The Marconi IFR Aeroflex NAV-401L is a self-contained ramp and bench test set for functional testing and calibration of avionics navigation and communication systems. This FCC Type-Accepted instrument meets electronic functional test requirements for Category I and Category II Instrument Landing System (ILS) operations. It generates signals for Marker (MKR), VHF Omnidirectional Range (VOR), Localizer (LOC), Glide Slope (G/S), and Communication (COMM) systems, making it essential for aviation maintenance, troubleshooting, and certification workflows.
Technical Specifications
Signal Generation
• Frequency ranges: 72–78 MHz, 107–156 MHz, 327–337 MHz, 327–397 MHz
• Crystal (XTAL) and Variable (VAR) frequency modes
• Output range: −7 dBm to −110 dBm
• Maximum output: −7 dBm (0.1 V) on any band
• Phase-locking: 25 kHz intervals (MKR, VOR, LOC, COMM); 50 kHz intervals (G/S)
• Separate internal localizer transmitter: −18 dBm output for simultaneous LOC/G/S radiation in G/S XTAL mode
VOR System Testing
• Bearing selection: 0.1-degree steps
• Bearing accuracy: ±0.1 degree
• Built-in 90-degree bearing monitor
• 90 Hz and 150 Hz tones: phase-locked with 0.1-degree accuracy; relative phase variation in 5-degree steps
• Front-panel LOC and G/S centering calibration
Modulation
• MKR: 95% modulation ±5%
• VOR, LOC, COMM: 30% modulation ±2%
• G/S: 40% (±2%) or 30% (±2%) modulation levels
• NAV tones digitally derived from 2.16 MHz crystal oscillator
• Tone frequencies: 1020, 400, 1300, 3000 Hz at ±1% accuracy
• Built-in modulation monitors: 0–30% and 0–100% ranges
COMM System & Frequency Counter
• Integrated RF power meter: 0–10 W and 0–100 W ranges
• Peak or average power measurement for COMM transmitter modulation checks
• Built-in frequency counter: displays generator and COMM transmitter frequency; measures external frequencies 1 MHz to 300 MHz at 0 dBm
– Typical Applications
Airborne and ground-based avionics system functional verification; Category I and II ILS certification; navigation and communication receiver calibration; maintenance troubleshooting on production and service lines.
