testing cathode current

[jpdylon]

I install chassis mount fuses where convenient and connect the fuse holder in series with the cathode circuit. Not only will the fuse blow if there is a failure, likely saving the flyback, but i can remove the fuse the connect an ammeter across the empty fuse holder to adjust the cathode current.

I advise buying an autoformer or variac and run your set at 110v like it was designed to. 120v is a little too high for these sets and will decrease their service life. You may also not be able to bring down the cathode current to or below the recommended value without doing this in some sets.