50MHz frequency counter V-meter & SWR/PWR indicator

  
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This is a successor of the PIC16C71 4-digit LED f-counter & V-meter. Some hard to find parts used in the previous version, which are out of production for some time, has been omitted. A rather early PIC16C71 has also been replaced by 28-pin device PIC16F876. The later is capable of driving 4 digit LED display in multiplexed mode while measuring fr
50MHz frequency counter V-meter & SWR/PWR indicator - schematic

equency, power supply voltage as well as handle two analog inputs to display SWR/PWR signal strength in a bargraph manner. There is no need for external LED display driver chip as well as external data EEPROM since it is already implemented in PIC16F876. Reduction in the number of used chips also results in smaller dimensions of the counter compared to its predecessor. Measurement of the input voltage at two analog inputs, simultaneously displayed as bargraph (PWR/SWR or S) indicator. The input sensitivity could be chosen between 0. 25V, 0. 5V, 1. 0V and 2. 0V for maximum bargraph indication. Power save mode: Automatic display shut-down in case the push-button action or frequency change does not occur for a certain time. Display switches on againt after frequency change or push-button action. The available shut-down time periods are 3s, 10s, 30s, 60s, 120s, 180s and 240s. This function can be disabled in set-up menu. Programmable frequency offset added or subtracted from measured frequency, settable in the range of 0 to 99, 999. 9 kHz. This is convenient for use with heterodyne type of RX/TX In operating mode a push-button allows the user to choose between the frequency, bargraph or supply voltage to be displayed. The frequency display mode can also be changed with longer (>1s) push-button pressing. For example if the frequency to be displayed is 14. 065. 9 MHz the user will see on the four digit display either "065. 9",...



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