Marconi IFR Aeroflex 893B – AF Power Meter

The Marconi IFR Aeroflex 893B is a precision audio frequency power meter engineered for accurate power measurement across balanced and unbalanced input configurations. It delivers direct-reading display in watts and decibels relative to 1 mW, with ten selectable ranges spanning 300 µW to 10 W full-scale deflection. The instrument provides ±7% accuracy on power measurements from 100 Hz to 10 kHz, with input impedance selectable from 48 discrete values between 2.5 Ω and 20 kΩ. Temperature-compensated detector circuitry ensures stable operation across its specified range, making it suitable for RF power validation, audio system characterization, and precision component testing where impedance matching and frequency response matter.

– Technical Specifications

• Frequency Range: 20 Hz to 35 kHz (specified range)
• Power Measurement Range: Ten ranges with full-scale deflections from 300 µW to 10 W (300 µW, 1 mW, 3 mW, 10 mW, 30 mW, 100 mW, 300 mW, 1 W, 3 W, 10 W)
• Input Impedance: Selectable from 48 impedances; 2.5 Ω to 20 kΩ (1× range) and 0.625 Ω to 5 kΩ available via center-tap configuration
• Accuracy (5°C to 35°C): ±7% of f.s.d. ±10 µW for power at 100 Hz to 10 kHz; ±7% for impedance at 1 kHz
• Frequency Response (relative to 1 kHz): <1 dB down at 50 Hz; typically 0.7 dB down at 20 kHz
• Display: Direct reading in watts and dB (ref. 1 mW)
• Operating Temperature: 0°C to 55°C
• Storage/Transport: −40°C to +70°C, up to 90% relative humidity; altitude to 2500 m

– Key Features

• Temperature-compensated multi-range detector feeding voltmeter circuit
• Pushbutton range selection across ten power levels
• Bare wire, crocodile clip, 4 mm plug, and spade-lead terminal compatibility
• Optional SINAD filter (Model 50893-321J): 1 kHz center frequency, ≤480 Hz at 3 dB bandwidth, ≥20 dB rejection at 1 W input
• Detector nonlinearity does not affect power accuracy

– Typical Applications

• Audio frequency power characterization in telecom and broadcast systems
• Precision impedance matching verification
• Component and subsystem power validation
• Test signal level measurement in low-frequency analog circuits