No, I got one that reads mA. Not, to confuse thing but I have the same issue with a jcm 900 4500 where I couldn’t get to the targeted adjustment on the bias pot. (No voltage drop or blown fuse with this amp)
So, I got a new fuse in and I’m back to the 440v plate voltage, I biased it a little cold 36ma vs 39ma, but the amp still sounds crappy, as if the guitar is out of tune, especially the higher strings (line there’s phase cancellation). I’ve tried other guitars, cables, speakers. Any thoughts?