SM6GFR/Staffan






                                                                 PA under construction



Presently I am rebuilding a HF power amplifier which has 2  QBL3.5-5000 in parallel. Grid-driven construction.
At the bottom the 3x220 V, (1100 V secondary) transformers will be. 3-phase-rectifiying and voltage doubling, delivering abt 3 kv , 1,5 A at full drive(20-40W input). Screen voltage 800 V. Bias -70 V in transmitt mode. Filament current 70 A.

 

 



Below is the tank circuit. One of the QBL 3.5/5000 can be seen and behind a vacuum capacitor (C1), C2 below.
To the left the band-switch, and 80/40 meter coils to the right, 10/15/20 coils behind.