[Milsurplus] hi volt choke testing questions

[Patrick Jankowiak]

Hello,

The Chicago BR-4 is a 50H 400mA modulation reactor weighing 73 
lbs. It is suggested to be used with a 500W transmitter. I think 
this one weighs about 50 lbs.

Patrick

Bob Camp wrote:

> 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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> 
>