Title: Older PostPost by: DMOD on March 03, 2016, 10:37:11 AM
Some time ago there was a post on the old ClassE forum by a Mr. Carter of a 200W Push-Pull 1710 kHz ClassE transmitter which could form the basis of a 160 meter transmitter.
However, when I ran the numbers, the drain capacitor values of the final's didn't seem to correlate with the results of equations given by Sokal's latest paper or the Textbook by Grebennikov and Sokal, .Switchmode RF Power AmplifiersDoes anyone recall that post or the discussion surrounding Carter's post? Thanks, Phil - AC0OB Title: Re: Older PostPost by: KD6VXI on March 03, 2016, 01:29:40 PM
Engineers in Iran have taken to new math equations. Iirc, it was dealing with the irf640 at 11 meter ism. He used a different values than socal, etc. Equations give.
I can try to dig it out of the phone. Pdf file, and I've got about 20 gig of them on the phone. He does give the basics for the way he generated his values, as well as almost every value for a working amplifier. --Shane KD6VXI Title: Re: Older PostPost by: steve_qix on March 04, 2016, 04:39:28 PM
Hmm... Class E RF amplifiers for 160 meters are dirt simple. I would start with a better design.
How much power do you want to run? Regards, Steve Title: Re: Older PostPost by: DMOD on March 05, 2016, 12:17:55 AM
Engineers in Iran have taken to new math equations. Iirc, it was dealing with the irf640 at 11 meter ism. He used a different values than socal, etc. Equations give. I can try to dig it out of the phone. Pdf file, and I've got about 20 gig of them on the phone. He does give the basics for the way he generated his values, as well as almost every value for a working amplifier. --Shane KD6VXI Thanks Shane. I know he gave equations but what were the source of those equations? When I ran the classE equations on Matlab the values of the drain caps on the finals did not jive with his results. ME wonders what power rating he was using to obtain those values. As far as simplifying his design there are many ways to do it. For example, using IXDN614CI instead of his bipolar driver circuit saves many components. I would use my timing and pulse-width controller to get optimum delay and pulse width. As far as power, I want about 250 Watts carrier with a PDM modulator. I have Steves PDM card populated and I have a T-400A core. I do like the idea of the push-pull circuitry as per Dave Cripe's design. Phil - AC0OB Title: Re: Older PostPost by: KD6VXI on March 05, 2016, 01:43:11 AM
Sorry Nathan, Sokal was destroyed by autospell above. Love android. Mostly. Lol
I'm not sure his source. I believe Hasani arrived at them empirically. I ran across his article while trying to design a ten meter rf deck. Wince I used irf640s in my pwm, it was a no brainer. I tried to paste a link to the article pdf I'm referencing, but it was a couple hundred characters long.... Irf640 and Hasani and class e in Google will return the pdf file for those interested. I did manage to build a 2 pill 640 deck on 29 mhz. Gave me a 50 Watt carrier modulated 100 pct. Really cheap, considering it was irf640 and not mrf devices! Didn't go bigger as that overdrive the amps here quite well. Now that sanctions are lifted, maybe you could ask the author his math equations directly? Not sure it's necessary at 160 though. His equations are to allow class e at higher freq / higher output C of the devices. --Shane KD6VXI Title: Re: Older PostPost by: steve_qix on March 05, 2016, 11:12:12 AM
Single ended push-pull is really good because overlap, while compromising the efficiency, does not cause any other problems. Standard push pull is more critical in adjustment. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
As far as calculations - I have not found any of the models to work particularly well. At least that's been my experience. |