This is a frequency counter based on PIC16F84 for 100Hz-2.5GHz, using LCD 16 chara.x 2 lines ,TCXO 12.8MHz(1ppm ) and PIC16F84. The Voltage(0-510mV) of the input signal is also indicated on the LCD , therefore tuning of the coil can be conducted while checking the frequency. Furnished with IF offset-function, this can be applied for the frequncy display of the home brewed transeiver. source

This is a Frequency Counter and Timer circuit based on AVR.In counter mode it provides 1Hz resolution up to 100Mhz. In timer mode maximum resolution is 0.0000001 Hz up to 1Hz. Resolution is reduced by one digit for each additional decade. Multiple frequency updates per second by employing a sliding window for calculation.source