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class C amplifier gain

The class-C amplifier in question used 6L6s IIRC. They where driven by a transformer circuit that I never quite figured out at the time. The output was a transformer that sent a nominal 100V signal to where the speakers were. The design seemed to be optimized to use as few tubes as you can to make as much noise as you can. I doubt that much time was spent on sound quality.

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Yes it is a nice idea.

These days, I have to use MOS parts in the output and the RF power is not for radiation. The biggest issue I had was making the RF have as little near carrier noise as I could without making things run too hot. Class C with a very strong gate drive and a very quiet power supply turned out to work the best. With bipolars it seemed that a large value of bias resistance and running the part short of bottoming worked the best. The noise that matters is from about 0.01Hz to

500KHz offset from the carrier. I can't trust the high Q to clean it up because I just can't seem to get inductors with a Q over a billion or two.
Reply to
MooseFET
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Sometimes those mode variations are also called Class S. Usually for RF amplifiers only. Moreover this technique (for AM use) has issues with expensive filtering for the first few harmonics, especially at significant power (>10 W).

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Reply to
JosephKK

I wasn't aware that mini-circuits had products in that low frequency and higher power corner of the market.

--=20 Transmitted with recycled bits. Damnly my frank, I don't give a dear

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Reply to
JosephKK

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I use to have two books that were a collection of application notes on RF amplifiers from Motorla. That was back in the early 90's. I learned everything I use to know about RF from them. They grew legs one day and walked away... sigh. I can't remember the names and a quick search of the web didn't turn up anything that looked familiar. But perhaps someone here will know and we can both find used copies on the web.

George H.

Reply to
George Herold

The ones with the nice suede-texture covers? The one I have is "Radio, RF, and Video Applications", DL413/D, 1993.

Cheers,

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
Reply to
Phil Hobbs

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Hmm, That name does not ring a bell, but that might be it. The date is certainly about right. The ones I had were blue colored paperbacks. (at least that's my memory) There was a second skinnier volume that might have been a product selection guide. Would you recommend "Radio, RF, and Video Applications" to someone learning RF amplifier design? That was my situation at the time and I remember them fondly....

George H.

Reply to
George Herold

Dunno--I'm not a big RF expert, but what I know about it, I mostly learned from colleagues. It has a lot of designs for PAs based on old transistors.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
Reply to
Phil Hobbs

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Maybe not an expert, but you know way more than me... (I've read your book after all.) My only colleague at the time was barely more knowledgeable than myself. (but it's good to have at least one colleague.)

If PA stand for pulse amplifier then it could be the book. I was building the amp stage for a 17MHz NMR... 1mW in and a few watts out... but only for a couple of microseconds every second or so.

George H.

Reply to
George Herold

Those notes were probably written by Helge Granberg. I haven't checked, but many of them are likely float around the web by now. I have many of them in a loose stack at home.

Jeroen Belleman

Reply to
Jeroen Belleman

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