The Keysight (Agilent/HP) 5345A is a high-performance 500 MHz universal frequency counter and timer. It utilizes advanced reciprocal counting techniques to deliver a constant 9 digits of resolution per second of gate time across its entire frequency range. Offering an exceptional 2 ns single-shot time interval resolution—which scales down to 2 ps with averaging—the 5345A serves as a versatile mainframe. Its front-panel plug-in compartment supports various frequency extension converters, expanding its measurement capabilities up to 40 GHz for microwave, millimeter-wave, and pulsed RF applications.
Specifications
General
| Parameter | Value |
|---|---|
| Interfaces | HP-IB (GPIB) via Option 011 or standard in later revisions; Rear-panel external gate input; Rear-panel gate output |
| Display | 11-digit red LED display with sign and exponent indicators |
| Plug-in Compartment Compatibility | Accepts HP 5353A, HP 5354A, and HP 5355A plug-ins |
Physical
| Parameter | Value |
|---|---|
| Power Supply | 100 / 120 / 220 / 240 VAC (+5%, -10% selectable), 48 to 66 Hz, 150 VA maximum |
| Operating Temperature | 0 to 50 °C |
| Dimensions (W×H×D) | 425.4 mm × 133.4 mm × 495.3 mm |
| Weight | 15.4 kg |
Input Channels A & B
| Parameter | Value |
|---|---|
| Frequency Range (DC Coupled) | DC to 500 MHz (Channels A and B) |
| Frequency Range (AC Coupled) | 20 Hz to 500 MHz (Channels A and B) |
| Input Impedance | Selectable: 50 Ω (nominal) or 1 MΩ shunted by < 30 pF |
| Input Coupling | AC or DC, selectable |
| Input Attenuation | x1 or x10, selectable |
| Input Sensitivity (Sine Wave) | 20 mV rms (DC to 500 MHz) |
| Input Sensitivity (Pulse) | 50 mV peak-to-peak (minimum pulse width 1 ns) |
| Maximum Input Damage Level (50 Ω) | 5 V rms (fuse protected in connector) |
| Maximum Input Damage Level (1 MΩ) | 250 V rms (DC to 400 Hz), decreasing to 10 V rms at 500 MHz |
| Trigger Level Range | -2.5 V to +2.5 V (x1 attenuation), adjustable or preset to 0 V |
Measurement Capabilities & Modes
| Parameter | Value |
|---|---|
| Measurement Modes | Frequency, Period, Time Interval, Time Interval Average, Ratio, Totalize |
| Frequency Resolution | 9 digits per second of gate time |
| Single-Shot Resolution | 2 ns |
| Averaged Resolution | Down to 2 ps |
| Period Measurement Range | 2 ns to 10^4 s |
| Time Interval Range | 10 ns to 10^4 s (single-shot) |
| Frequency Ratio Range | DC to 500 MHz on Channels A and B (Ratio A/B) |
| Totalize Range | 0 to 10^11 counts |
Timebase & Reference Oscillator Options
| Parameter | Value |
|---|---|
| Standard Timebase Reference Frequency | 10 MHz |
| External Reference Input Frequency | 10 MHz |
| External Reference Input Amplitude | > 1 V rms into 500 Ω |
| External Reference Output Frequency | 10 MHz |
| External Reference Output Amplitude | > 1 V p-p into 50 Ω |
Gating, Triggering & Math
| Parameter | Value |
|---|---|
| Gate Time Range | 100 ns to 10 s (in decade steps) |
| External Gating Level | TTL compatible, rear panel input |
Connectivity & System Interfaces
| Parameter | Value |
|---|---|
| External Arming Input | Rear-panel arming inputs for Start and Stop, TTL compatible |
Plug-In Compatibility
| Parameter | Value |
|---|---|
| Frequency Extension Compatibility (5355A) | Extends frequency measurement range up to 18 GHz using HP 5355A Automatic Frequency Converter |
| Frequency Extension Compatibility (5356C) | Extends frequency measurement range up to 40 GHz using HP 5356C Converter Head |
Power & Environmental
| Parameter | Value |
|---|---|
| Storage Temperature Range | -40 °C to +75 °C |
Timebase
| Parameter | Value |
|---|---|
| Standard Timebase Aging Rate | < 3 × 10^-7 per month |
| Standard Timebase Temperature Stability | < 2.5 × 10^-6 (0 °C to 50 °C) |
| Standard Timebase Line Voltage Stability | < 1 × 10^-8 for 10% line voltage change |
| Option 001 Oven Timebase Aging Rate | < 5 × 10^-10 per day (after 24-hour warm-up) |
| Option 001 Oven Timebase Temperature Stability | < 1 × 10^-9 (0 °C to 50 °C) |
| Option 001 Oven Timebase Line Voltage Stability | < 5 × 10^-10 for 10% line voltage change |
Triggering
| Parameter | Value |
|---|---|
| Auto Trigger Frequency Range | 30 Hz to 500 MHz |
| Auto Trigger Duty Cycle Range | 10% to 90% |
| Trigger Slope Selection | Positive (+) or Negative (-) independent for Channel A and Channel B |
Performance
| Parameter | Value |
|---|---|
| Minimum Pulse Width | 1.0 ns |
| Channel-to-Channel Time Interval Systematic Delay | < ±1.5 ns (typical) |
Inputs & Outputs
| Parameter | Value |
|---|---|
| Input Capacitance (1 MΩ) | < 30 pF |
Rear Panel Inputs & Outputs
| Parameter | Value |
|---|---|
| Rear Panel Gate Output Amplitude | ≥ 2.4 V (high level), ≤ 0.4 V (low level) into 50 Ω |
| Rear Panel Gate Output Function | Provides TTL level pulse indicating main gate status (low when gate is open) |
| Rear Panel Trigger Level Outputs | Approximately 1 V per volt of trigger level in ×1 attenuator setting, 0.1 V per volt in ×10 setting |
Options
| Parameter | Value |
|---|---|
| Option 011 HP-IB Capability | Provides full remote programmability and data output capability via IEEE-488 (HP-IB) |
| Option 012 Digital Output Function | Provides parallel BCD data of display digits and status via rear-panel 50-pin connector |
Technology
Reciprocal Counting & Sub-Nanosecond Time Interval Averaging
Applications
Precision frequency, period, and time-interval measurements for radar, telecommunications, and RF/microwave engineering