CEC beta release for v5 board


Ian KD8CEC has announced a beta version of his firmware (Version 1.12) for the uBITX V5 board.  He has written an article about it here.

All existing firmware functions for V3 and V4 are available on the V5 beta.

The same version of uBITX Manager will work with the v5 Board.

Only the LPF control and the frequency control part are changed in the V5 code.  Ian has released firmware V1.121 for V5.


Identifying your uBITx board

Alison KB1GMX counts 5 different schematics for the µBITx, and that is not including the HF1 or minima (2014) designs that came before the µBITx.  The design was evolutionary.

The first production boards were labelled “V3”.  Two further iterations have been sold since, the “V4” and now “V5”.

  • V1 and V2 models were prototypes, and were not marketed and sold
  • V3 had the TDA2822 audio chip in it.  One batch had issues, and would easily fail.  This was the first production board from December 2017.
  • V4 had discrete transistors for the audio section and test points were introduced in a number of locations on the board.  Pads were also included to allow the RD16HHF to be used to replace the, as shipped,  IRF510 finals.  This board had issues with low audio output – more suitable for headphones than speakers.
  • V5 changes the 12mhz IF local oscillator to 11.059 MHz, and uses the LM386 for audio.   The Low Pass Filter layout and relay arrangement has been improved to reduce harmonic removal.

V3 and V4 are probably technically not fully compliant with emissions regulations in most countries (at least in the developed world).   However, the low power output of the µBITx probably means that emissions will have resulted in few issues with interference in practice.

The effectiveness of harmonics, IMD and spur modifications incorporated in the V5 board have yet to be established across a selection of production boards.  There are no doubt improvements, but the degree to which the product could be considered to be 100% compliant on all bands and all modes has yet to be established.

[Edited by uBITx.net]



Spectrum analyser tests of v5 uBITx board

Jim Sheldon W0EB has done some initial testing of the new µBITx board on his brand new spectrum analyser.   The results are CW only (so these results won’t show the impacts of any distortion in the mixers or IF bidi amplifiers that were observed with the v3 and v4 boards.

There are still some bands that would not meet most countries’ spectral purity requirements.

For a full set of graphs for each band click on the reference link below.


History of designs leading to the v5 uBITx

The following list of circuit designs has been compiled by Tom KF5NWC:


A large group of enthusiasts worked with Farhan to create and test a general coverage receiver and multi-band transmitter called the Minima. Its simplicity, innovations such as its KISS mixer,  shuttle tuning using a potentiometer, and overall low build cost inspired hope of an affordable multi-band transceiver (to me anyways). 🙂

link to schematic

Ubitx v1

Continuing on with the general receiver concept with lessons learned from the minima, the uBitx was published.

link to schematic

uBitx v2

No schematics are known to have been published.

uBitx v3

The version 3 schematic is the version of the first production board from HFSignals.com (formally hfsigs.com).

link to download

uBitx v4

link to schematic on HFSignals

  • c210 and c216 – are listed as 0 pf and are not present on the board used in production by HFSignals.
  • Q942 and Q952 – are not populated on board sold by HFSignals. As sold by HFSignals, the final drivers for the PA are IRF510. These alternative pads allow experimentation such as replacing the IRF510’s RD15HVF1’s which are a different pinout.

uBitx v5

link to download

  • c210 and c216 – are listed as 0 pf and are not present on the board used in production by HFSignals.
  • Q942 and Q952 – are not populated on board sold by HFSignals. As sold by HFSignals, the final drivers for the PA are IRF510. These alternative pads allow experimentation such as replacing the IRF510’s RD15HVF1’s which are a different pinout.


For those who are not following the email list, during the gap in coverage on ubitx.net in January, Al and Jack launched their JackAl board that adds a lot of features to the µBITx.

The hardware is compatible with the µBITx v5 board, but requires different firmware.   More details on JackAl will be added to the website with a January posting date shortly.  Check back in the list of posts, as I am backdating information to provide a better history for constructors visiting the site.

Jack is going to be at Hamcation in Orlando. If you see a shirt with the picture of the JackAl display on the back at Hamcation,  then stop and say “Hi!” to Jack W8TEE.

Reference 1
Reference 2

BITeensio card beta firmware released

Jim Sheldon W0EB has announced that the Triumvirate Skonk Worx (TSW) has published their latest “beta” 2.8″ or 3.2″ Color TFT touch screen firmware for the BITeensio controller card. This new firmware addresses the changes Farhan made to the uBITX in the release of his Version 5 transceiver board.  This board is now shipping from HF Signals.

Using the BITeensio card in combination with the new firmware means constructors will now have the capability of selecting operation with either the older V3 and V4 uBITX boards which we are calling “Legacy” boards or the new Version 5 ones via an item in the “Calibration” menu.

Depending on which type of uBITX it is installed in, the  one time calibration will be required for that uBITX board.

Calibration data is stored on the BITeensio’s Micro SD card in different locations for the 2 different versions so if you calibrate the card in a V4 (or V3) radio, and later decide to switch it to a V5 radio, you will have to again calibrate it for the V5 system. However, once that has been done, you can then swap the BITeensio back into your original “Legacy” radio, select “VL” in the calibration menu and it will recall the previously stored calibration data for that version. If it’s the same VL board you originally used for “VL” calibration, you should not have to re-calibrate the card. If, however, you install it in a different uBITX than the original one, you may have to touch up the calibration to make things sound right and operate on the right frequency.  The same is true for V5 boards.

Since both of the displays (2.8″ and 3.2″) use the same ILI-9341 controller, and have the same number of pixels, no software changes are needed to change out the display. No user action is required to switch from one to the other except to make sure they are cabled properly and this is outlined in the manual.

The operating manual for this software has been completely re-written to reflect the changes and the pictures have been changed to show the operating information in the new version.

You can find complete information on this (and other items from TSW) on their website.


Antuino kitset coming

Ashhar Farhan has foreshadowed his upcoming Antuino design.  This is a modern replacement to the Sweeperino he designed much earlier on.  The Antuino uses an arduino nano and an si5351a (both can be found in the µBITx) and the crucial RF part – an AD8307.

Details can be found here:


V5 uBITx board in production

Ashhar Farhar reported on 6 February 2019 that HF Signals has pushed the uBITx v5 into production. An initial 100 boards had arrived so they may run out quickly (reminding us of the v3 board shortages of 2018).

Note that  HF Signals website has not yet been updated.

See the scans on https://groups.io/g/BITX20/album?id=84174.

The new Arduino firmware and the schematic can be found here:  https://github.com/afarhan/ubitx_v5/.

The direct link to the schematic is here:  https://github.com/afarhan/ubitx_v5/blob/master/ubitx_v5.pdf

The new firmware breaks backward compatibility with the previous firmware as the Intermediate Frequency is now 11.059 MHz and the relay switching is different.  Probably, is it is possible to patch the new code to switch between the two LPF relay switching schemes as well as the IF with some #define statements.

The new ‘features’ are :

  • The LM386 is back as the audio amplifier (like in the BITx40. All hail the cross-over distortion sickness!
  • The IF is now 11.059 MHz.   These 68pF crystals are easily available, with a pretty good 2.7 KHz band pass. As their frequency is away from any spur of 16 MHz and 25 MHz (the two crystal oscillators on the Raduino) there will be no spurs.
  • The relay switching scheme is different. The 30 MHz LPF is now always on, the individual LPFs for lower bands are switched in or bypassed (by default). It is easily understood in the circuit diagram
  • The CW wave-shaper uses a 1 uf capacitor in place of 0.1u, this reduces the key-clicks.
  • The circuit now uses BFR93W in the 45 Mhz IF amps, for more overall gain in the TX lineup.
  • A 470pf in the emitter degeneration of pre-driver instead of a 0.1uf gives more gain at 28 MHz than 3.5 MHz.
Reference #1
Reference #2

Toroid winding hints

Mark N7EKU/VE3 has  found the calculator on toroids.info to be very accurate — so much that he rarely measure after winding anymore. Toroids.info quotes a quite generous length of wire to use (even considering the 1″ leads) so he usually subtracts an inch.

No need to re-wind if you loose count. As long as you have a cell phone or other digital camera, just take a picture and then zoom in on it. It becomes very easy to count if you do that.

How to wind: first put the wire through the center, gather the ends, and pull them taut. Now wind one half of the windings, and then the other. This way you only have to deal with one half the length of wire at a time (instead of threading the entire length through for the beginning turns).