... frequency counterSpecifications:1.Frequency: LW1641: 0.1Hz--2MHz, LW-1642: 0.1Hz--5MHz LW-1643: 0.1Hz--10MHz2.Output waveform: Sine, Triangle ... : 90:10--10:907.Rising Edge of Square: LW-1641: less than 100ns, LW-1642: less than 50ns, LW1643: less than 50ns ... Response: 0.1Hz--100MHz: Less than ±0.5dB 100KHz--2MHz (LW-1641): Less than±1dBTTL/COMS Output1. Level: TTL low level ...