In the years 1951–1954, Czechoslovak Army was gradually refitted and thus, it became fully combat capable, contemporaneous, conventional armed force. In the course of the fiftieth, modern radio stations of domestic design school were coming to the units and replacing the stations of the trophy origin. Beside the RM-31 station, it was namely the portable short-wave RI-21”LIBEŇ” radio station which was introduced in 1955. Development of R-3 “MARATON” receivers, made in Military Technical Institute and R-4 station, made in TESLA Pardubice factory, fall into the first half of the fiftieth as well. In the sphere of line equipment, they developed TP-25 field telephone apparatus produced by TESLA Valašské Meziřičí.