On Jan 21, Ted, KN1CBR posted regarding a suspected supply transient
problem damaging his K2. This post encouraged me to check the response
of different power supplies to a load step from high to low load. This
is a situation where the internal regulator in the supply can
potentially overshoot due to one or a combination of several factors:
poor regulator design, DC lead inductance, DC lead resistance and others.
In general most name-brand supplies have minimal overshoot and decent
regulation, but some very inexpensive switching regulators have terrible
performance. I would never suggest running expensive electronics on a
cheap unquantified switching power supply...or linear supply for that
matter. A common failure mode for linear regulators when overloaded or
overheated is shorting of the pass device. Without a crowbar circuit
installed this will of course put full unregulated voltage at the output
terminals. Conversely, failure of a power device in a switching
regulator will cause the output to drop to zero.