CW Keyer by W7ZOI and W1FB



Schematic of keyer

This is a CW keyer that I built from a magazine article back in 1986. I have long since lost the magazine and the notes that I made at the time. I had no idea who designed this circuit until a couple of days ago, (August 7th, 2010) and how I made this discovery is worthy of note. Sometime last year I saw an advert on EBay for a CD containing a collection of, "Ham Radio," magazines in PDF format. The magazines ran from 1968 - 1990. The disc was cheap enough so I decided to buy it. When it was delivered I did open up a few of the PDF files and read a couple of the earlier magazines but other projects soon intervened and the disc was forgotten. One evening last week I had time on my hands after bashing away at this web page and I opened the PDF for January, 1990. To my surprise I came upon an article by Rick, K1BQT entitled, "TLC-Keyer." Looking at the schematic I realised that, although the circuit had been drawn differently to the way I was familiar with, this was indeed, the same keyer that I built back in 1986. At the end of the article was a note crediting the original design of the keyer to Wes, W7ZOI and Doug, W1FB.

I looked up Rick on QRZ.COM and obtained his E-Mail address and asked him if he remembered the keyer and the article and also if the accreditation was correct. He replied that he did remember the article and he was sure that he'd got the original design from, "Solid State Design for Radio Amateurs," published by the ARRL and that Wes and Doug were the original authors. He advised me to mail Wes to check. So I did. Wes very kindly replied promptly and did indeed confirm that the keyer was his design. So my search is over.

In operation the keyer is very simple. You plug a paddle or sideswiper into the stereo socket , switch the unit on and adjust the single control for speed and off you go! Press one side of the paddle for dits and the other side for dahs. Simple and easy to use and, more importantly at that time, inexpensive!

As I've stated on the drawing I made a minor modification to the original to allow me to use it with my Kenwood TS830S transceiver which uses a negative keying voltage. Needless to say, I hadn't taken that fact into consideration when I first tested the keyer. Three new NE 555 timers later and a cheap reed relay brought it back into operation relatively quickly! I also found that on certain bands RF would get into the circuit and cause problems with random dits being generated. I added some surplus 100nF capacitors between the stereo socket terminals and the case which cured that problem. I also gave it the ability to be powered by a 9V battery or by a 9V DC supply.

At the time I had two great friends who were also radio amateurs, both named John, G4VBF and G4WSK. Both are now "silent key," and very much missed. They liked this keyer so much that I was asked to make one for each of them. This I did and added a 10 second "tune-up" button to G4WSK's to enable him to load up his Yaesu FT101ZD without risk. That circuit used another cheap and common IC, the ubiquitous LM 741 op-amp. I built my keyer on a home made PCB but I may have used "Veroboard", copper-backed matrix board for the other two, I honestly can't remember now.

So that's the keyer, it's now approximately 23 years old and still sat here on the bench and still used. I'm glad that I can finally give credit to it's authors because, although it's not as "sexy" as an iambic keyer, in my opinion it has passed the most important tests of any electronic circuit. It is cheap, it is robust and it works.

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