Spike
Gentlemen,
It is also worth noting that it's not the aircraft's voltage regulator in question here, more likely the radio equipment / avionics it's self!
As the starter is engaged, bus volts drop, the "equipment's voltage regulator" compensates and raises the voltage within the individual unit(s) and then with the sudden raise in voltage as the starter disengages is unable to react quickly enough to stop an over voltage situation and damage occurs!
HH