Fluke PM6681 High Resolution Programmable Timer / Counter Analyzer

The Fluke PM6681 High Resolution Programmable Timer/Counter Analyzer delivers picosecond-level time interval resolution and multi-gigahertz frequency measurement capability for precision development, calibration, and production testing. This dual-channel instrument (expandable to three) captures single-shot time intervals to 50 ps and averaged measurements to 1 ps, with frequency coverage from DC to 4.5 GHz (expandable to 8 GHz). It combines programmable memory for 20 instrument setups, GPIB automation, and TimeView™ PC analysis software for comprehensive signal characterization across phase, jitter, pulse width, rise/fall time, and duty factor measurements.

– Technical Specifications

Time Interval & Frequency
• Single-shot resolution: 50 ps (100 ps for PM6681R)
• Averaged resolution: 1 ps (10 ps for PM6681R)
• Frequency range: DC to 4.5 GHz base; up to 8 GHz with options
• Measurement rate: 8,000 readings/s to internal memory; 250 readings/s via GPIB; 40,000 readings/s for continuous single-period measurements

Input Channels
• Dual channels (optional third channel)
• AC or DC coupling; 1 MΩ // 15 pF or 50 Ω impedance options
• Maximum sensitivity: 20 mV rms below 100 MHz
• Trigger level: 1.25 mV vertical resolution with adjustable display readout
• Attenuation: ×1 or ×10

Time Base Stability
• Standard: 5 × 10⁻⁷/month
• Very High Stability Oven: 1 × 10⁻⁸/month
• Rubidium Reference: 5 × 10⁻¹¹/month

Reference I/O
• Input: 1, 2, 5, or 10 MHz at >200 mV rms
• Output (PM6681R): 5 × 10 MHz and 1 × 5 MHz at >0.5 V rms sinewave into 50 Ω load

– Key Features

• 20 programmable setups with non-volatile storage (10 user-protected)
• Frequency, period, time interval, phase, jitter, pulse width, rise/fall time, duty factor, and voltage measurements
• Arming and gate outputs for external synchronization
• Trigger level outputs available
• GPIB interface standard for automated test sequences
• TimeView™ software provides graphing, smoothing, and histogram analysis

– Electrical & Integration

• Power: 90–265 V rms, 45–440 Hz
• Consumption: 35 W (PM6680/681); 100 W peak / 47 W continuous (PM6681R)
• GPIB interface standard on /016 models; optional on base models
• Analog voltage output available

– Typical Applications

Precision timing validation, phase/jitter characterization, frequency stability analysis, frequency ratio measurement, and signal conditioning in metrology and production environments requiring sub-nanosecond resolution.