This superheterodyne for medium wave has a crystal filter with about 6 kHz bandwith an a center frequency of 4,4 MHz, which is is also the IF. The mixer is based on a SA612. You don´t have to wind coils. This receiver needs only some fixed inductors.
I realized the receiver in the manhattan style circuit technique. A good grounding avoids unwanted oscillation and hum.
The receiver was built in the manhattan style technique.
The lowpass filter in the frontend in order to supress the mirror frequency. R1 is the attenuator in order to avoid distortions. Cut off = 2 MHz.
The Lowpassfilter is designed with ADDE-Filterdesign.
The filter circuit in manhattan style.
The measured filter curve.
The mixer and LO.
The IF crystal filter.
Frequency curve of the IF filter realized by 3 crystals.
IF-amplifier and AM-demodulation.
dAF-preamplification with automatic gain control for the AF.
5 Volts and 12 Volts PSU.
The performance of the receiver:
Bandscan on mediumwave on a novemberevening 2013. The antenna is 30 m long wire.