Some great mods from PH2LB


Lex PH2LB  wrote to to tell us about a page on his website where he describes his uBitx (V3) mods.   This is a very nice build, and he has some good ideas.   Check his page out here

In particular Lex has developed some custom firmware that firmware geeks may be quite interested in …

“Second mod : custom firmware”

Originally based on the v2 software but merged to v4.3 and updated to code to have a lower RAM footprint (usage of F(…) macro and strcpy_P) with about 50%.

Source files can be found here :

Over the last few months there have been a range of ideas to boost mic drive output or to add compression.  Here’s a mod designed to work with a dynamic microphone …

“Fourth mod : dynamic microphone amplifier.”

Because I like to work with dynamic microphones, I added a dynamic microphone amplifier based on the microphone preamp designed by Javier Solans Badia, EA3GCY for his ILER transceivers.

There are a whole bunch of ways to add buttons. KD8CEC does this through paralleling up buttons with different series resistor values on the encoder analogue port).   Lex has taken a different approach that will be of interest to some constructors.   He uses a PCF8574 I2C encoder (like the backpacks for a 16×2 or 20×4 LCD display) and uses the existing I2C bus…

“Fifth mod : again adding extra buttons.”

Using a PCF8574AP I2C IO Extender and hooked it up to the all-ready existing I2C bus on the Raduino for more direct menu buttons. Needs the custom firmware to direct switch between bands with a PA bandplan limitation (also has FULL option) and Step size up and down.


Something that a number of constructors have done is to remove the 7805  and supply 5v to the Raduio using a separate 5v supply.  Most are using buck or buck boost modules, but Lex has used a P-MOSFET.   There’s a good description of his approach on his website …

“Sixth mod : removing 7805 from Raduino and reverse power protection.”

Relocating the 7805 is a good idea, but adding a reversed voltage polarity to a uBitx is a must. I used a P-MOSFETs for that (also link to good video about using P-MOSFETS for reverse power protection).

Finally, you may be interested in Lex’s use of the Manhattan style technique for PCB layout.  It can look very professional as per this example:

An amazingly smart idea for extra I/O ports

Tom WB6B want to expand the number of digital and analog I/O pins available to him in adding enhancements to his uBITx.

He came up with an ingenious idea, by creating a Smart LCD Backpack to replace the commonly found ones on inexpensive 2×16 and 4×20 I2C displays found on eBay and Amazon.

He has uploaded a library to GitHub that allows you to program a Arduino Nano to emulate the common I2C to parallel backpack used on an I2C display (either size). The Smart I2C Backpack, additionally, allows you to read and write the analog and digital pins on the Smart I2C Display Backpack.

The package includes a interface library that you include in your code to interface with the Extended I/O functionally. Also included are two example sketches. One is the code you program into the smart backpack. The other is a demo/test program you program into another arduino and connected via the I2C bus to the Smart Backpack Display.

The Smart Display Backpack should work with firmware using standard I2C LiquidCrystal drivers such as the KD8CEC firmware.

The code uses libraries that are installable from the Arduino library manager,.  The GitHub URLs are just for reference.

The following libraries should be part of the base Arduino software install:

  • Wire
  • LiquidCrystal

Tom hopes that others will enjoy this new display and I/O expander.

And the link to the code …