The UNOfficial BITX40 FAQ
The Officially Unofficial BITX40 FAQ
All around the web folks are asking questions about the BITX40v3. This is my attempt to answer the most common questions raised. I (Ryan, KC7RYS) am not affiliated with hfsigs.com or anybody who is. I’m just a guy with a keyboard who can’t stand empty space on the screen. I don’t guarantee the answers here to be definitive, permanent, or even completely accurate. If you spot a mistake, leave a comment below and I’ll be glad to fix it.
What is the BITX40?
The BITX40v3 is a digitally controlled 40 Meter HF SSB (Single SideBand) transceiver designed mostly by Ashar Farhan. He’s a really smart man who lives in India.
The BITX40v3 being discussed here is a “short kit” which includes almost everything needed to complete a radio and get on the air. Soldering some connectors and wires is required. The kit is made to be hacked:changed, modified, customized, deconstructed, rebuilt, broken and repaired. It’s like buying a box of legos already made into the final shape. You can just leave it that way, or you can tear it apart and change it as you see fit.
Is this the only BITX radio being sold? I see other BITX kits online too.
The BITX40v3 circuit board and associated pieces commonly being referred to are among many versions of the BITX being sold. There are also BITX20 kits made by other companies. The BITX design is not copyrighted, and schematics can be found for free if you wish to build your own version. The BITX40v3 PCB layout is copyrighted.
Where do I order a BITX40?
You can purchase a BITX40 at http://hfsigs.com. It costs $59 shipped worldwide from India.
How long will it take to get it?
It’s variable, but figure 2-3 weeks for most destinations. Don’t trust the tracking number. It often gets no updates for weeks and suddenly, there’s a BITX40 kit at your door. Just be patient, it’ll get there eventually. This isn’t Amazon Prime.
What if I need to contact Customer Service?
You can email them directly at email@example.com. Don’t expect an immediate response. This isn’t Amazon. This is some nice folks in India selling an inexpensive kit, providing jobs for locals and doing their best.
What supplies/parts do I need to finish it?
The BITX40 kit comes with a completed circuit board for the radio and the digital tuner, the Raduino. You’ll need some soldering equipment and an enclosure for the BITX40. If you want a speaker, you’ll need to supply one, as the BITX40 comes with a headphone jack only. A simple 8ohm 3w speaker will provide plenty of volume. Others have used computer speakers plugged into the headphone jack. It’s completely up to you.
I don’t know how to solder. Is it hard?
Most worthwhile things have a learning curve, and soldering is no different. It’s not difficult or expensive. If you’ve never soldered in your life, then this would be a simple project to start with. Search Youtube for “how to solder electronics” and “How to care for a soldering iron” before you start. A 25W soldering iron, some thin rosin core solder (not lead free!) and some patience is all that is needed. See our recommendations here.
What is the Raduino?
First, a bit of history. Before late December 2016, the BITXv3 was sold with an analog VFO. The VFO (Variable Frequency Oscillator) is the part that both provides the frequency to the radio and varies it for tuning. When the tuning knob was turned, the VFO would change frequencies. Simple stuff, but not very reliable. The frequency drifted, sometimes significantly, making it difficult to stay on frequency. It also had no frequency indicator to show you what frequency you were tuned to. But the kit was only $45 and for $45 one need not expect perfection.
In late December 2016, hfsigs.com announced that the BITX40v3 now came with the Raduino, which is a digitally synthesized VFO. It produces the correct frequency and displays it on an LCD screen. It uses the Si5351A signal generator chip to create a stable signal, and an Arduino controls the synthesizer and the LCD. You get a digital readout and and control, just like the big expensive radios get. The price was raised to a modest $59.
I have an earlier version of the BITX40v3. Can I get the Raduino separately?
Yes. You can email firstname.lastname@example.org and for $25 you can get one shipped to you. You can also get the QRP Labs VFO kit which is $33 + Shipping, and works well with the BITX40v3.
Can I buy a BITX40 pre-made?
Not commercially, no. The point is to build one. It’s part of the process. And, it’s fun!
Do I need a Ham Radio License?
Yes. You need a General Amateur Radio License (in the US) to transmit. To listen, you do not. But who wants to just listen? Get the General license. It’s Not That Hard.
Where do I go if I need help with my BITX40?
The official support for the BITX40v3 is at https://groups.io/g/BITX20. It is an email based group, but you can turn off email and just use the web interface if you prefer. And don’t let the name BITX20 fool you. It’s the right place. You’ll see people discussing other versions of the BITX there too.
Can the BITX40 be modified for 20/80/10/17/12/60 Meters? CW? AGC?
Yes! That’s the whole idea. Check out the official support group, plus excellent sites such as
And from our own archives:
Why does Voltage Regulator on the Raduino get so hot?
Voltage regulators work by dumping excess voltage as heat. As a result they can get very, very hot. Don’t be alarmed by it. The data sheet shows that they can handle 125c (257F!) before shutting themselves down for safety. If it gets too hot for your comfort, a small heat sink can be added, but it is not necessary.
Yes, that’s it for now. If you have a question you’d like answered, please feel free to leave a comment below. Thanks!
PS- Yes, the Q looks weird in this font, and for the moment, I’m not going to change it because everyone still knows it’s a Q.