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Old 22nd Nov 2017, 8:47 am   #21
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Join Date: Aug 2007
Location: South Bradford, West Yorkshire, UK.
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Default Re: What is meant by "kinkless"?

Here are a couple of plots taken from my 2016 talk at Golborne on Valves. They show the anode current vs anode voltage with the G1 and G2 voltages set to a fixed value.

Both are taken using an EF91, one configured as a tetrode with G3 connected to the anode and the second configured as a pentode with G3 connected to the cathode.

The full text of the talk is in this thread

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Old 22nd Nov 2017, 10:37 am   #22
Join Date: Feb 2007
Location: Lynton, N. Devon, UK.
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Default Re: What is meant by "kinkless"?

Well, that's definitely a kink! Although it is not a massive fall in anode current in the 'awkward' region, the effect is definitely there!

Different samples of the same valve may give widely different results. Secondary emission is dependent on the (inside) surface of the anode, so slight variations in alloy composition or surface finish could alter things a lot. For normal, intended, pentode operation, of course this would not matter, so manufacturers did not have to control it.
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