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:

Reasonable heat output and the raduino regulator



Bob W4GHV asks how hot the regulator on the Raduino should get.

The Raduino has a 7805 regulator sticking awkwardly out of the side of the Raduino board.  Unsoldering the 7805 regulator and mounting it   on the reverse side of the board (facing inwards) can fix that little awkwardness.

The regulator also has another problem.  It gets hot!  It is fed with 12v DC input from the rig and produces regulated +5V for the Arduino Nano and the 16×2 Display unit.   The display itself draws up to 100mA.  The Nano typically draws around 35-70 mA, but it depends on exactly  what is connected.   The voltage difference between the input and output multiplied by the current is power dissipated in heat in watts (i.e. typically a bit over 1 watt).

The 7805 regulator can feel quite hot to the touch.   However, there is really no danger that it will get overheated at 12 to 13.8v input voltage and typical current draws from the Raduino unit.  Allison KB1GMX says however, “Keep it under 70C (168F) as the device has a thermal shutdown and it lives longer”.

You can share the heat around by installing a resistor between the 12vDC line and the 7805 regulator input. Skip, NC9O, added a 47 ohm resistor in the 12vdc into the regulator by cutting the trace from pin 15&16 on the Raduino. He used a  1/4 watt resistor, but calculations by others suggest a 1/2 watt or 1 watt resistor would be better.

The alternative is to remove the regulator altogether and feed the Raduino from a suitable 12v to 5v buck power supply (obtainable off eBay or Aliexpress for very little outlay) or set the output of the buck power supply to just over 7v if you can’t be bothered removing the 7805.    For those of us thinking about touch screens, this makes quite a bit of sense!


Biteensio production boards have arrived and available now

Jim  W0EB has announced that the Biteensio production boards have arrived and been checked out.  See for details on how you can order one of these.   Remember that Vince K8ZW was the winner of the competition to name these boards.

Jim also has some breakout boards for the 1/8″ jacks that will allow them to be easily mounted and wired up without having to guess which terminal does what.  These may save a lot of grief.

Key features of this board include:

  1. uses the PJRC Teensy 3.6 as the MPU rather than the Arduino NANO
  2. plugs into the 16 pin female header on the uBITX main board just like the Raduino and the RadI2Cino
  3. the main tuning encoder, function switch and push-to-talk wiring will still be compatible with both the Raduino and the RadI2Cino.
  4. All of the extra, available I/O pins are brought out to DuPont pin headers (some on the front and some on the back of the board)  

See the board installed on the µBITx main board below:


Prices are $12 (USD) for the bare boards to domestic US customers and $16 (USD) to international customers.

Kits which will include all parts except a Teensy 3.6 MPU, will be US$35 to US customers and US$45 to international customers. This price includes shipping (both domestic and international).

PayPal will be the preferred payment method and the ONLY payment method for international customers.

Download a copy of the BITeensio Board Construction Manual. Up to date versions will always be available in the “Documentation” directory under the W0EB/W2CTX uBITX Files link on this page.

For other details see the W0EB website.

Note that the Biteensio is not compatible with the manufacturer’s firmware supplied with your µBITx or the CEC firmware from Ian KD8CEC. The Biteensio board uses a different keying system and a different processor (Teensy 3.5 or 3.6), so you will need to use the W0EB/W2CTX firmware supplied especially for the Biteensio.


Quadrature output from si5351a

The SI5351a is a key secret to the success of the BITx range of transceivers.  This chip puts out three PLL signals for the two local oscillators and the VFO in the µBITx.   Without this chip (or something similar) a double superhet design such as that used in the µBITx would require considerably more complexity, with either an analogue VFO that was prone to drift (as in the BITX20) or a PLL circuit that added cost and complexity.  The Raduino integrates a 16×2 line display along with an arduino nano and the SI5351a chip … prebuilt for US$25.

So along comes Miguel PY2OHH who announces that he as designed a new
VFO using the SI5351 and Arduino nano, which produces an output  “in quadrature” from 4.76 MHz to 220MHz.  This means is has two outputs on the same frequency, but which are 90 degrees phase shifted from each other.    Note that there is also a small frequency window that can’t be used between 144.66 MHz and 150MHz.

You can read all about the idea, and see a prototype VFO here.

So why is this such a big deal?

What you may not know is that a quadrature mixer, which requires two signals from a local oscillator fed at 90 degrees from each other, is at the core of most SDR receivers.   In an SDR receiver, there is very little “front end” analogue circuitry, with signals rapidly routed to a processor in digital form to apply filtering and band-limiting.    Miguel’s breakthrough paves the way for simple, low-cost SDR transceivers that are of low cost and high performance.   We know that Ashhar Farhan VU2ESE has said in the past that he is experimenting with SDR designs (and with a VHF/UHF version of the BITx).   Let’s hope this innovation spurs him on to produce a stunning new SDR design in kit form!


Raduino versions

Kees K5BCQ is trying to assemble a list of Raduino alternatives.  Here’s the modified version of his list that is not a mashup of hardware and firmware variations (which is a much longer list!), but simply a list of Raduino hardware options:

1) Original “Raduino” with a Nano Ver ? (base Farahan started with and probably what most uBITX units have today)
2) “RaduinoUMAX” with firmware by Mike Hagen, WA6ISP, (more I/O)
3) “Raduino Protoneer” (Arduino Zero Compatible Nano-ARM, uses SAM21 microcontroller)
4) Raduinoi2c Board from Nik VK4PLN (see
5) “Raduino Pill” by Joe, W3JDR (uses a STM32F103 “Blue Pill” microcontroller, lots more I/O)
6) “BITeensio”, this is the new one by Jim Shelton, W0EB, more info coming soon.
7) “JackAl” board  by Jack W8TEE, and Al  AC8GY – Teensy 3.6  (`$50).
8) “KB1OIQ” by KB1OIQ has I2C display, supports Keypad and voice output suitable for low/no vision operators. ??$$
9) “Alison TBD” by Alison, KB1GMX, uses the Nano and has no rotary encoder, less or no menu, more buttons. ??$$


Arduino Nano test analogue inputs

John VK2ETA has produced a small piece of diagnostic firmware intended to be used by constructors to test out the Raduino.

The objective is to help original kit builders identify issues (e.g. wiring or “not working” problems), but also for more advanced experimenters both during construction and after “oops moments”.

So far it only tests the I2C bus, the communication with the SI5351 and the analogue inputs of the Raduino in a graphical form.

The plan is to expand to the audio circuit, the receiver chain, the TX low pass filters’ relays and hopefully more.

This is where be needs the input of other constructors to determine what to test for in the first instance and then some ideas to make the test results as simple but still useful to more advanced users.

John is looking for feedback as to what issues you had when building the kit that could potentially be incorporated in the diagnostic software.  Tests need not be Arduino-only tests. Operator ‘s interpretation, as in “Do you hear the tone in the speaker, Y/N” are quite ok.

John has uploaded a beta version of the software  to the IO Groups Files area:

Basic instructions are in the README.MD file in the top directory.

The main menu number 2 (Analogue inputs), brings a second level menu for testing the encoder inputs, the push button, the PTT, the Keyer and the spare analogue input.

Results are displayed in a horizontal bar graph with a scale from 0 to 5V representing the value read by the inputs. That way you can see how it matches the values your voltmeter indicates on the respective pin.

Results are shown only on changes to the values read, for example when rotating the encoder, pushing the PTT or the encoder push-button etc…

If no results are shown then your Arduino cannot read analogue inputs and it would mean plan-B:  replacement of your Raduino.


Second lot of Radi2cino boards available to purchase

Jim Sheldon, W0EB has announced that the W0EB/W2CTX/N5IB “RadI2Cino” (pronounced rad ee too CEE no) I2C replacement for the Micro BITX (uBITX) Raduino card is again available for purchase.

NOTE: these are only for the uBITX, not the BITX40 and other earlier models.

This board is designed to utilize either a 2 x 16 or 4 x 20 I2C LCD Display (not included) instead of the parallel display originally included with the uBITX so that the digital I/O lines formerly used by the display can be used to run the CW keyer and a few other functions in a much more efficient manner.

Prices have lowered a little since the first offering.

Partial kits with the IC’s soldered in place are no longer being offered.

Current options are:

  1. Bare Board (you supply the parts & you build it). $10 US shipping included. . International $15 US shipped.
  2. Complete Kit of Parts (less the Arduino NANO, LCD display and display I2C controller) – you build it. (All parts except the NANO, display and display controller are included in the kit.) $30 US shipping included.   International, $45 US shipped. All customs duties and VAT will be the responsibility of the purchaser.
  3. Completely assembled and tested RadI2Cino Including the Arduino NANO but less the display and I2C display controller.Assembled and tested RadI2Cino boards will be available by Special Order Only. They will require up-front payment by PayPal and up to a 1 week lead time to build and properly test) $75, shipping included in the U.S.

    No international orders will be accepted for assembled and tested boards at this time.

All orders will receive the complete assembly manual which includes a full bill of materials, full board layout diagrams and full schematics in PDF form via email.  This manual has also been attached here for your download:  RadI2CinoBoardConstruction. You can read through it and decide if it’s something you’d like to build.  The same manual will be included with the order by Email.

The bill of materials, included in the manual, has ordering information for the parts. Parts suppliers are Tayda, Digi-Key and Mouser.

Please, don’t post orders or info requests on the BITX20 list as Jim doesn’t always get the posts from the reflector.

Email w0eb (at) cox dot net for ordering or further information.

RaduinoUmax shipping

Mike, WA6ISP, is shipping the first of his new Ubit RaduinoUMax Raduino replacements  today.

Mike says he has been working like a beaver since the PCBs arrived.

The MAX is for the 16 Added I/O pins on the end of the PCB.   It makes the PCB a little longer, but still fits into uBitx Radio PCB.   I2C control gives you 16 more 5V digital I/O ports and uses an Adafruit Library for simple control.   Three I2C address jumpers are provided so you can use other I2C modules.

Reference 1
Reference 2