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Author Topic: A Tunnel Diode Keyer (at last!)  (Read 1081 times)

Offline AA1TJ

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A Tunnel Diode Keyer (at last!)
« on: December 08, 2013, 16:48:18 UTC »
Hi Folks,

I've had an idea that it might be possible to build an electronic Morse keyer using tunnel-diodes since I first read about them as a kid. Several early attempts were unsatisfactory, to say the least. Fast-forward forty years: While taking a shower last month a design possibility popped into my head "out of the blue." Unlike most of my "brilliant" ideas this one actually worked on the breadboard ;-)   

I'm using the classic, W9TO keyer configuration in which an astable multivibrator is followed by a pair of bistable flip-flops (FFs) connected in series. The combined (OR'd) FF outputs comprise the dashes. In my circuit a tunnel-diode relaxation oscillator feeds a pair of tunnel-diode bistable FFs. My recent revelation involves gating the FFs with biased signal diodes. The attached oscilloscope screen-capture shows the DOT/DASH output waveforms.

I made the first QSOs on 20m the other day with my new keyer. While it has no "bells and whistles" (no dot/dash memories, iambic operation, etc.) it does send very tolerable CW. I realize that an electronic keyer made from five Soviet-made tunnel diodes is "small potatoes" in a day of full-functioned keyers on a chip, but for me it was a childhood dream finally come true. I'm presently working on a magazine construction article, but for now I just wanted to share my news.

Happy Holidays,
Mike, AA1TJ

Offline IZ5ZCO

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Re: A Tunnel Diode Keyer (at last!)
« Reply #1 on: December 08, 2013, 17:02:09 UTC »
Many thanks, Mike, for your sharing!

72 de
Nicola
72 de Nicola

Offline AA1TJ

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Re: A Tunnel Diode Keyer (at last!)
« Reply #2 on: December 08, 2013, 18:17:37 UTC »
Prego, Nicola...you're very welcome.

Ciao,
Mike, AA1TJ

Offline AA2JZ

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Re: A Tunnel Diode Keyer (at last!)
« Reply #3 on: December 08, 2013, 23:40:00 UTC »
Have you a schematic ? Sounds interesting,and I would like to build the circuit just for the fun of it.

Carl  AA2JZ
Carl, AA2JZ
Solder fumes are GOOD for you.

Offline LU6DO

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Re: A Tunnel Diode Keyer (at last!)
« Reply #4 on: December 09, 2013, 05:17:43 UTC »
Good contribution Mike. Many tnx!
La radio es maravillosa, pero, siempre recuerda que lo más importante en la vida son los afectos y las vivencias.

Offline PG4I

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Re: A Tunnel Diode Keyer (at last!)
« Reply #5 on: January 09, 2014, 07:05:21 UTC »
Interesting idea Mike, thanks for sharing! Looking forward to read the article.
Joop - PG4I/QRP

Offline ve3lyx

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Re: A Tunnel Diode Keyer (at last!)
« Reply #6 on: February 05, 2014, 18:39:49 UTC »
cool deal. When comes the schematic? Pattern looks good!
Don