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Originally Posted by leadlike
Would you mind explaining how to hook all of this up to monitor cathode current?
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Sure, but let me explain my way of doing it as well.
Sams has you use different moving needle meters to make the measurements: a 0-1ma meter for the 6BK4 cathode, and a 0-500ma one for the 6DQ5. Normally you would either unsolder a ground connection (in the case of the 6DQ5), or clip a little wire jumper (on the 6BK4) and place the meter inline to take current readings. Instead, I chose to permanently install 1-ohm 5-watt resistors from the cathodes to ground. This allows me to set the DMM to read voltage instead, so I can move 1 meter around vice watching 2. It gives the same exact readout as it would if you were reading current, I just think it's easier to move leads around to different resistors.
Plus it's somewhat less dangerous-not so many wires to run into while making adjustments. And even if I did bump a lead loose, there's little risk of hurting anything since the circuit would still be complete. If you measure current with an inline meter on the 6BK4, I shudder to think what would happen since the high voltage would be instantly unregulated if a current meter lead came loose.
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The Sams says to remove a jumper, but I have yet to see where this jumper is at that I can hook my ammeter to...
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For the 6DQ5, you have to remove the ground wire on pin 3/6 for a current reading/install resistor for voltage reading. On the 6BK4, you have to follow a wire from pin 1 back to a terminal strip. On the strip, you'll find a little loop of wire. Clip that loop, and insert the current meter or install the resistor.
