Lex PH2LB wrote to uBITx.net 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 : https://github.com/ph2lb/ubitx4
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: