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 Tx/Rx/BFO frequencies 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
  • Low pass filters to turn square waves to sine waves
  • 27 MHz crystal

Parts

Blue Pill Card

• Blue Pill Card
• Used right angle headers and Dupont cables
• Replaced BOOT 0,1 jumpers
  • Jumper on BOOT1
  • Switch on BOOT0 - easier to download code

128x32 OLED

• Ebay

Arduino Library for OLED

• U8g2: Library for monochrome displays, version 2

Rotary Encoder/Breakout Board

• Includes pushbutton Switch
• Needs R/C filter on output
• Includes Pull-Up resistors
• Simple Rotary Encoder Arduino library
• Library for the Arduino environment for using a rotary encoder as an input

Si5351 FrequencyGenerator

• 3 outputs
  • Tx
  • Rx
  • BFO

VFO TX

• From 5.9993-5.7493 MHz

VFO RX

• RIT knob is taken in through an A/D and adjusts the frequency plus/minus 1 KHz

BFO

• 8.8314 MHz in receive
• 8.8307 MHz in transmit

Low Pass Filters

• 6 MHz

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

Schematic

Libraries

• VFO and BFO with Si5351A, OLED and Arduino
• U8g2: Library for monochrome displays, version 2
• Si5351 Library for Arduino
• Universal Digital VFO Si570/Si5351
• Adafruit_Si5351
• Si5351 Library for avr-gcc
• vk3hn_VFO_controller
• Simple BFO with si5351 controlled by Arduino

Videos

• Charlie Morris YouTube channel