When a digital meter encounters the "dirty" signal produced by a set of vibrating points in generator regulator, they often read out unintelligible gibberish instead of something usable. An analog meter will average the signal and provide a better reference. There's such a thing as being too accurate. I can search Ebay just about any day and find good condition Simpson analog meters that work well with DC generators. Ditto for dwell meters- - - -an analog meter is usually more useful than a digital, if an OEM points/condenser ignition system is involved.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!