frequency counter PIC-Based Digital

  
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Apply power to the frequency counter and set the coarse (top pot) and fine (bottom pot) adjustments to show zero frequency on the display. Turn the pots counter-clockwise to set to zero. Sometimes the counter will show all squares and no digits. Disconnect and re-apply power and the digits should show. Also, turn the viewing angle of the display
frequency counter PIC-Based Digital - schematic

to make sure they are visible. _Install a 74HC4046 in the middle socket. This will allow VFO energy to reach the counter. (Or remove the short on the VFO cable, leave the HFO cable shorted. ) Be very careful of reverse polarity connections. A reverse polarity connection to the frequency counter will blow the voltage regulator (78LO5). Use a diode at the B+ input to the Frequency Counter if you think you might make a mistake. Band side of the diode goes to the outside where you will be attaching power. _Set the 2/8 ceramic trim pot (labeled 14. 068) to its middle position. Line up the slot in the adjustment screw with the capacitor pins, with the rotor plate on the end with the arrow. The rotor plate is the part of the top with the metallic color. If the frequency is too high, add a turn to the toroid. (This may require rewinding the toroid for a clean appearance, but having the frequency read too high, >15MHz, is unlikely. ) _Secure the VFO toroid by whatever means you have decided. Some options are a small plastic wrap, a 4-40 screw/nut and 3/16" rubber grommet (cut to fit into the center of the toroid), or pour wax from a candle (let wax cool before proceeding). Picture _Set the receiver to 40 Meters. Bandpass switch to the 40/30 side and the Crystal Filter switch to the 40/20 side. One LED should be on next to the 10. 545 relay. The offsets and the adding/subtracting are done at Pins 12 and 13 of the PIC16C71. Pins 12...



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