Getting prepared for the JackAl

Some of you are waiting with baited breath for the JackAl Board, announced by Jack W8TEE.   You can get yourself geared up for the JackAl by pre-purchasing some of the kit required, as it is due to be released shortly.  You will need a colour touch display panel, a Teensy 3.6 processor and associated Teensy audio board.

Display panel

There are two display options for the JackAl board: 5″ or 7″.  Neither is likely to fit in your existing µBITx enclosure, so you may also want to purchase a new enclosure.

The panels can be purchased from Their order numbers are:

ER-TFTM050-3 (5″)
ER-TFTM070-5 (7″)

Both displays use the following options:

4-wire SPI interface
Resistive touch
No font (the library is being used for fonts)

Both are 800×480 displays using the RA8875 chip. If you run the samples using a touch screen, make sure you run the Calibration sample program first.

Teensy 3.6 and audio board

The Teensy 3.6 and its associated audio board can be purchased from the manufacturer’s website or from other sources.


MicroSD reader extender

Rohn KR0HN  was “parts shopping” online when he came across a microSD card extension cable.

This could be used to extend the microSD card slot of the Nextion display out to the exterior of the case.  This would be handy for upgrades to the display firmware as new features become available for your display.

The link to the amazon page is:


Dimming your Nextion display

Ian KD8CEC has been looking at power consumption on the Nextion display and how to effectively dim the screen for portable µBITx work, where you want low current drain.

The following picture show’s Ian’s display (2.8″ TJC Chinese version) at Full Power:

And the screen fed with a series 50 ohm resistor (1/2 watt rated or more):

The slightly dimmer display halves the current consumption from 89mA to 44mA with a series 50 ohm resistor (made up of two 100 ohm resistors in parallel (or 3 x 150 ohm resistors in parallel).  The Nextion screen has a built in software dimming function, and this can be adjusted in Ian’s Nextion display firmware.   However, the feature generates noise in the µBITx and is not recommended.

Resistor installation

Installing a series resistor (with a value between 20 ohms and 100 ohms) in the +5V power lead will cause the display to be dimmed, but function normally (except for use of the micro-SD card reader).  The resistor could be installed across a slide switch or toggle switch (with one pole shorted and the other going through the resistor) to allow for two settings (normal, dimmed).   This could be handy for night time or portable use.  The circuit diagram for this is as below:

For further details see Ian’s website.

Breadboard uBITx

Jon Titus  KZ1G  shows off his breadboard construction  technique, which he uses while his rig is under development.  The board is mounted on a piece of plywood and usea 1/8-inch clear plastic as front and rear panels for controls and connectors. This “breadboard” technique has been used by Jon for other projects, because it lets him rearrange control locations, ensure clearances between components, jacks, heatsinks, etc.  In this way he doesn’t ruin a nice front panel when later adding an extra pushbutton or switch, etc.

After learning about the W0EB and N5IB RadI2Cino (Rad I2C ino) project he needed more room for the replacement board and a larger LCD. A section of plywood was glued on the front (see photo) and the front panel  was then able to be moved forward by about 4 cm.   Jon quickly added an extra pushbutton, and drilled holes to mount the LCD.

However, when do you make the call to put the whole thing in a proper metal case Jon?


Evening up power out using KB1GMX and K9HZ solutions

Mike N6CMY has been doing some mods on his µBITx, including some of Allison’s mods by substituting 2n2222’s and a BFR106 for the 3904’s on the RF lineup (pre-driver and driver stages).

In terms of output power the results are impressive. But in terms of levelling  up the output… well not so good.

Mike measured 12W on 10M and over 35W  on 40M!  He was a bit taken aback at this point!

He finally bit the bullet and used K9HZ’s multi relay/pot method for levelling the response.

Mike was reluctant to use such a brute-force solution for a subtle problem but he now measures 15W on 80, 40, 20 M and 12 on 10M. VICTORY!!


A fan for your uBITx

Arvo KD9XLC has put one of these 12v fans that cost less than a dollar on the back of his Excelway case from Bangood (which apparently now on sale for $8.88).

You could attach the fan to the cabinet with hot glue, or use the correctly sized bolts/nuts.

And if you don’t want those fans to run on receive connect them to the TX 12v line, namely at pin 3 on U2, which is what Arvo did.


JJ1EPE has had a uBITx article published in Japanese CQ Magazine

Akira Horie JJ1EPE  has had an article published about the µBITx in the 19 June edition of the CQ ham radio magazine of Japan.   

The magazine is of course in Japanese.     Akira’s article covers:

  • A helpful  website ( 
  • Helpful firmware, particularly Ian KD8CEC’s firmware
  • Instructions on how to upload the firmware to the µBitx.
  • How to obtain certification of the µBitx from the relevant Japanese authority.

Gaining certification for a home-built rig is not straight forward in Japan and involves:

  1. Ensuing the µbitx cannot transmit outside of the ham bands approved for use by Japanese amateur operators
  2. Suppression of spurious harmonics to meet Japan regulations, for instance by using an external LPF and/or tuner.

Akira has the all important certification and  license to use his µBitx from the relevant Japanese government authority.

He is now enjoying QSOs on his µBitx!

Adding a keypad to your uBITx

Arv K7HKL asked whether anybody was interested in adding a keypad to their µBITx and got quite a few responses.  It seems that there are a few interested in the same idea!

Jack W8TEE says he would use an analogue approach but this requires lots of spare digital I/O ports that simply don’t exist on a standard µBItx.  So what choices are there on a standard µBITx with just one spare analogue port available (A7) on the raduino board?

The choices are simple, you could use:

  1. An i2c expander port (we’ll ignore this suggestion for now)
  2. A matrix keypad with resistor array fed into the single analogue port on A7 (a bit like how the keying is done on the µBITx)
  3. An i2c keypad.

Matrix keypads with resistor arrays

In terms of matrix keypads there are plenty of choices from simple “rubber” keypads, through to expensive and solid keypads.  With a choice of 12 or 16 keypads, you may want to think about the options carefully.

Some only have numbers, others have blank keys that allow for customisation.  For example, you can replace the blue bits of paper on the  Robotdyn keypad with your own printed symbols or numbers:

The keypad illustrated  above does not require a resistor matrix as it is built in to the module.

i2c keypads

As it happens Robotdyn also make a handy capacitive i2c encoder board that has a matching capacitive keyboard.  If you do decide to use an encoder board with the TTP229 chip on board (like the Robotdyn board below), then you should note that there is a hacked sketch that directly works with the board via any 2 ports using bit-banging, as well as a sketch that uses the Wire (i2c) library.  A useful reference article can be found here.

[ has no interests in Robotdyn!]


Probably the i2c approach would be the preferred approach for most constructors as it does not require using up the last available analogue port on the Raduino.   Constructors generally like to save this port for essential analogue functions like a digital S-meter and Power Meter.  Regardless of which method you use, you will need to leave aside clock cycles to montior keys being depressed.

Both approaches will require some simple coding changes to be made to the  firmware.  We will be waiting to see the firmware release from Arv!

By the way, here at we won’t be installing a keypad. There is a very nice and practical virtual keypad (thanks to Ian KD8CEC) provided for free in his Nextion display code.  A frequency can be easily dialled up or you can switch to another band, right there on the Nextion screen.