[volt-nuts] Fluke 343 arrived, trip behaviour
frank.stellmach at freenet.de
Thu May 10 22:27:51 UTC 2012
as far as I remember back 30 years, the behaviour of your 343A is
The trip behaviour on downranging or even on reducing the output setting
on the high voltage ranges is caused by the "crowbar driver" and "sink
supply". (see manual)
This circuitry protects the output driver transistors, because those
suddenly see excessive voltage if downranging occurs.
The protection circuit quickly discharges the capacitors following the
voltage doubler, and shunts the series voltage regulator transistors.
If the 343A stays stable on the high volatge ranges, if the setting is
not changed, everything is fine.
The 343A is a very nice unit for resolving 7 digits of voltage, although
it is not extraordinarily stable.
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