hello. i am joao, and i am a radio amateur. i have built several small projects before, from antennas to small am/ssb transmitters, receivers, and small amps.
i am trying to correctly build a push pull mosfet amp. i am using a yeasu ft757 as an exciter for both am or ssb. i would like to build this amp and then a bigger one so i could use it on 80m am nets or maybe sometimes on 40m as a ssb amp, for a few more db's. i have built an amp like in the schematic, but i tried to test it with only only mosfet, out of curiosity. with the drain connected to a 100n capacitor and to a dummy load, i can get around 40, 50w max, with different mosfets. at around 2.5v bias voltage and 38v dc supply. when transmitting, the voltage rises on the bias potentiometer, as if rf is coming into the bias dc line. and the audio on am sounds distorted, kind of fuzzy. with a modulated input ranging from 0.25w, to around 2watts.
thanks for reading. any help is very appreciated.
joao g.
i am trying to correctly build a push pull mosfet amp. i am using a yeasu ft757 as an exciter for both am or ssb. i would like to build this amp and then a bigger one so i could use it on 80m am nets or maybe sometimes on 40m as a ssb amp, for a few more db's. i have built an amp like in the schematic, but i tried to test it with only only mosfet, out of curiosity. with the drain connected to a 100n capacitor and to a dummy load, i can get around 40, 50w max, with different mosfets. at around 2.5v bias voltage and 38v dc supply. when transmitting, the voltage rises on the bias potentiometer, as if rf is coming into the bias dc line. and the audio on am sounds distorted, kind of fuzzy. with a modulated input ranging from 0.25w, to around 2watts.
thanks for reading. any help is very appreciated.
joao g.
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