By Colin Chidgey G3YHV & David Slatter G0CJG

In early 2021 the design of the SARC WSPR TX Mk2 commenced after a quick requirements gathering and a “wish list” from club members.   The hardware has been redeveloped by Colin G3YHV who created the first version of the TX. The software has jointly been developed by Colin and Dave G0CJG.  The software now supports Type 1 and Type 2 message formats and controlled by a user setting.

Finished Board
Finished Board

Detailed below are the features of the Mk2 version of the project and differences from the original TX.

  • PCB – move to commercial production
  • Display – upgrade from 16×2 character display to monochrome OLED SSD1306 i2c module
  • Time – replaced UBLOX GPS module with DS3231 real-time clock battery backed module
  • DDS – AD9850 retained due to frequency range
  • PA – upgrade from single transistor to new PA design
  • Power Output – 3 power settings up to 100mW 
  • PIC Chip – 18F1320 8k + 8Mhz oscillator to 18F26K22 64k + 64Mhz oscillator
  • Bands – 80-10 including WARC bands
  • Software – major change from a user pre-programmed configuration to user defined Setup and User menus where all key parameters can be changed/set
    • Callsign
    • Locator
    • Clock (need only be set once unless battery replaced)
    • Single/3 band hopping
    • Output Power 0-23dBm
    • Tune up mode (TX for 45 seconds)
    • Set TX % on time
    • Set Band
    • Set Screenmode (invert display and change brightness)
    • Calibrate DDS
    • Calibrate TX Drive levels
    • Reset NVRAM settings
Overhead View of installed board
Overhead View of installed board
Simple Front Panel
Simple Front Panel
Power & Antenna Connections on rear
Power & Antenna Connections on rear

Click here for more information about WSPR

This attachment is a presentation given by Dave G0CJG at SARC on 1/10/2021 about modifications and enhancements he has made to the basic kit. Some of the software updates may be made available but this will require more work to advise on how to connect the additional hardware.

A new updated version with a LCD colour display and software is currently being developed for 2023.