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Class E CW, again...




 
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Author Topic: Class E CW, again...  (Read 2052 times)
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ka1tdq
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I make stuff


« on: November 28, 2020, 08:00:24 AM »

This topic has been visited many times and the discussion has centered on reducing key clicks from the square waves generated during class E amplification. I built something a while back using a large inductor to smooth the edges of the drain supply, but never tested it. Thinking back now I believe even that was too complicated. Wouldn't something like this work?

Leave the gate drive on all the time and just key the drain voltage through a solid state relay block and a huge inductor. Forgive me for reducing everything to spark gap simplicity, but I don't think it needs to be any more complicated than this.

Jon


* IMG_0066.jpg (2879.61 KB, 4031x3023 - viewed 265 times.)
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vk3alk
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« Reply #1 on: December 01, 2020, 05:09:18 AM »

Hi Jon....

I have absolutely no idea what I'm talking about here but this youtube clip might give you some thoughts anyway....

https://www.youtube.com/watch?v=n6JHSSUBTME

Although very low power you maybe able to introduce ideas to your CW Class E ..... maybe not  Huh


Wayne
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km6sn
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« Reply #2 on: December 01, 2020, 08:45:51 PM »

LTSpice simulations of the keying circuit shown in the youtube video look pretty good.
See attached pix. These waveforms are taken at the top of the 28 ohm resistor.
Both rise and fall time are in the vicinity of 2ms; probably no clicks from that timing.


* rise.png (34.82 KB, 1280x1000 - viewed 219 times.)

* fall.png (35 KB, 1280x1000 - viewed 211 times.)

* keying-ckt.png (48.28 KB, 1280x1000 - viewed 237 times.)
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km6sn
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« Reply #3 on: December 01, 2020, 09:14:51 PM »

Attached is the full waveform; see file full.png

The LTC spice file is attached as keying.txt; change the file extension to .asc for use with LTC spice.

By the way, EVERY ham should learn LTC Spice modeling. It is invaluable, and if you have patience
you can learn it. Check youtube for videos.


* full.png (36.34 KB, 1280x1000 - viewed 228 times.)
* keying.txt (1.26 KB - downloaded 109 times.)
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