Historic 150W Tube Amplifier Telefunken Ela V407 from 1937

Pictures here: F/ Tubeamplifier - operates two triodes RV278 (thoriumoxide-cathode), each 50W plate dissipation, 1100Volts. RE604-driver and parafeed circuit. Towards the end you heare the input-choke of the power supply reacting with the variing load, meanwhile the amplifier is connected to a dummy.