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Old 30th Jun 2020, 8:09 pm   #43
AdrianH
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Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 892
Default Re: Yes, yet another home made valve tester.

Today I managed to get a switch that had three positions so I could do 4, 40 and 80 mA ranges.

So I used David's standard valve again and started to plot going up to 80 mA range, but after 45mA of anode current the valve would break into oscillation again, so a few hours have been spent trying to figure out why.

Then on a whim I removed the 0.047uF caps I had on the Octal pins, so now only the 1nF caps on the Banana sockets and the ferrites on the leads of course. Instant karma, no signs of instability over the full current meter range.

So for reference I did a full run entered the figures in the spreadsheet and provided plots, the valve has been getting a few hours work today, can emissions improve slightly with use?

Now to test some of my valves!

Adrian
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