Marine radio - SRG-3150D/DN - Navis USA LLC - for ships / MF / HF
Radio frequency Definition & Meaning - Merriam-Webster
MF/HF radio - Frequency selection - YouTube
Radio Electromagnetic Spectrum Frequency Bands - RF Cafe
Upgraded TinySA Spectrum Analyzer,Karagas Spectrum Analyzer Handheld,MF/HF/ VHF Input for 0.1MHZ-350MHZ and UHF Input for 240MHZ-960MHZ,Portable Frequency Analyzer with 2.8 Inch Touch Screen V0.3.1: Amazon.com: Industrial & Scientific