A matchbox transceiver, the ultimate minimalist radio setup. Ever wonder if you could transmit Morse code using something the size of a matchbox ? Today we’re designing a minimalist transceiver with only three transistors. A combination between the Pititico designed by Miguel – PY2OHH and the uu80b designed by Roger – G3XBM. The idea of placing it in a matchbox just like a secret spy CW transceiver comes from Helge – LA6NCA. In the video above I started from an improved version of the uu80b transceiver, converted for the 40m band. The matchbox transceiver it’s one of the smallest and simplest transceivers designed around three 2N2222 transistors. With only a handful of components and a power output of 550mW @ 12V or 350mW @ 9V. A great project for beginners in building amateur radio transceivers. Since it’s so small it will require some patience and a lot of attention. The circuit works as a low-power oscillator ( Q3 ), capable of reaching 1W and currents of 100mA ( remember that the 2N2222 is for 80mA ). The transistor handles this current well in CW, but don’t keep the key activated for too long as the transistor will burn out. Another problem is operating without an antenna or a dummy load, the transistor will burn out. I would recommend to power it at 9V with 350mW output power as the transistor doesn’t heat up so much. C7 allows you to tune the TX frequency. I added this one so I can tune it exactly on 7.023MHz. Depending on the crystal used, you may have to change the value of C7. For the 7.023MHz crystal 47pF was optimal and we have both the TX frequency exactly on 7.023MHz and also the 800Hz offset frequency on receive. More details in the Blog Article.

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