TI-426 SATURN is a member of the first line of Czech radiotelephones, developed exclusively for the ordinary and secret police. It is a single channel, crystal-controlled transceiver, produced in variations for both battery and mains powering. The whole line of those radios had a couple of members, named by space-realted names. There was, together with Saturn, the three channel radio TI-423 VENUŠE (Venus), TI-460 JUPITER and a base station, named VESMÍR (The Space). All these radios used FM.
The schematic diagram is available at very interesting Miro, OM3CU's pages - worth to see them! Anyway - thanks to Miro for identifying this radio!