KK1L tower tri-bander 40m dipole DXE-3x10 skyhawk

KK1L Antenna Switching

Introduction
Designed primarily for the HF contester the antenna switching system will easily allow two radios to be connected to any of six (or 8) antenna feeds without allowing either radio to transmit into the other. The focus is on having a very flexible Single Operator Two Radio (SO2R) setup you can build yourself.

I have designed the switches with high RF integrity in mind to provide a hard to find DIY component for you to design around.

At its most basic there are two parts to the project…

  1. The relay board and enclosure, which could be mounted at the base of the tower or elsewhere
  2. The control circuitry and enclosure. This can take the form of the WiFi controlled “FreqEZ” from K8UT, the controller board I designed, or simply using a rotary switch. There is nothing stopping you from rolling your own controller for just your situation

It can be possible to house both the control and relay board in the same chassis…the 2×6 and 2×8 boards are designed to support this with a Rasberry Pi Zero W and FreqEZ combination. Or you can roll your own Raspberry Pi or Microcontroller based decoder and controller, or use the options I provide. Go for it! Jump in and have fun.

22-DEC-25: K8UT FreqEZ HATs now available!

  • 2×6 Relay Board
  • Dual Controller / Band Decoder
  • 2×8 Relay Board
  • FreqEZ HAT16
  • FreqEZ HAT8
  • Raspberry Pi Zero W for FreqEZ HAT control

I’ve gotta build me one!

  • Connect 2 radios to any of 6 or 8 antennas or more
  • Combine multiple boards to incorporate bandpass filtering
  • Designed for up to 30MHz operation…6m with reduced performance
  • Leading edge using K8UT’s “FreqEZ” with a Raspberry Pi ZeroW to add full wireless control!!
  • …or go “Old School” and use the Dual Band Decoder / Controller
  • …or go “Cave Man” and wire direct from a rotary switch
  • …or roll your own and design a controller from scratch
  • Cobble up or 3D print a chassis (does not have to be RF tight)
  • Use parts from your junk box…the design uses through-hole technology
  • Supplement from a full “Project File” parts list at Mouser.com
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