The most popular ARDF receiver in Czech ever. Made by URD (Central Radioclub Manufactories) since the begin of 70ies as at a successor of JUNIOR receiver, there are some improvements made, but the basic concept remains the same - single direct conversion receiver, balanced mixer, simple two-transistor AF amplifier. The main improvement are the plastic ferrite antenna protectors - very useful! At the other hand, the rod antenna, made from bicycle wire and mounted by only an M3 screw apperaed very fragile and frequently broken.
Not lookin to that, there were plenty of those receivers made an they proved their very simple, easy-to-repair and very long lasting design. Running from one 4,5V flat battery, the operational time was pretty sufficient for many contests.