These power pentodes has been used as a transceiver final (one or pair of ones in parallel), in a modulator for the more powerful tube in AM transmitters, in a driver stages and (when SSB times comes) in the most common general class amplifier - three (or four) GU50 in parallel with all grids connected to the ground.
GU-50 is russian version of WWII Luftwaffe LS 50 general purpose HF power pentode by Telefunken, also known as RL 12 P 50 tube in Wermacht's transmitters. Main difference between russian and german versions - socket construction and dimentions, so I'm not quite sure that it is possible to use russian GU-50 as a spare part for a vintage german transmitter.
There are several other members in this family, such as DDR SRS 552 M tube, SL 152 (~12.6V filament) and EL 152 (~6.3V), but I don't know any more about these tubes, only that these tubes exists.
|GU-50||Filament Voltage||12.6 volts||LS 50|
|Filament Current||0.77 amps.|
|Input Capacity||14 mmfd.|
|Output Capacity||9.2 mmfd.|
|Grid to Plate Capacity||0.1 mmfd.|
|Maximum Plate Dissipation||40 watts|
|Maximum 1-st Grid Dissipation||1 watt|
|Maximum Screen Dissipation||5 watts|
|Frequency Range||120 mc|
|GU-50 Height||93.5 mm.|
|GU-50 Diameter||45.3 mm.|
German LS 50 pentode
APPLIED CW CHARACTERISTICS (Grounded Catode)
APPLIED SSB CHARACTERISTICS (Grounded Catode)
APPLIED SSB CHARACTERISTICS (Grounded Grids)
Soviet GU-50 (ГУ-50) Pentode