Re: Looking to build RF detector probe for low frequency
I'm not sure I'd recommend the Haig circuit if demodulation is also required because I think there will be a fair bit of distortion in the demodulated signal. At small signal levels the distortion will be in the diode detector and at larger signal levels (i.e. a large waveform at the drain in high gain mode) the JFET will become non linear.
I guess it would still be OK if you are content to accept something like a wonky sinewave from the detector. However, if reasonable fidelity is required then I'd try a different approach. Either that or try and improve the Haig circuit if you want to reuse as many parts as possible.
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Regards, Jeremy G0HZU
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