Medium frequency receiver

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squb

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Hello all.

I have problem with designing radio receiver which working on one frequency 457 kHz. I realize that I could use standard medium frequency radio receiver scheme
and adjust circuit for 457 kHz.
I would like to ask you guys ,if it is possible to build such a circuit where mixer and frequency conversion to 455 kHz is not used.

I would like to try build circuit where signal (CW modulation) is received by by ferrite rod antenna then signal is toward to band pass filter ,then to class C power amplifier and then to A/D converter embedded in MCU.

Do you think above circuit has chance to work ?
 

i don't think that a superhet with an IF of 455kHZ will work with an input signal of 457 kHZ. If it is going to be for a fixed (457 kHZ) reception only, I would use a domestic superhet with the mixer/oscillator re-configured as an RF amp. Get an old one with IF transformers and not fixed ceramic filters (can't change the frequency of these). Take your output from across the volume control. With CW, all you will get is a change of DC, depending if the carrier is on or off. It might be worth disabling the AGC circuit, because in the absence of the carrier, the gain of the set will rise, the noise through it will increase, which will result in an increased DC level at the volume control. Why do you need a class C amplifier?
Frank
 

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