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Old 5th Sep 2019, 9:31 am   #125
GMB
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Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,092
Default Re: Mullard Valve Tester Card Project

There are interactions between the features so it isn't trivially simple.

By way of example, you might have expected various holes to select the heater voltage, but actually you find cards with different hole combinations in the heater area for valves with the same heater voltage rating. The reason is that they actually allow for the effect of the current drawn loading the transformer.
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