The HP/Agilent 3551A Transmission Test Set is a portable instrument for measuring signal transmission characteristics across voice, program, and data circuits up to 50 kbps. Designed to North American Bell standards (BSTR 41009) and IEEE 743-1984, it performs critical measurements including attenuation distortion, loss, message circuit noise, noise-with-tone, noise-to-ground, and single frequency interference. The instrument handles both 2-wire and 4-wire balanced circuits with selectable impedances of 135 Ω, 600 Ω, and 900 Ω.
## Technical Specifications
**Receiver**
• Frequency range: 40 Hz to 60 kHz
• Dynamic range: +15 dBm to -70 dBm
• Level resolution: 0.1 dB
• Message circuit noise: 0 dBrn to +85 dBrn
• Noise-with-tone range: 10 dBrn to +85 dBrn
• Noise-to-ground range: 40 dBrn to +125 dBrn
• Noise measurement resolution: 1 dB
• Detector type: Quasi RMS
• Noise weighting filters: C message, 3 kHz flat, 15 kHz flat, Program
• Sample rate (noise level): 2 per second
**Transmitter**
• Frequency range: 40 Hz to 60 kHz
• Frequency resolution: 1 Hz (40 Hz to 10 kHz); 10 Hz (10 kHz to 60 kHz)
• Level range: -10 dBm to -60 dBm (40 Hz to 60 kHz); +6 dBm to -60 dBm (hold tone)
• Level resolution: 0.1 dB
• Sample rate (tone): 10 per second
**Power and Physical**
• AC line input: 100 V, 120 V, 220 V, 240 V ±10%; 48 Hz to 440 Hz
• Power consumption: 15 VA
• Battery operation: 4–6 hours continuous; 12–16 hour recharge time
• Maximum input/output voltage: 300 V dc metallic or 200 V peak longitudinal
• Dimensions: 16 × 14 × 10 in
• Weight: 6.6 kg (14.5 lb)
## Key Features
• Digital LED display with quasi RMS detection
• Built-in speaker for signal monitoring
• Operates on AC mains or rechargeable battery
• Connectors: TIP and RING binding posts, WECO 310 jack
• Optional HPIB interface board (5060-3551) available
## Typical Applications
Network maintenance and qualification of telecommunications and data communication systems. Ideal for characterizing transmission performance in carrier and circuit installations subject to North American Bell standards.
