CW Decoder to Improve Your Fist

I’m often told that I have a good fist but I’m aware I have a tendency to run together some words and letters.  I figured that watching a transmit decoder would help me improve.  Unfortunately, my current rigs don’t have this feature.

Also, since I’ve been trying to learn to use a straight key, a decoder that I could watch while sending should help with that, too.  Sloppy letters or missing spaces would be made visible.

I’ve made Arduino decoders over the years but for simplicity, I settled on one of the ubiquitous Chinese decoders offered on eBay and Amazon for $20 or so (they used to be $10, but so it goes).  Actually, I got mine on Amazon as “used,” probably because it had been returned.  These decoders are notorious for poor decoding from a receiver’s audio and thus get lousy reviews.  However, with direct input from a key or external keyer they do well.

Note: For some reason, this site isn't letting me position photos within the text today. See images at bottom.

The decoder has a key input and connecting a straight directly to it works well.  So does an external keyer if it has a relay output.   But the decoder’s input is at 5v and 10K ohm when open, thus puts transceivers into transmit when connected directly.  So one can’t connect the decoder directly to the key and the transmitter input at the same time without some way of isolating the decoder from the transmitter.

I asked Chatgbt for a solution and it suggested an optocoupler circuit.  When I looked carefully at the circuit, though, I realized it wouldn’t work.  I told Chatgbt so, and it agreed, then sent me on some other rabbit trails.   I ended up ignoring them and simply isolating the decoder with a 1N5711 Schottky diode.  The key is connected to the transceiver as usual, and the diode is in the positive line to the decoder key input.

The decoder runs nicely on a 9v battery but I wanted it to turn on along with my other gear, so I powered it from the switched 13.8v DC line that powers my equipment.   I put three silicone diodes in series with the positive DC line to limit the voltage to the decoder.

Two key jacks wired in parallel on the back, connected to the decode key input through the diode, accommodate the external keyer and the transceiver.  A barrel connector on the back supplies power.

A case isn’t really needed but I found an old project box and rather than cut out for the display, used a piece of acrylic for the cover.

It is an easy and inexpensive project and works very well for me.  I recommend it to anyone trying to learn or improve their CW.

There are a variety of Chinese decoders out there, most of which are pretty similar.  Here is a manual that may be helpful.  Since this application is not using the audio inputs, the main thing to know is that the red button turns on and off spacing between words.

Note:  Earlier, before trying the diode approach, I made a decoder  using a 5v relay and powered by a 9v battery.   It works well, too, but does have audible clicks.   For that one, I mounted the whole decoder unit on the outside of the project box.

The decoder I used

Earlier version mounted on outside of box, powered by 9v battery