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Practical High Voltage Power Supplies Click to step through the presentation Ian White, GM3SEK Practical High Voltage PSUs • Safety + Reliability • Practical circuits and components Safety + Reliability Thousands of amateurs use HV safely, every day. So can you! But your first big mistake will be your last, so… DON’T MAKE MISTAKES! Always think about what you’re doing and you’ll be fine. Safety + Reliability Good safety habits: 1. Defence in Depth. • Multiple barriers against failures and accidents. • NEVER be only one fault away from danger. • ALWAYS unplug from the mains. • ALWAYS discharge HV circuits before touching. • Multiple earth bonding – very important. • ALWAYS be thinking what could possibly go wrong… and then prevent it! Safety + Reliability Good safety habits: 1. Defence in Depth. 2. Build safety into hardware. • Don’t rely on ‘being careful’… because one day you will drop your guard. • Use good quality components and construction. • Greatest risk when testing and repairing. Use safety covers inside (clear acrylic sheet). Safety + Reliability Make these into your way of life: 1. Defence in Depth. 2. Build safety into the hardware. 3. Don’t ever stop thinking! Safety + Reliability Reliability – for DX and contesting Building reliability into the hardware: • Good quality components and construction. • Under-run all components. • Check all component ratings. • Use cooling fans. Practical High Voltage PSUs Safety + Reliability • Practical circuits and components Circuits and Components Circuits and Components Mains Circuits and Components Transformer Circuits and Components Rectifiers + capacitors Circuits and Components HV+ output Circuits and Components HV-minus return Circuits and Components Circuits and Components Mains Circuits and Components Transformer Circuits and Components Transformer Circuits and Components Transformer Circuits and Components Transformer Circuits and Components Circuits and Components Circuits and Components Circuits and Components Rectifiers + capacitors About 30uF Bridge rectifier is best! Circuits and Components HV+ output Surge limiting HV socket resistor • Coaxial (“Glitch resistor”) • SAFE connector! • Earth bonding Circuits and Components HV-minus return Why a separate HV-minus return? Chassis earth Circuits and Components Anode current HV-minus return Grid current Anode current Circuits and Components HV-minus return 5-pin XLR socket: Chassis earth Important safety precautions. •HV HV-minus (duplicated) won’t turn on unless this is • Earth (duplicated) plugged in. • HV control input • Connector shell also earthed. Circuits and Components Practical High Voltage PSUs Safety + Reliability Practical circuits and components For more details… • Radcom January-February-March 2009 • The ‘In Practice’ website: http://tinyurl.com/inpractice © 2009, IFWtech Limited. All rights reserved.