This project was first published in Amateur Radio magazine volume 89 No.6 2021as a 250 watt unit only. It has since evolved, adding units for 500 watts and 1200 watts PEP to the range.These power ratings are programmed into the microprocessor using jumpers. The only other changes necessary are the number of turns on the toroids in the sensor heads, and 2 resistor voltage dividers provided on the main pcb.

  • Full Assembly Instructions for the project.

    Three photos and a PDF file showing alternative methods of constructing the sampling head

  • Standard kit construction using a plastic box
  • High power construction ( for 500 and 1200 watt versions) using a plastic box
  • High power construction using a diecast box to minimise signal leakage
  • A PDF file showing two different methods of wiring the sensor head


    This project is provided as a full kit of parts with everything supplied except the enclosure for the main pcb and LCD. This is not supplied because the main pcb and LCD can be assembled in at least three different ways, and it is believed that many amateurs may want to build these assemblies into existing enclosures.

    Kits are available for $50 plus freight. Write to me (Jim) at

    Payment can be made by either direct deposit to my bank account, or by me issuing you with a Paypal request for funds. I will send you these details and freight costs when you are ready to place your order :-).