After some more study, it looks like the voltage regulator I have is probably working the way it was designed. It turns the alternator field off and on, and this causes the voltage to go up and down, and this causes current to go up and down as shown in the ammeter.

So, my next question is: are there any STC’s that allow for a better voltage regulation scheme? Like, something based on a modern concept like the transistor? Maybe something that smoothly modulates voltage and holds it to a steady value instead of pulsing up and down, hammering the mechanical part of the alternator and giving wildly varying spikes of voltage and current?

My alternator controller (voltage regulator) is Plane Power. After a lot of anguish, this problem has now actually been solved. My Tiger developed a bad case of noise in headsets. I took it to avionics repair experts and they diagnosed that my headset jacks were corroded, and intermittently shorting out. The problem showed up only when engine was running and was intermittent, due to mechanical vibration. The worst offender was jack on center console for handheld microphone. After an expensive repair and troubleshooting session, my intercom is now clean, no noise. I also see that my ammeter needle stays rock steady almost all of the time, and I see the normal, expected readings on voltage display of 13.9-14.1 volts. What I think was going on is that when the bus was being shorted out by the defective headset jacks, the voltage regulator thought that system voltage was low, so it was toggling the alternator field on and off. Wow, what a painful long exercise this was. Thanks for the help, glad to get this figured out and I hope nobody else has to go through this expensive and painful long duration exercise.