Tektronix CMC251 Frequency Counter, 1 Hz to 1.3 GHz

The Tektronix CMC251 Frequency Counter is a multifunction counter which measures the frequency of sine, square, and triangle waves from 1Hz to 1.3GHz. The CMC251 also provides period, totalize and pulse width measurements. The counter has two input channels. Channel A is a standard 1 Mohm input for frequency measurements up to 100MHz. Channel B is a 50 ohms terminated input for use in high-frequency systems. The temperature-compensated, crystal-controlled time base is stable to ±1 part per million per year.