[Ashhar Farhan]’s done it again!

If you are a regular follower of these pages as well as a radio amateur, you may well have heard of [Ashhar Farhan, VU2ESE]. He is the designer of the BitX, a simple single-sideband transceiver that could be built for a very small outlay taking many of its components from a well-stocked junk box.

In the years since the BitX’s debut there have been many enhancements and refinements to the original, and it has become something of a standard. But it’s always been a single-band rig, never competing with expensive commercial boxes that cover the whole of the available allocations.

With his latest design, he’s changed all that. The uBITX (Micro-BITX¬†when spoken aloud), is an SSB and CW transceiver that covers all of the HF amateur bands, and like the original is designed for the home constructor on a budget. It shows its heritage in the use of bi-directional amplifiers, but diverges from the original with a 45 MHz first IF and an Arduino/SI5351 clock generator in the place of a VFO. It looks to be an excellent design in the spirit of the original, and we can’t wait to see them in the wild.

He’s put up a YouTube video which we’ve placed below the break. His write-up is extensive and fascinating, but it is his closing remarks which sum up the project and the reason why you should build one. We don’t often reproduce entire blocks of text, but this one says it so well:

As a fresh radio amateur in the 80s, one looked at the complex multiband radios of the day with awe. I remember seeing the Atlas 210x, the Icom 720 and Signal One radios in various friends’ shacks. It was entirely out of one’s realm to imagine building such a general coverage transceiver in the home lab.

Devices are now available readily across the globe through online stores, manufacturers are more forthcoming with their data. Most importantly, online communities like the EMRFD’s Yahoo group, the BITX20’s groups.io community etc have placed the tribal knowledge within the grasp of far flung builders like I am.

One knows that it was just a matter of breaking down everything into amplifiers, filters, mixers and oscillators, but that is just theory. The practice of bringing a radio to life is a perpetual ambition. The first signal that the sputters through ether, past your mess of wires into your ears and the first signal that leaps out into the space from your hand is stuff of subliminal beauty that is the rare preserve of the homebrewer alone.

At a recent eyeball meet, our friend [Dev(VU2DEV)] the famous homebrewer said “Now is the best time to be a homebrewer”. I couldn’t disagree.

If you build a uBITX, please share it with us!

We brought you news last year of an earlier iteration of this design, and in the past we’ve shown you the original. What more impetus do you need to get yourself an amateur radio licence?

Thanks [Pete WB9FLW].

13 thoughts on “[Ashhar Farhan]’s done it again!

  1. Indeed, the ecosystem that’s grown up around his BITX40v3 is pretty amazing, and it has been my re-introduction into ham radio after many years, and an introduction into all sorts of learning for me. I’ve written about ham radio and the BITX40 on my blog http://miscdotgeek.com/category/bitx40/ and am looking forward to seeing what happens with the uBITX. I don’t have the chops to scratch build one just yet, but I’m getting there :)

  2. VU2ESE explained the simplicity of the uBITX at Eye-ball meet of LARC (Lamakaan Amateur Radio Club, Hyderabad) earlier this year. The thought process behind designing the circuit and the simplicity of his design was amazing. The coarse and fine frequency tuning functionality that he has implemented with a single knob is very elegant.

  3. The uBITX is a welcome evolution. The BIG question is, will it move to “production” like the recently released BITX40 “Fully-Assembled” $59 single-band HF transceiver? (Actually “Fully-Assembled” is arguable because while you get fully-assembled boards, you must add your own enclosure and other bits-and-pieces to make the thing a stand-alone radio.) See here for more on the BITX40 “semi-kits” as I call them:

    http://www.hfsigs.com/

    For the BITX40 “semi-kits”, Farhan is leveraging the economies of scale for parts (e.g. crystals in bulk via the likes of ebay) and labor. These analog radio boards require crystal filters which use crystals that must be matched for motional-parameters – by humans. Farhan (IMO) is thinning this bottle-neck by sourcing large numbers of crystals and using relatively low-cost human labor in India to match them. This is a practice I support, provided the labor is compensated at good local rates and the workers are treated fairly.

    Note, it remains to be seen how a design like the uBITX will perform in terms of unwanted spurious and image products. (Let’s not forget Farhan’s belated (IMO) “Minima” design). The uBITX is a very different design compared with the Minima, in a good way – but I will wait to see how it performs at a production level in terms of important specifications.

    Moving on…

    While I applaud Farhan’s work in this area, it’s still mired in the analog world. IMO what we need is something completely different.

    What we need is a “Building Block” base for a STAND-ALONE (no PC, no sound-card) HF Software-Defined-Radio. This would be an easily purchased pre-built main board with a microcontroller capable of acting as the SDR modulator/demodulator block. RF in/out filtering would be external. A stand-alone direct-conversion quadrature SDR is a good candidate provided there is a “front-end” that minimizes the antenna input impedance effect on overall SDR performance, and rejection of the L.O. signal leakage through the antenna port.

    There has been some work done in this area with the likes of the Teensy microcontroller boards. But IMO it’s not there yet.

    What we need is an Arduino-like design for HF SDR’s that’s easy to deal with in terms of the development tool-chain. (Yeah, like NOT having to fight with the likes of a nightmare GNU-Radio install attempt plus the need to have an an EE Degree to do simple things).

    I believe the day for this “easy” homebrew SDR building block coming soon. The higher-end STM32F series of ARM-based microcontrollers are close to what’s needed. But we need (1) simplified IDE/tool-chains/libs, (2) an open-source and readily available for purchase basis module/break-out-board, reasonable documentation (a Wiki helps), and MOST IMPORTANT – a “Community” to support the thing! Think the “Arduino Community” model, but for simple SDR’s.

    1. That sounds great. When are you going to get started developing this HF SDR? Meanwhile, I already have a bunch of digital communication stuff, and want to stay in the analog world. I have big radios, but want the smaller size, hackable, portable designs like Farhan is creating.

    2. There are some boards along the lines of what you mentioned: the stm32-sdr ( http://www.stm32-sdr.com/ ) is all the digital stuff, where you bring your own front-end. Or, you know, my own PortableSDR (most up to date info at portablesdr.com in the updates section) or portablesdr.net (just a link to my hackaday.io page) which is the digital/interface stuff and includes the RF front end (but needs improvement)

  4. This is what ham Home brewing needs: bringing building your own radio to the 21st century.
    I looked at a lot of projects hopeless stuck in the past the information has not changed since the 1990’s. I tired of fellow old has think we should build and work like it still 1970.

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