HW-9 VFO

This is a work in process - Gathering pieces.

Features

• Replace HW-9 internal VFO with a digital VFO
  • HW-9 VFO has legendary issues
    • Mechanical issues with vernier
    • Drift due to thermal
    • Lack of resolution
• Fits within HW-9 VFO Box
• Controls frequency with rotary encoder
  • 10 Hz steps
• DD1306 OLED Display
  • I2C Interface
  • "Curved" display
• Uses RIT control on HW-9
  • +/- 1 KHz RIT
• Blue Pill Microprocessor
  • Arduino compatible
  • 3.3V
• Understands band switch for MHz displayed
• Si5351 Oscillator
  • I2C Interface
  • 3 Outputs
    • Transmit frequency
    • Receiver frequency include offset plus RIT
    • BFO frequency
  • Band pass filters to turn square waves to sine waves
  • 27 MHz crystal

Parts

• Toroid Calculator
  • Kits and Parts dot Com
• A short guide to harmonic filter for QRP transmitter output

Libraries

• U8g2: Library for monochrome displays, version 2
• Si5351 Library for Arduino
• Universal Digital VFO Si570/Si5351

Videos

• Charlie Morris YouTube channel

https://www.youtube.com/watch?v=jRNrPIrgWto Homebrew 80/40m SSB/CW Rig - #5 VFO/BFO and BPFs