There are dozens of QRP rig designs and new kits that pop up each year, the majority of which are reiterations of previous designs. For the past ten years it seems we’ve been in a bit of a rut building NE602 based direct conversion and superhet rigs. But once in awhile a groundbreaking design is released, and everyone follows. Rigs like this are truly memorable, like the W7ZOI Ugly Weekender, the NEophyte, the Norcal 40, the 2N2/40, and the K2. I think the Minima, a new transceiver designed by Ashhar Farhan is one such design. The design has really impressive and innovative features:
- 1 to 30 Mhz coverage
- CW and SSB operation
- Si570 DDS local oscillator
- 20 Mhz IF
- KISS Mixer
- Arduino controlled, with open source software
- Other than a few ICs, most of the active components are general purpose NPN and PNP transistors
- A relatively simple and reproducible design
Looking at the schematic, you can see immediately how unique it is starting at the front end. From the antenna jack, you go into a high pass or low pass filter and then hit a mixer with two FETs. After that is an IF amplifier constructed from bipolar transistors, a BFO mixer and then the audio chain, again built from bipolar transistors. The transmitter chain works essentially the same, in reverse, with the mixer as the final active stage and providing a one watt output.
I’ve been eager to build something ugly style on a sheet of copper clad PC board, and this is just the ticket. And it’s Arduino controlled which is icing on the cake!