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RE: Installing a current meter..

Posted by Johno on June 18, 2017 at 17:55:20:
As already mentioned a good ole fashioned Simpson ie not china made meter should be fine. I still reckon any form of fusing is ideally suited in the HT side.

The alternative which is more expensive but bullet proof is to use a Volt meter across the kathode resistor. Jacmusic has some good info at there website under panel meters ie Yamamoto Panel meters

Verbatim below from above website
Yamamoto Shunt designed current meter, for tube autobias only
Please take a moment time, to understand those intelligent meters, because these are not like any other. When measuring the plate current of a tube, it is generally not desired that the signal path will go through the ampere meter. Reason is, that Ampere meter has a coil inside, and any Audio signals would be disturbed by this coil. The intention of these meters is to prevent frequency dependent effects, and other kind of interference. Besides not all low cost meters will indicate precise.
Yamamoto has found a nice solution for this. The meter is connected in parallel to the cathode resistor, and the meter is high impedance. This method is really genius. The meters gets a series resistor, which you can conveniently calculate.
What is also good to know, is by this method the meter has excellent short circuit protection. If by any mistake you make a short circuit, the cathode resistor will absorb the short circuit energy, not the meter"

Johno