[Milsurplus] hi volt choke testing questions

[Bob Camp]

Hi

A choke that will handle 500 ma at 43 H should weigh a ton. With an air 
gap it is sure to be a swinging choke.

One quick way to figure out the current rating:

If it's going to do any good at all as a choke rather than a resistor 
it's impedance at 120 ohms should be at least 10X it's resistance. Put 
another way you want it to have a Q of 10 to be of use as an inductor.

By more or less simple math that gives you an inductance of  1.2 H.

SInce the current rating is related to the wire they used there is no 
guarantee the part will handle 300 or 500 ma or that the part is 
running at it's limit when the inductance goes to 1.2 H. The only point 
is that there isn't a lot of reason to run it down past about 1.2 H.

	Enjoy!

		Bob Camp
		KB8TQ


On Jul 18, 2004, at 10:51 PM, Patrick Jankowiak wrote:

> Anyone have a quick and dirty way to test a power supply choke's 
> inductance while running some current through it?
>
> I have a weighty 95 ohm one that is 43H with no current. Like to know 
> how much with 200-500mA. It has a gap, so I am pretty sure it's not a 
> swinger, but I doubt it could still be 43H at 300mA.
>
> I checked the inductance by putting a 5K resistor in series with it 
> and a 20VAC power supply, adjusting the pot till the choke and 
> resistor each had the same voltage across them, and then measured the 
> resistance of the pot, substituted that for the reactive impedance of 
> the choke, and came up with 43H.
>
> Unfortunately I see no way to pass DC through the choke and also hook 
> up this AC power supply to it. Maybe in series?
>
> PJ
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