2007-02-07
AM Receiver IF Development
I did some work towards the receiver, building a MK484 based AM IF as discussed previously. It works beautifully, the AGC has pretty good dynamic range. Just dangling the signal generator clip lead need the IF input pad produces a clean AF output signal.
Note the three dropper diodes that along with a 2N3904 (or any old generic NPN) implement a voltage regulator. The IF system pulls less than 1 mA. Of course the rest of the circuit will burn many times more power, but the MK484 is capable of implementing a sub-500 uA complete TRF detector, especially with an active regulator when using higher supply voltages. This makes it an excellent device for battery operated equipment.
I'll write up the circuit diagram shortly.
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