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

The new Arduino firmware and the schematic can be found here:

The direct link to the schematic is here:

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.

Toroid winding hints

Mark N7EKU/VE3 has  found the calculator on to be very accurate — so much that he rarely measure after winding anymore. 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).


Ashar talks about the BITx world

There is a long segment interviewing Ashhar Farhan, inventor of the uBITx (and in fact the whole BITx series of radios). He talks about the release of the v5 board, future plans, etc. Ashhar notes that around 20,000 boards have been manufactured to date!  He is also planning to bring out an antenna analyzer kit with a number of additional features.

Reference has been out of action

Regular visitors will have observed that has been out of action. The gap started with a vacation, and a quiet spell over Christmas and New Year. However, Mike ZL1AXG has had some health issues. Posting will commence again now, but it will take a while to catch up!

CW Zero Beat Kit

David  N8DAH has been working on a few projects.    The first of these is a CW Zero Beat

If anybody is interested in a CW Zero Beat addition to their µBITx, then he  has nine in kit form and one built for testing available.   The kits are US$13 shipped inside the US.  Add actual shipping costs outside Continental USA. He can build them for you for $2 extra or only solder the surface mount and allow you to build your own.

J1- Power in 9-12V

RV1- Audio in adjustment

J2- Audio in

RV2- Center Freq Adjustment

Questions please e-mail David direct

David is also working on a new digital controlled audio level project (AGC) and hope to have more info soon but this is still only in the prototype stage.

David’s website is:


Further information about fixes for Harmonics, Spurs and IMD

Removing spurs

Raj VU2ZAP has confirmed that surface mount components can be used in the LPF after the 45MHz filter.

He used SMD Yellow shielded inductors 331nH  x 2 + 51pf to ground.

Summary of recommended fixes to address unintended spectrum products

  1. Replace K1, K2 and K3 with Axicom 12v relays (low current models are fine) to remove harmonics to acceptable levels in most rigs on most bands.
  2.  Install a 45MHz filter across TP13 (v3 board).   Ashhar Farhan VU2ESE inserts a 0.3µH inductor in series with a 10 pf capacitor across TP13 on the v4 board.   This is on the output of the 45 MHz IF amp going to the front end of the mixer.   The inductor comprises 8 turns on a T30-6 toroid (to give 0.3µH or 300nH).   Or use Raj’s alternative as above.
  3. Consider also changing out L5 and L7 with shielded surface mount inductors (yellow type).  See this article.


G4USI Go Box

Several constructors have put their µBITx in a Go Box for portable/emergency use, but this is one of the best looking results yet.

Daimon G4USI has used a 3D printer to produce a very professional looking front panel.

This is a re-mix of DU2RK’s uBitx Case, and the re-worked front panel of this case by AngelDMercedes.

Daimon wanted a different case, one he could build into an existing flight case to create a Go-Box for HF.   He remixed the ideas above to create a case which fitted his flight case perfectly, but with every control and function sitting on the top panel.

In the strictest sense this is not a full case. It is a top and two vented sides. There is not a bottom, front or back panel –  the flight case provides the structure.

On the top photo you can see a 12v 5a power supply and mic in the space to the left of the rig.  Daimon now has a home-brew EFHW multi-band antenna, SOTA Beams ATU and miscellaneous portable QRP operating items in the right hand compartment.   Everything, in fact, that he needs for portable QRP HF.