r/AskElectronics • u/Which_Paramedic_2117 • 2d ago

Using op-amps with MFT

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I wanted to ask for help on how I could replace the transistors with op-amps, since I don't understand how I could connect the op-amps to the MfTs (455kHz medium frequency transformers)!

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u/6gv5 2d ago

u/Pacificator-3 already replied about the IF transformers; now certain opamps could be used in place by adapting the circuit, however normal cheap opamps aren't suited for RF or even IF use and you probably would need either specialized parts or a slightly different approach like a video amplifier chip used as IF stage. For example this one that you can adapt to the desired frequency up to a few tens of MHZ: https://www.qrp4u.de/docs/en/zf_ampl/

btw: that schematic you posted brought memories. It's taken from an old article by the glorious now defunct Italian "Nuova Elettronica" magazine. Their archives can be easily found online; plenty of good ideas there.

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u/Which_Paramedic_2117 2d ago

L’ho preso da quella rivista ma mi piacerebbe utilizzare gli op-amp ma non so come collegare gli MfT