Low frequency amplifier `` UM-3 ''.
Amplifying and broadcasting equipmentThe low-frequency amplifier "UM-3" was planned for release in 1932 by the Kazitsky hardware plant. LF amplifier "UM-3" is designed for small radio broadcasting nodes as the main or terminal. The amplifier is fully powered from the AC mains. The maximum output power of the amplifier is 3 W. The amplifier works both from the low-frequency output of any radio receiver and from a microphone.