[Amps] [BULK] - Re: 4000PIV rectifier CR104

[Steve Katz]

>Some hv diodes consist of several 1kv diodes in series.<

::Actually, *all* high voltage rectifiers are made this way; nobody's
invented an avalanche junction yet that can withstand more than about 1200v.
So, the "4 kV" rectifier is guaranteed to have at least four diode junctions
in series, and possibly more like 5-6-7-8 of them.

>If there were four  
then it would require a voltage of about 2.8 volts for all of them to
conduct.  
Many Volt Ohm Meters use a 1.5v battery for the low ohms scales and in this 
case  is not enough for conduction. If the meter has a higher voltage for 
higher  ranges, you might see conduction.
You can also connect the diode under test in series with a resistor and use

your 13.8vdc shack power supply as a higher voltage current source. If you 
used  a 1k resistor, you would expect to see about 11ma or so in the forward

direction  and hopefully zero ma in the reverse direction.
 
73,
K5GW<
 
::Yep, that's true.  Or, a curve tracer can usually be cranked up to several
kV, so you can look at the breakdown characteristic; or, you could use a
hipot tester or other source of high voltage, low current energy and crank
it up to see where the "4kV" rectifier breaks down under reverse bias.  A
rated 4kV device should break down somewhat above that, probably around
4.4kV.  Don't forget to current limit a reverse bias test to maybe 100uA or
so to prevent damaging the junctions. -WB2WIK/6