Aleph J illustrated build guide

[Ben Mah]

Best matching would be at the amplifier operating point. But that is not always possible so match as close as your tracer can get and call it a day.

You want to match Vgs for a given Iq and Vds.

Since you have an operating amplifier, you can measure those parameters.

 

[Zen Mod]

best to match them at Iq prescribed for exact circuit, measuring Ugs

if only lower level of Iq for matching is possible, that's also usable, matching "tracking" is pretty good, by experience

but, take that lower level isn't extremely lower than prescribed (in circuit)

you'll find plenty of info on Articles page of FW site

in short - everything as Ben said