[Boatanchors] Choke Info Needed

[J. Forster]

If you want to characterise a swinging choke, a single point measurement
at zero bias current is insufficient.

There are bridge configurations that allow inductance measurement vs.
current bias, just as there are to measure capacitance as a function of
bias voltage.

Some of the older GR bridges include this feature. I think the 1650s did
for example.

-John

==============

> Chokes are specified at no load in most catalogs. All the known ones Ive
> measured with a handheld LCR meter ar right on.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "J. Forster" <jfor at quik.com>
> To: "Mark K3MSB" <mark.k3msb at gmail.com>
> Cc: "List Boatanchors" <boatanchors at mailman.qth.net>; "Kenneth D.
> Grimm,K4XL" <grimm at sbc.edu>
> Sent: Thursday, October 08, 2009 6:36 PM
> Subject: Re: [Boatanchors] Choke Info Needed
>
>
>> Did you measure L as a function of current through the choke? It does
>> not
>> sound like it.
>>
>> -John
>>
>> ===============
>>
>>
>>> Well,  I checked again and came up the same info.
>>>
>>> I was looking for a 4-12 H 300 mA swinging choke, and a friend of a
>> friend said he had one, and I picked it up last night.
>>>
>>> It's about 18 ohms DC resistance,  and the inductance measures around
>>> 2H
>>> (using the bridge on my IT-28,  which isn't too bad surprisingly).
>>>
>>> Since inductance is inversely proportional to current in a swinging
>> choke, I don't think what I have is a swinging choke.
>>>
>>> Mark K3MSB
>>
>>
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>