Re: DC heater supply valve tester.
Putting a diode in the feedback loop of the linear regulator starts to defeat the purpose of this experiment (High efficiency)
If two parallel , relatively fast diodes are used to protect both the switcher and linear regulator from reverse polarity.
The Sussex tester uses current limiting, as do all my homebrew testers, i wouldn't design without it to be honest. if heaters are lit up, the heaters will eat up the extra current.
Internal shorting is rare in my experience, a tube should be rejected for shorts before HT is applied.
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