Summer 2013: Montreal Doppler 3V2

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The Montreal Doppler 3V2 is a pseudo-doppler radio direction finder designed by VE2EMM of the amateur radio community. The schematic, parts list (there were some edits) and build details are located at Montreal Doppler 3V2

The final version of the kit that was assembled featured an acrylic case and a 3.5mm audio output jack.

Build Notes

• The case can be completely disassembled from the PCB, since the wires connected to all components on the front acrylic panel are attached to the board using header pins and female connectors. Even the LCD can be completely disconnected.
• Shorting the two header pins near the "select" button wire connectors is used to ground the lesser voltage on the "menu" potentiometer. This increases the range of menu options, as specified in the Montreal Doppler build instructions.
• Cutouts in the front acrylic panel provide access to pins for the receiver input and pins to drive and power the antenna array. Instructions for connecting the antennas to the PCB pins are in the Montreal Doppler build instructions.
• The audio jack is set up to only output mono sound.
• Resistor #55 (R55) needs to be replaced with a 680kOhm resistor.
• Regardless of the color of wires and the background color of the header pins that they connect to, the wire identified as ground connects to the header pin that is colored black.
• The LCD screen is held in by the row of header pins and two #2-56 screws connected to the LCD PCB. These screws loosely rest inside the 0.25" tall #4-40 threaded spacers attached to the surface of the main PCB. The interaction between the threads on the #2-56 screws and the internal threads of the spacers helps prevent the LCD PCB from bounding around. An ideal solution to this problem would be to only use #2-56 screws, standoffs, and spacers for the holes concentric with the LCD PCB mounting holes.