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PLate Voltage Measurements

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11/28/2005 8:47 PM

PLate Voltage Measurements

I have seen many bias tool sockets out there that allow measurement of the plate current. I want to use a similar adapter to measure the plate voltage too. Here is the trick, can I get a ground connection from the heater supply? Is it standardized that the 6.3VAC heater supply will be grounded? It seems that either the center tap will be grounded or one side. Worse case there will be two 100 ohm resistors providing a virtual ground. Any thoughts ?

Keith

11/28/2005 10:52 PM
Don Symes	If the amp isn't cathode biased, just use the cathode pin (even if the 1-ohm bias-check resistors are installed).

11/29/2005 5:50 PM
Enzo	Even if it is cathode biased, all the tube cares about is the voltage between cathode and plate. Chances are that he isn't adjusting bias on a cathode biased amp anyway. So in that case the cathodes are esentially ground.

11/29/2005 8:19 PM

Hi Enzo -
I was originally talking about a 5E3 which is cathode biased. I want to build a nice meter/tool that can measure the plate voltage, screen voltage and plate current.
I did some simulations that show as long as the 6.3V heaters have a path to groung this should work. Obviously if the amp is fixed bias the cathodes are grounded so that is not a concern.
I will try some measurements on my amp and put something together, no better way to find out than to try it.

Keith

11/29/2005 8:39 PM

quote:
"Chances are that he isn't adjusting bias on a cathode biased amp anyway."

Oh. Duh.

/ "It's pronounced doo-mah."

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