Some Kind of Class-E Related Mess

143

01:19:24

To the left is the signal input which then goes through an RLC network to the base of the class-C transistor which then amplifies the signal to power the base of the class-E transistor (it needs amplification because the BJT requires current and a MOSFET can’t be used because it’s high capacitance will not work with the high frequencies). Above the class-C is another RLC network to smooth the power consumption (from much push pull to some constant pull). You may notice a missing 5pF capacitor in the class-E network, but that is substituted by the parasitic capacitance of the transistor.

published 8 years ago

thebugger

8 years ago

I actually tried the diode bias, and it's too aggressive on the transistor. It keeps overheating, even when it's tuned and working in the best operational area. I switched to a choke bias, and it keeps clogging the transistor when the power gets too high. Furthermore it turns out my circuit is tuned perfectly, but theoretically it's veeeery far from the tuning point. I'm not sure how to progress with my design. I've been stuck for a few days now, dealing with transformation networks and shit.

jason9

8 years ago

You’re building my circuit?

thebugger

8 years ago

No, I'm working on a class C amp, I just tried the diode bias. Too aggressive. Transistor keeps overheating.

jason9

8 years ago

Ok.

hurz

8 years ago

If the transistor is getting to hot, then its not in class c mode and its to LESS aggressive, cuz it does not reach class c operating mode, its more in class a, shit happends to noobs. Buggzy.buggzy.buggzy...

thebugger

8 years ago

Nope, it's class C alright. The collector current is typical for the calculated output. Just I don't know, the diode probably adds some capacitance to the b-e junction, that the input transformation network can't tune out or something.

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