Smitty Working on SOMETHING: BitX-40 QRP Home Brew Radio

The BitX-40 is a QRP (low power) 40m (7MHz) SSB (voice, not morse code) transceiver designed and sold by Ashhar Farhan, VU2ESE. It is a very simple-to-understand radio that you can make yourself and hack on. It's a very good platform to learn how radios work, and to get comfortable assembling and tweaking things.

In this video, I'll explain how the radio works (and indeed how many radios work!) at the block-diagram level, assuming no prior knowledge of how RF circuits work. The only math we'll be doing is addition and subtraction, the only electronics we'll be doing is opening and closing switches. All other details will be hand-waved in a desire to explain the BitX 40 at a high level, allowing you to dive into more details as you desire.

[CarolinaCoxes]

Thanks for the insightful video Smitty. I heard you on the 360Workbench podcast and decided to check out the video you mentioned. I built (well, actually wired up) my BitX40 around Christmas and then bought another one that I want to attempt some modifications on. Your video helps a lot. 73, N4MN

[jmcexx]

thank you. perfect level of detail and well organized.

[nimroddiaries_]

Wow. I almost understand the basics now. Lol. great video. thank you

[karlschwab]

With each video I can find and see on the BITX40, I am able to understand a little bit more on the fabulous 40m SSB transceiver kit!  I put mine together, it worked and I made several QSO's; amazing!  Now I need to add some hardware improvements, like a hand/desk mic w/switch to start.  Maybe even an LED when the transmitter is keyed would be fun to watch, but again, how would I do that?  I put mine in a clear acrylic case so all of my handy work can be viewed and appreciated; don't know if this is an RF concern, but I'll see in time.  I do not know anything about the software (sketches) or how to get them to this radio, but perhaps a Group Build here would include that.  Thanks again for your excitement with this radio; I'll be looking for more!  73, Karl, KO8S

[jeromegrzelak]

I love mine finally it got placed in the box the fine screws drove me nuts kg6mn

[californiakayaker]

I think you need to look at some radio theory, as you have some things confused. This is a double conversion radio. How would you know that ? Two mixers is a dead giveaway. Another dead giveaway is Ashar Farhans explanation at HFSIGS.com where he says 45mhz roofing filter if and 12 MHz crystal filtered IF. Takes a conversion for each IF. So, study, then do videos. Your confusing these poor people ! And, yes, looking at Wikipedia for instance, you see super heterodyne explained, two versions and pages, original 6 tube am receiver with a 455 kHz IF called single conversion super heterodyne, and a page for the dual conversion super heterodyne.

[paula]

Great explanation! Really helped me understand how a transceiver works!

[pacorumblefish]

"...all kinds of fun wackiness..."