USSR VHF RF amplifier UM

USSR VHF RF amplifier UM complete with HT inverter R-104M (left). The original supplied dummy load (made up from four 200 Ohm resistors in parallel) is in position on the aerial base on top of the RF amplifier.

USSR type UM is a VHF RF amplifier used to amplify the RF output of the R-105D/R-114D family of manpack VHF FM sets, thus increasing its operational range. Its principal use was in a R-125 vehicle installation along with HF radio R-104M. The UM was first issued in the early 1960s and used a valved RF amplifier (type GU50) and transistor HT inverter unit.

• Frequency coverage 20-46MHz in three pre-set ranges.
• RF output more than 40 Watts
• Suitable for FM R/T only.
• Amplifier is mounted on top of R-105D/108D/109D/114D.
• Powered by 12 V. HT is obtained from transistorised inverter, identical as used with R-104M.