The Keysight/Agilent/HP 70904A RF Section is the front-end module of the HP 70000 series modular spectrum analyzer, performing initial signal conversion and preparation for downstream analysis. This single-slot module converts incoming RF signals from 100 Hz to 2.9 GHz into a 21.4 MHz intermediate frequency, supporting both AC and DC coupled inputs. The 70904A integrates an input attenuator, limiter, first IF converter, leveling amplifier, local oscillator mixing circuitry, and selective filtering to deliver clean, processed signals to the analyzer backbone. Built for integration into HP 70000 mainframes, it communicates via the Modular System Interface Bus (MSIB) and GPIB, enabling system-level control and inter-module coordination.
Technical Specifications
• Frequency range: 100 Hz to 2.9 GHz
• Output IF: 21.4 MHz
• Input impedance: 50 Ω
• Output impedance: 50 Ω
• Input attenuator: 70 dB adjustable in 10 dB steps (Option H25: 5 dB steps)
• Local oscillator input range: 3.0 GHz to 6.6 GHz (internal mixing uses 3.6 GHz to 6.5 GHz)
• Input coupling: AC and DC coupled
• Module configuration: Single-slot width
– Key Features
• LO input via SMA connector for frequency sweeping
• Low-pass and band-pass filtering eliminates unwanted frequencies and harmonics
• Probe power jack supplies external accessories such as preamplifiers
• Integrated leveling amplifier maintains consistent signal levels
• Direct integration with HP 70000 series mainframes via MSIB and GPIB interfaces
– Typical Applications
• RF signal analysis from DC to microwave frequencies
• Modular spectrum analysis systems requiring variable frequency coverage
• Multi-module measurement configurations leveraging mainframe architecture
– Compatibility & Integration
The 70904A operates within HP 70000 series mainframes including the HP 70001A and HP 70004A. It coordinates with dedicated local oscillator modules and other HP 70000 series components through the Modular System Interface Bus and GPIB.
