HP / Agilent 5384A 10 Hz to 225 MHz Frequency Counter

The HP/Agilent 5384A is a dual-channel frequency counter covering 10 Hz to 225 MHz with up to 9-digit resolution. Channel A addresses low-frequency signals from 10 Hz to 100 MHz with 15 mVrms sensitivity at 50–100 MHz and 25 mVrms at 10–50 Hz, while Channel B extends coverage to 225 MHz with 10 mVrms sensitivity at 50–200 MHz. The instrument measures frequency, period, ratio, and totalize functions using interpolar-enhanced reciprocal counting for cost-effective accuracy. A 10 MHz timebase with <3 × 10⁻⁷ per-month aging and <5 × 10⁻⁶ temperature stability over 0°C to 50°C ensures precise measurements across telecommunications, R&D, and automated test environments.

## Technical Specifications

**Frequency Measurement**
• Frequency range: 10 Hz to 225 MHz
• Resolution: Up to 9 digits per second
• Measurement functions: Frequency, period, ratio, totalize
• Counting method: Interpolar-enhanced reciprocal counting

**Channel A (10 Hz – 100 MHz)**
• Sensitivity: 15 mVrms (50–100 MHz); 25 mVrms (10–50 Hz); 45 mV pk-pk (5 ns minimum pulse width)
• Dynamic range: 45 mV to 4 V pk-pk
• Coupling: AC
• Impedance: 1 MΩ nominal || <25 pF (X1); 500 kΩ nominal || <25 pF (X20)
• Attenuator: X1 or X20; X40 below 50 Hz
• Low pass filter: 100 kHz (nominal 3 dB point)
• Trigger level control: ±2.5 Vdc adjustable

**Channel B (50 MHz – 225 MHz)**
• Sensitivity: 10 mVrms (50–200 MHz); 15 mVrms (200–225 MHz)
• Dynamic range: 10 mV to 1 Vrms
• Coupling: AC
• Impedance: 50 Ω nominal
• Attenuator: Manual X1 to X5 (0–14 dB nominal); Auto AGC mode
• Damage level: 350 VDC + 5 Vrms AC

**Timebase**
• Frequency: 10 MHz
• Aging rate: <3 × 10⁻⁷ per month
• Temperature stability: <5 × 10⁻⁶ (0–50°C, referenced to 25°C)
• Line voltage stability: <1 × 10⁻⁷ (±10% variation)
• Optional TCXO available for enhanced stability

**Display**
• Type: Programmable alphanumeric LCD
• Digits: 12-digit display with variable control (3–11 digits)

## Key Features

• Dual-channel architecture covers low to high RF frequencies
• Extensive input conditioning with low pass filtering and manual/automatic attenuation
• Half-rack width form factor for benchtop, rack-mount, or field deployment
• Variable digit display blanks meaningless data for clean signal observation

## Typical Applications

• Telecommunications frequency verification and quality assurance
• Research and development prototyping and characterization
• Automated test equipment (ATE) systems integration