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Guest
Guest
Mr. Oliver Archut explain how to measure steel tubes. Could somebody draw
test circuits from the explanation below:
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In any case, before installing a tube you should measure it and you dont need a tube tester to measure the static data. Plate 250V 2nd grid 200V (over 25k buffer resistor) with a 2nd grid current of 1.9mA and a cathode resistor of 350 Ohm you should get 12mA cathode current with a good working EF/VF14. The grid leak resistor should be 3M ohm and the reverse grid current less than 1uA. If you attach a plate resistor of 50K you can test the dynamic values with a sine wave generator. An E/VF14 should be able to reproduce 10 to 10K with open load (+/-0.5dB) with a plate inductor of 100H (the tube was mainly designed for LC and not RC coupling) the tube should be able to reproduce 10 to 100k with open load (+1/-0dB).
test circuits from the explanation below:
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In any case, before installing a tube you should measure it and you dont need a tube tester to measure the static data. Plate 250V 2nd grid 200V (over 25k buffer resistor) with a 2nd grid current of 1.9mA and a cathode resistor of 350 Ohm you should get 12mA cathode current with a good working EF/VF14. The grid leak resistor should be 3M ohm and the reverse grid current less than 1uA. If you attach a plate resistor of 50K you can test the dynamic values with a sine wave generator. An E/VF14 should be able to reproduce 10 to 10K with open load (+/-0.5dB) with a plate inductor of 100H (the tube was mainly designed for LC and not RC coupling) the tube should be able to reproduce 10 to 100k with open load (+1/-0dB).
