The HP 438A is a dual-channel power meter engineered for precise RF and microwave power measurements in Automated Test Equipment systems. Its independent channels enable simultaneous measurement of two separate power sensors, facilitating direct calculation of power ratios, differences, and absorbed power in transmission lines. The instrument features a four-digit display with 20% over-range capability and five-digit resolution in high-resolution mode, supported by a programmable digital averaging filter that balances measurement speed against accuracy. Up to 19 operating states store in non-volatile memory for rapid recall. The compact front panel design optimizes rack-mount installations.
Technical Specifications
Measurement Range: 100 kHz to 50 GHz (sensor dependent); −70 dBm to +44 dBm (100 pW to 25 W).
Display & Resolution: Four-digit display with 0.001 dB resolution available. Five-digit mode in high-resolution operation. Annunciators indicate measurement mode, calibration factor, offset, range, filter values, and error conditions.
Accuracy:
• Single channel: ±0.5% (linear mode), ±0.02 dB (log mode)
• Dual channel: ±1% (linear mode), ±0.04 dB (log mode)
• One-year worst case: ±1.2%
• Automatic zeroing: ±0.5% of full scale
Calibration: 1.00 mW reference output, ±0.7% factory accuracy (NIST traceable). Calibration factor adjustable 1% to 150% in 0.1% steps. Automatic self-calibration to 1.00 mW.
Measurement Modes: A, B, A−B, B−A, A/B, B/A with power difference display capability.
– Key Features
• Dual independent channels for simultaneous two-sensor measurement
• Storage of 19 operating states in non-volatile memory
• Programmable digital averaging filter with AUTO mode (0.01 dB resolution)
• HP-IB interface standard (SH1, AH1, T5, TE0, L4, LE0, SR1, RL1, PP1, DC1, DT1, CO)
• Optional MATE programming capability (Option 700)
• Line voltage selectable: 100 V, 120 V, 220 V, or 240 V AC (±5% −10%)
• Power consumption: 65 VA, 35 watts maximum
– Typical Applications
Automated test systems requiring simultaneous dual-channel power measurement; RF and microwave component characterization; transmission line loss and efficiency analysis; sensor comparison and validation.
– Compatibility & Integration
Accepts HP 8480 series thermocouple and diode power sensors. HP-IB programming enables integration into automated test platforms.
