Homemade Superhet for Medium Wave with Crystal Filter

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 groundig is made by a piece of aluminium foil.

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.