Valve Linear Amplifiers WILL KILL!!! If you make a mistake there is no SECOND CHANCE, so you have to be VERY VERY careful before you start working inside them.
I am writing this because of some stories I have heard that frighten me, as we are talking about HIGH VOLTAGE in excess of 2.5 THOUSAND VOLTS with high current which is a lethal combination. and I hope that I have managed to scare you into taking notice of the safety measures which should be adhered to. I have worked with mains voltages and above since the age of 16 and have a healthy regard of electricity and know that it can bite so always take precautions when working with it. With the high voltages found in linear amplifiers you have to be extra careful as it does not bite it KILLS.
Before working on a linear amp, if the high voltage circuit has been activated then you have to leave it for at least half an hour for the power supply to discharge before touching anything. I built a 2.5KV high voltage meter into the linear amplifier that I am building so that I would know when it was safe to put my fingers inside it. DO NOT short out the EHT as you can damage the linear doing this. You LIVE LONGER with a little bit of patience.
Recently I heard a story of someone who wore Marigold Gloves as a safety measure when working on a live linear amp, I personally think it safer to work with bare hands with the power supply fully discharged. This same person upgraded his power supply from 800 volts to 3 thousand volts to get more power, his valves actually exploded. If something goes wrong in a linear amp, because of the power there is usually a BIG BANG.
The motto of this story is to Listen to people who know what they are talking about, research your amp so you know more about it and don’t work on a live linear, stay safe to be able to use the linear and make sure it is not sold in a Silent Key sale. (I asked Jonathon G6JUT if he would like to place an advert for his business on this post but he declined as he thought it would be in poor taste.)