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Author Topic: GOODBYE CLASS "E": WELCOME CLASS D REVERSE "1/D"  (Read 18843 times)
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Posts: 175

« Reply #25 on: July 19, 2022, 05:55:21 PM »

I'm up for that yes please PM me and I'll provide details.
I'd rather pay something, even do a swap or something..?

The sine drive I described was for single ended (15W@12V).

The other versions are push pull, one using an AD9833 driving a dual invertor to square and inv square for both phases and the other design just uses the direct o/p's from an AD9850. Both give around 40-42% duty cycle.
 Altho I'm unable to adj the duty cycle or phase  both designs seem efficient enough and are very simple build.

When I first did my experiments and simulations some 15 years ago small variations in the duty cycle just seemed to alter the tuning and then I retuned to restore the peak efficiency.

Let keep it going on!


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« Reply #26 on: July 20, 2022, 01:22:46 PM »

Duty Cycle:
My experience with duty cycle and the CMCD amps is that you should get as close to 50% as you can.  Apparently, CMCD are more sensitive than other switchers:
(see photo)
Symmetry between banks is more important than the actual number.  Obviously you can only get as close to 50% as the speed of your circuit will allow.  For me at 20m that is around 48%, and the drop in efficiency as I got away from it is noticeable.
Efficiency aside, getting the most out of your transistors/circuit means maximizing the on time (area under the curve and all).

MOVRF- PM sent

Chuck KJ7AGO

* Drain efficiency vs duty cycle for PAs.png (332.34 KB, 1530x882 - viewed 365 times.)

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« Reply #27 on: January 16, 2023, 08:45:46 AM »

Hi friends! It surprised me to see this topic here...I am glad actually! The concept of the RF amplifier published in my blog is not new effectively, and it is based on RF books and papers. Name can vary from Inverse class D, CMCD, class E/F, class E/Fodd and more. The W1VD design uses broadband output transformer, digital drivers etc... I am sure there are many other circuits on the internet spreaded. It is worthy to read books and looking for valuable information, one just need to adapt to the particular requirements, that's all.
The most important thing is very simple to build, with material one can find anywhere. No digital drivers, very effective analogue driving (but tuned circuit although), built with materials easy to find here in Argentina at least, AND VERY VERY EASY START IT UP (COMISSIONING) compared to Class E.
I recommend you to try it, honestly. A lots of ham operators here have built this design.
I have a design of 1kW Class 1/D with just 2 MOSFETs that works terrific...I will publish soon

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Posts: 1997


« Reply #28 on: January 17, 2023, 07:08:14 AM »


   Welcome to AMFone! I started this thread based upon observing several Blogs from South American Hams. It sure seems that AM on 40m is alive and well in your area.

Here in Texas, 7160 is often used for AM, and has a long history. Your 1KW two transistor class 1/D sounds very interesting.

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