Three mode options: ISB, USB, CW. These modes provide flexible signal interfaces to suit different setups and testing needs. Frequency control and range: 0 to 55 MHz continuous adjustment with 1 Hz step resolution for precise tuning across the entire range. Band mapping: Six frequency bands corresponding to bands 1 through 6: Band 1: 3.8 MHz Band 2: 7 MHz Band 3: 9 MHz Band 4: 14 MHz Band 5: 18 or 21 MHz Band 6: 27 or 29 MHz Power input and usage caution: Input voltage of 12 V is for short time testing only. Prolonged use at 12 V can cause heat buildup on the board. Key benefits and practical value: Flexible operation with three selectable modes to fit different test setups. Extremely fine and broad frequency control across the 055 MHz range for accurate signal generation or testing. Clear band division with six selectable bands simplifies quick switching between common HF frequencies. The 12 V input option is available for quick short tests, with a clear caution to avoid continuous use that could heat the board. 23 use scenarios: Field testing for amateur radio or RF experiments requiring quick stepping across frequencies up to 55 MHz using CW, USB, or ISB modes. Bench RF testing where precise 1 Hz frequency steps are needed to characterize circuits or perform calibration across the six frequency bands. Educational or hobby projects that involve practicing signal generation and tuning across multiple HF bands with selectable modes for different learning scenarios. Note on compatibility and performance: The device supports three operation modes (ISB, USB, CW) and precise 1 Hz step tuning from 0 to 55 MHz, with six defined bands for quick band switching. The 12 V input is intended for short tests only to prevent excessive heat on the board.