Robert Baer wrote:
Some 12Au7 tubes have "unbalanced" triodes when viewed this way, and
some triodes are rather "peaky" like this one.
Shouldn't there be no peak if the tube was perfectly OK?
What would be the cause?
(BTW, data taken using $3.49 Cen-Tech DVOMs from Harbor Freight, one
used for each grid, and one for the plate via a switch)

I found my error; wrong neck (multiplier) for the giraffe.
Basically, in the range of interest; grid current does not affect the
set grid voltage.