPCB v1.4 PCB Layout

PICAXE v1.4 Code

Project Pictures


SOMR In Action


  1. Conrad

    Hi Gavin this is just the kind of thing that I’m looking for. Do you know if David has progressed this?

    73 Conrad G0RUZ

    1. m1bxf (Post author)

      Hi Conrad,

      Unfortunately not, Dave has had no time, or direction from me to be honest, to do any further work on it. I’ve not chased him because the unit I’ve made works so well in contests and on DX’Peditions.

      Gav, BXF.

  2. Keith

    Hi Gavin

    Your ExpressPCB v1.4 PCB Layout link is not working I am still looking to build a copy so your PCB layout would be useful or are PCB’s available.

    Is your 4m amp control unit info available or was it a commercial unit?

    73 Keith GU6EFB

    PS now the rig has been repaired should be able to work you again in the contest

  3. Anthony G7LRQ

    Was wondering if you have one of the PCB for the PICAXE-28X1 BXF Shack Controller (SO3R / SOMR) spare that you could sell me, I can do everything except make the PCB and this will solve my three radio problem.

    Regards Anthony

  4. Keith

    Hi Gavin

    Thanks for a great website
    I am very interested in your shack controller and was wondering if PCB’s were available or if not did you have the PCB art work to allow us to make a PCB?
    73 Keith GU6EFB

    1. m1bxf (Post author)

      Hi Keith,

      I did reply direct to you a while back on this, I’ll try and dig out my email for you. For now I’ve fixed the broken URL to the PCB file. I’ve none available due to the cost of making small quantities, but it’s not too hard to make your own, although it is double sided a bit more care is needed than usual.

      There is still the ongoing updated version being created by David M0GUM but nothing is complete or published yet, I’ll get an updated status as his design was intended to become a kit.

      Look forward to hearing you again on VHF!


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