Tag: KG4RUL

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Adding SOTABEAMS variable bandwidth filter to your uBITX

SOTABEAMS make a  Digital Variable Audio Filter Module  that could usefully be added to your uBITx.

Dennis KG4RUL has developed an Arduino sketch for the SOTAEAMS Vari-filter which includes a nice display.  It utilizes a USB Nano V3.0 ATmega328 16M 5V Micro-controller CH340G board, or similar, available from Amazon and other sources and an OLED display module such as the HiLetgo 1.3″ IIC I2C Serial 128×64 SSH1106 OLED LCD Display LCD Module for Arduino AVR PIC, or similar.
Dennis is happy to share his firmware, but cannot offer any support – so please do not contact him for support.
You can download the sketch and a schematic, in PDF, from the SOTABEAMS website:
An additional document supplies information for linking a microcontroller with a SOTABEAMS, VariBeam (VB) module for use with a BITX/uBITX.  You can access this file at the following URL:

Reference
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Off the deep end …

Dennis KG4RUL has gone off the deep end with his µBITX.  His current configuration, basically a rats nest on the bench, comprises:

  • Main CPU (Teensy 3.5) – handling the SI5351 control (I2C), the 20×4 LCD Display (I2c), input from the front panel controller (I2C), control of an AF DSP (I2C), control of a CW Keyer (I2C), monitoring of an SWR bridge, control of an RF Digital Attenuator (SPI)
  • Front Panel Controller (Pro-Mini) – interfaces with a rotary encoder w/switch and seventeen push buttons
  • AF DSP (Teensy 3.5) – implementing Low Pass, High Pass, Band Pass, Notch Filter and pass-through
  • CW Keyer (Pro-Mini)
  • SWR Bridge for tuning and power monitoring
  • RF Digital Attenuator from SV1AFN used to adjust drive power to PA for tuning and adjusting power by band to keep the power output more consistent

This is Dennis’ front panel design: