"Otherwise it is very hard to kill them."

Again, I hope you didn't miss the point. Most devices
do work *quite* well when operated within their design
specs (who would argue with that?). But THAT is just the
beginning ... SOMETIMES they treated improperly (like
during power up and power down conditions, operation over
temperature, TRANSIENT response, RF susceptability, etc).

I would like to state future reference that I have been
'round the bend with simple DC power supplies (since before
the 317 was invented even!). Back nearly two decades ago now
I even played a key role in solving a power supply 'dynamics'
problem for which I received a letter of commendation from
Dave Nurse (President at the time of Heathkit in St. Joseph -
Benton Harbor was just the mailing address). This stands as
testament to the solution of a nagging problem that had
plauged their SB-104 power supply for years and for which
*no* adequate solution had been found - until I encountered
the problem.

Ever heard of "charge storage" (excess carriers having been
injected into the base) effectrively occuring in the BE junction
of a bipolar transistor - a condition that can lead to excessive
turn-off delay times *after* a device has been driven far into
saturation?

All those who FINALLY got instructions on what mods to make
to get their Heath SB-104 power supplies to *stop* blowing
fuses (because the OVP circuit tripped) when coming out
of the 'Tune' position (or simply powering on the radio)
owe me thanks for finding 'the cure' to this nagging problem.

RF Jim (specializing not only in RF but DC as well)

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