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Old 10th Jan 2010, 1:03 am   #41
retailer
Heptode
 
Join Date: May 2005
Location: Adelaide, South Australia
Posts: 541
Default Re: Homebrew Valve Tester

Well done swordholder you stand tall amongst us, anyone that has scratch built something before will know the amount of effort that you have put into your project.
I built a valve tester from a circuit designed by Steve Bench about 6 yrs ago, some readers will know it as the RAT valve tester. I'm a hobbyist not a design engineer so it wasn't a hard decision to use someone else's idea. The RAT tester uses a variable constant current source at the cathode to control the anode current and the valve then sets it's own bias, it does work well. I think that the AVO 163 is able to use either variable constant current source or variable grid bias to test valves.
I had planned to wire the valve base setting switches so that the AVO data manual could be used, but decided that it wasn't entirely a good idea. I can't recall exactly what the problem was but it may have been peculiar to the RAT tester circuit only.
The 200mV AC panel meter that you've used looks very good, I didn't know of their existence 6 yrs ago and had to make my own. I'll look forward to reading the full HOW TO article when you get it done.
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