Re: Improving Selectivity In Vintage Receivers
Emitter followers working into loads that have potentially rather variable impedance / frequency curves can be problematic, you can easily enter the world of negative resistance and things can oscillate at unexpected frequencies..
This is why, specially at microwave frequency, you may find a 3dB or 6dB resistive pad (often a classic 3-resistor pi network) between stages. You lose gain but gain stability!!
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