Mid 1970’s iambic keyer CMOS DIY design - Page 1
Forum section: electronics / rf-microwave

author: Kjo
author_rank: Regular Contributor
timestamp: December 17, 2021, 02:22:26 am
content: I built a keyer in ~1976 based on 9 4000 series ICs and a few capacitors and pots. 45 years later, I still have it and it works sort of. Dots work but dash no. It was built on a perf board with wire wrap. I will never figure it out with that construction. But I remember that several of us at Hughes Aircraft built this from plans in QST, or Radio Electronics or some other magazine of the early 1970’s.I’m hoping there is someone out there who is as old as me and remembers this project. I’d like to fix this thing and use it. I know that there are many micro based designs that are better, but there is the nostalgia thing.Kjo - KO3Y

author: Kjo
author_rank: Regular Contributor
timestamp: December 17, 2021, 02:28:00 am
content: I have looked for this in the past with no luck, but I now found a reference to a QRP Accu-keyer. This may be it!

author: mag_therm
author_rank: Frequent Contributor
timestamp: December 17, 2021, 02:51:26 am
content: Here is one projectIt is paywalled : (Australia Trolley == USA Cart)-----------------------------------------------------------------------------------https://www.siliconchip.com.au/Shop/15Electronics Australia article scan, March 1978 - Electronic Morse Code KeyerScan of the Electronic Morse Code Keyer article from Electronics Australia magazine, March 1978 issue.7 pages, 11.3MB.There is a copyright notice watermark on each page.Cat No SC3080. Price: AUD $10.00 1 add Add to trolley

author: floobydust
author_rank: Super Contributor
timestamp: December 17, 2021, 03:12:10 am
content: 73 Magazine CW Keycoder IJuly 1976, improvements 1977 Aug.pg.159Electronics Australia March 1978 oops it has paddlesedit: deleted url so not to spoil it

author: Kjo
author_rank: Regular Contributor
timestamp: December 18, 2021, 01:53:39 am
content: Thanks for the suggestions, but it was indeed based on the Accu-Keyer in QST August 1973. I evidently took liberal freedom back then to apply DeMorgans theorem. But I fixed it!QRP_Accu-Keyer.pdf(1004.72 kB - downloaded 200 times.)QST_Aug_1973_p19-23.pdf(989.43 kB - downloaded 337 times.)Actually the TTL was from QST and the CMOS version I built was from Aug 1975 73 mag.73 mag article has no detailed functional description, but the QST article does.And K7MEM did a analysis that is quite good.https://k7mem.com/Keyer_Accu-Keyer.html

author: wn1fju
author_rank: Frequent Contributor
timestamp: December 18, 2021, 01:47:04 pm
content: I built a similar keyer while I was a poor, starving grad student, sometime between 1975 and 1979. I don't remember where I got the schematic, but it had to be either from QST or the Radio Amateur's Handbook.I had nothing in the way of tools or expertise. The construction was done on perf-board with point-to-point wiring (mostly with bare wires!!!). This was a memory keyer and used an Intersil IM6518 1024x1 SRAM. If I recall, the memory IC cost more than all of the other parts combined. It was originally battery powered, but at some point I added a jack on the back panel for an external DC power supply. It had a sidetone oscillator, an internal speaker, and a +/- key output polarity switch, although I may have added some of those features later.I haven't used the thing in decades, but I just powered it up and it works fine. It was always a bit annoying to use the memory function, however. You flick the run/load switch to load, send your message, then flick it back to run and the message will play out whenever you hit the red button. But there was no provision to stop the loading of the 1024 bits, so after you keyed in something to load, you had to wait until the chip loaded itself with "blanks" until it reached the end. And you had better key your characters in with perfect timing. It usually took a few tries.

author: Kjo
author_rank: Regular Contributor
timestamp: December 19, 2021, 07:57:50 pm
content: Quote from: wn1fju on December 18, 2021, 01:47:04 pmNice assembly!Back in 1975 I wasn't so good at construction techniques. But if all the wirewrap connections hold up it still works!

author: Kjo
author_rank: Regular Contributor
timestamp: December 21, 2021, 11:20:53 pm
content: Shamed into putting the keyer in a real box!

author: wn1fju
author_rank: Frequent Contributor
timestamp: December 22, 2021, 01:50:15 pm
content: Nice job! I guess these things are for nostalgia nowadays. Almost every modern transceiver includes a built-in keyer. But it fun to reminisce.

author: Kjo
author_rank: Regular Contributor
timestamp: January 28, 2022, 04:25:14 pm
content: @wn1fjuYea, that is true, as my uBitX has one too. But adjusting is more hassle than the dedicated keyer. But nostalgia is the real reason. I still have the 1975 dual paddle home made key as well!Ko3y