The HP/Agilent 5328A is a 100 MHz universal counter delivering precision frequency and time interval measurements for electronic testing, calibration, and research. Introduced in 1976, this modular instrument combines ROM-controlled measurement cycles with a 9-digit LED display to support frequency, period, time interval, ratio, and totalize functions. Single-shot time interval resolution reaches 100 ns standard, while repetitive interval measurements achieve better than 10 ps resolution down to 100 ps intervals. A comprehensive trigger system with adjustable levels from −2.50 V to +2.50 V and switchable AC/DC coupling accommodates diverse signal types.
## Technical Specifications
**Measurement Ranges**
• Frequency (burst and CW): DC to 100 MHz
• Period and period averaging
• Time interval: 100 ns single-shot resolution; <10 ps for repetitive intervals ≥100 ps
• Ratio (e.g., C/A) and totalize
• Scale and arming functions
**Display & Output**
• 9-digit LED readout with leading zero blanking
• Gate output: TTL levels, rear panel
• Timebase output: TTL levels, rear panel
• Marker outputs: operational to 100 MHz for oscilloscope triggering
**Input System**
• Trigger level range: −2.50 V to +2.50 V
• Trigger level resolution: 1 mV display
• Each channel: attenuator, trigger slope detector, level control, AC/DC coupling
• Switchable impedance (1 MΩ / 50 Ω) with Option 040
**Timebase**
• Standard crystal oscillator; aging <3 × 10⁻⁷ per month
• Line voltage stability: <1 × 10⁻⁷ for 10% change
• Option 010 (oven oscillator): aging <5 × 10⁻¹⁰ per day
**Sampling**
• Measurement interval: <2 ms to HOLD (variable)
## Key Features
• Modular architecture supports frequency extensions to 512 MHz (Option 030) and 1300 MHz (Option 031)
• High-Performance Universal Module (Option 040): 10 ns single-shot resolution, improved averaging, A→B marker, hysteresis compensation
• HP-IB interface (Option 011): remote programming and digital output at up to 500 readings/sec
• Display storage preserves readings between samples
## Typical Applications
Frequency and period characterization, time interval analysis, signal ratio measurements, event counting, and precision calibration in RF and digital circuit validation.
## Compatibility & Integration
HP-IB interface option enables integration into automated test systems with maximum data throughput of 500 readings/sec.
