Problem with AVO Mk2 tube tester

Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

Hello,
I have three AVO Mk2 Tube Testers, and they all show the same problem. Who has experience with the Mk2?
The problem is, when I calibrate it by the book, it indicates 40% too much plate current for small tubes like ECC81 , and 40% below for the big tubes like 2A3.
So a known to be good 10.5mA ECC81 tests at 14mA, and a new 2A3 that I know has 60mA tests at only 33mA.
All three of them show exactly the same behaviour. Since those testers work by a very strange principle, it is hard to say what I measure inside the tester is right or wrong.
What makes me crazy, I have three of those that I purchased from three sources and they all show this behaviour.
Who has experienced the same problem?

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Topic - Problem with AVO Mk2 tube tester - EML 08:14:43 09/20/06 (6)

check the grid pot - lovetube 01:02:32 09/21/06 (0)

Re: Problem with AVO Mk2 tube tester - fatbottle 09:29:03 09/20/06 (0)

My AVO Mk 3 is the same... - jub_jugs 09:24:21 09/20/06 (1)

BTW - jub_jugs 09:25:03 09/20/06 (0)

Re: Problem with AVO Mk2 tube tester - Chris O 08:51:23 09/20/06 (1)

Re: Problem with AVO Mk2 tube tester - andy evans 08:56:57 09/20/06 (0)

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