The SMD Receiver

Joachim Köppen Kiel 2018

The latest version of my receivers is built with surface mount devices:

It neatly fits into the breast pocket of a shirt, and thus the antenna is the most cumbersome of the equipment (Click on image to enlarge). From left to right: input section, active low pass filter, audio section, and the 9 V battery. The blue square box is the trimmer resistor to set the level for the tape recorder output.

The circuit is as described on the other pages. Here is the input section:

But instead of the simple 18 kOhm/2 nF low pass there now is a low pass followed by a bridged-Tee to reject emissions from local VLF transmitters operating near 25 kHz. The curve shows the filter's overall response:

Then follows an active low pass filter for 10 kHz:

and the audio amplifier:
Although the circuit schematics indicate a supply voltage of 12 V, the receiver works well with battery voltages as low as 6 V.

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last update: Apr 2018 J.Köppen