Linear PA without HV trafo with 3 – gu50

This is very small and light PA, but with power more of 300W output in CW mode and 500W pep in SSB mode. In the PA there is not trafo for HV. The plate voltage is the quadrupled electrical mains AC voltage. Special relays circuit look for correct connection the phase and ground wire to the PA and automatically switch in right position. Nevertheless there is no danger from electrical stroke, because the AC ground wire is ALWAYS on the chassis and there is not contact between the dc supply wires and chassis.
In the PA is used very popular and chip Russian tubes GU50. The maximum plate voltage of this tube is up to 1200V, that is suitable to use multiplied mans voltage (3-4 times) with 1N5408 diode and small electrolytic capacitors from computer PS.

Shematic diagram in pdf file !

Power supply view Here !

Coils is Here !

Full info is in Bulgarian language !

Original from page of LZ2ZK (sk)