BitX 40 Build

Some members of AJARC  started a BitX 40 build group in early January 2018

All Builders – Please visit  and look at mods you may like to install in your build.  I recommend the Ver 2 firmware as it has a lot of features with mods.  There are other websites on the internet with other mods and hacks. If you wish to install any of those, please start planning. Be aware that most will require editing the Arduino code.

Notice:  A new version called uBITX or now called MBITX (Micro Bitx) was released on 12-9-2017.  This is a 80-10 meter 10 watt transceiver sold in the same format as the Bitx40.   I have one and have started assembling it into a case.   The UBITX is so newly released there are very few mods available for it at this time.

The uBitx board is $129 shipped slow boat (about 3-4 weeks) with expedited ( a few days) shipping for $10 more via DHL.    As of Feb 2019, a Ver 5 board has been released.  All earlier versions of the boards required extensive modifications to improve spurious emission issues.  Power output on all previous versions of boards was abysmal, dropping to only a watt or two on 10 meters.  At this time I would recommend not buying a UBITX unless you are an experimenter and prepared to try many of the fixes that keep coming up for the boards to address the problems.

The $59 Bitx 40 monoband 40 meter board is still available and shipping right away.  Expedited shipping via DHL is available for $10 more.  I highly recommend this board over the Ubitx at this time for someone to build assemble their first radio.

You can purchase either board at

India Post delivery is about 3-4 weeks and once it goes in the mailbag, it disappears until it shows up on your doorstep.  Just be patient, it does show up.  If you want it in a few days, pay the $10 and add the expedited DHL shipping.   InKits (the case supplier) only offers shipping via India Post so expect the 3-4 week wait on that order.

If you are not interested in making your own case there are cases available at Inkits. There are several case styles and colors available for the Bitx40V3.   Universal cases for the new Ubitx are being offered. If cases are not in stock, keep watching as they restock on a regular basis. You can view cases at

Due to complexities of making a case, our group will not be concentrating on DIY cases and will be more concentrated on assembling the boards into a manufactured case reminiscent of the Heathkit days.

If you are placing an order for a case I would recommend buying the $8 AGC printed circuit board from Inkits.  I no longer have any parts sets available for the AGC board.

As of Feb 10th most of the builders have finished or nearing completion.  I anticipate our sessions will be over sometime in early March.

If the web contact form is not working for you get my email address from QRZ.  Everyone is welcome to drop by and see what we are doing on the days we have our builds.

Bob N4FV

Bitx40 Builder Notes:

We install a 100 pf capacitor across L30 to comply with 2nd harmonic suppression requirements.

We install (2) 1N4148 diodes across the input to Q13.

We have found installing a 1000 uf 25 volt cap on the input of the Radiuno 7805 volt regulator and a 100 uf 25 volt on the output  along with replacing the 2 wires that feed the DDS signal from the Raduino to the Bitx40 with RG174 seems to tame the worst tuning click problems.

If you are told your Bitx40 has distorted audio or it has residual carrier, the carrier oscillator is off frequency.  There are 2 ways to correct this.

#1 – Install a trimmer capacitor that was omitted from the board. A SMD capacitor may have to be swapped for one of a smaller value.

#2 – Disable the on board carrier oscillator by removing 3 SMD parts, install a RG174 cable from an unused CLK pin on the Radiuno and load the V2.X sketch from

#2 is actually the better alternative as the only part required is a 6 inch length of RG174.  Most of the Bitx40’s we assembled required this modification.

Other links of interest about the Bitx 40 and uBitx  This is the goto place for all things BITX.  I recommend subscribing to the digest version otherwise you will constantly receive emails if you elect to receive email updates.

AGC Board  info is located at  This board also provides an S meter circuit.  I have provided an amazon link below for a compatible CB radio replacement S meter.

AGC board connection labeled as IF-1 is located on the top side Bitx40 circuit board between R23 and R24 on the trace that connects those SMD parts to the Base of Q2.

AGC board connection labeled as IF-1 is located on the top side of the uBitx circuit board between R30 and R31 on the trace that connects those SMD parts to the Base of Q30.

An inexpensive soldering station for those on a budget.

A CB S meter that works with the Inkits AGC board.