The 2 level data slicer ('Hamcomm modem') is connected to the discriminator output of your receiver and to your PC's RS232 port. The interface converts the baseband signal from the discriminator into levels that can be read by your computer's serial port. That should be a 'real' serial port. An RS232 to USB converter or a PCMCIA/PCI card with one or more serial ports will not work. For use with a USB port, the USB interface has been developed.

The interface is powered from the serial port (lower part of the schematic diagram).

Circuit diagram of a 2-level data slicer.
Pins are valid for a 9-pin D-connector

The interface in a 9-pin D-connector

2 level interface

You don't need a PCB for a 2 level interface. The components fit inside a 9 pin D connector. To fit everyting in, I use miniature capacitors of 10 uF, but the TL071 is a standard DIL IC. You don't need SMD.

The interface has been discontinued from this site. It has been replaced by the USB interface or RS232 interface