Sunday, March 22, 2015

DL4YHF Frequency counter re-package (Spring 2014)

I had an old QRP  transceiver that I wanted to start using.  I had modified it with a multi-turn  pot, which made adding a small counter one of my first projects.  Looking around I found the  4 - 5 digit counter by DL4YHF. 
This looked like it would do what I wanted.   It was small, had programmable IF offset, and used a readily available PIC micro controller.  The original used individual 7 segment LED displays.  I found some very small .36" 4 digit displays that would let me shrink the counter down to the size I wanted.  There are Hex code files available for either common cathode or common anode displays.  I built a breadboard version with only a small change to the input buffer, to get the sensitivity I needed. Information along with Hex code  is available at

I downloaded a copy of the free version of  Cadsoft's  EAGLE PCB software. After just a little playing around I was able to get a very small board designed, after I put a couple of surface mount capacitors on the bottom of the board.
Using 'toner transfer', I etched a circuit board, and built a working unit that fit in an Altoids tin .  After a show-and-tell at  the  monthly QRP club meeting, I had several people ask If they could get one of their own.   I ordered some boards from OSH  Park, and put together  kits for those who wanted them.  The artwork for the board is available for download in the Shared Projects area on the OSH Park web site.  
This is a single sided board and can very easily be made at home, or you can order a set of 3 from them for around $12.00.


  1. I need PCB Bottom layout

  2. only thing on bottom of board are the two 33pf
    SMD capacitors. either 1206 or 805 size should work

    Eagle file is at