The PIONÝR receiver was designed as a simple, cost acceptable receiver for young SWLs and beginner operators. The concept is very simple and straightforward, radio is designed as direct mixing receiver with half-balanced active mixer and varactor tuned VFO. The frequency stability is, thus, very poor and the tuning is very coarse (one 3/4-turn potentiometer over the whole band). In a fact, there is an "fine tuning" pot too, but the comfort of the tuning is very low. As any other direct mixer, the radio suffers from strong, out-of-band local transmitters.
At the other hand, the design is very cheap and for such a simplicty, the radio sometimes surprises by sensitivity and quality of reception. The power is either 3x "flat" 3F12 battery, or external 12V. The power drain is very low, thus, one battery set lasts for months of daily listening.
This receiver was produced in per-band modifications, so far I know about versions for 160, 80, 40 and 20 meters band. In my collection, there are models for 20m and for 80m, versions with a loudspeaker or headphone output. They are all in a good shape, fully working, no mechanical nor electrical damages. The schematics is available, thanks to Petr, OK1RP. Have a look also at the full article scan on this receiver, including PCB layout, component placement and building guide. Enjoy!