[Milsurplus] hi volt choke testing questions

[Richard Brunner]

Re:
> Anyone have a quick and dirty way to test a power supply choke's
> inductance while running some current through it?
>
This is easily measured.  Use a center tapped power transformer with
adequate current capability, full-wave rectifiers, and connect the choke
from B+ to the transformer center tap with some series resistance.  This
puts both ripple voltage and dc on the choke.  Vary the input voltage, and
measure ac voltage across the choke vs dc current through the choke.  You
might need a blocking capacitor to keep dc out of the ac voltmeter.  Choke
inductance is then:

L = E / (I x 2pif) or E / (I x 753)

L =  choke inductance, Henries
E = ac voltage across choke, volts
I =  dc current through choke, amperes
2pif = 2 x 3.14 x 120 = 753

You will find that all chokes swing somewhat, maybe 2:1, but swinging chokes
swing more, maybe 5:1

Richard Brunner, AA1P

References:
"Measuring Inductance of DC Loaded Chokes," J. H. Ellison, W6AOI, QST, Feb.
1963, Pgs 1617.
"Know Your Filter Choke Coils," Harold Reed, W3EJP, CQ, Nov 1959, pgs 50,51.