G4DCV GS31b 144MHz Amplifier/gs31-12.jpg
If you do not understand high-voltage safety procedures do not attempt to build a tube amplifier.
The HT voltage will kill
I use a clear plastic internal cover fixed over the power supply compartment of the amplifier and since this picture was taken I have added an internal warning sign. It allows me to have a look inside the PSU and prevents accidental contact with the amplifier running although if everything is normal there is nothing dramatic to see. The internal cover is also intended to make anyone who unscrews the top cover stop and think before proceeding further.