[Boatanchors] Choke Info Needed

[J. Forster]

Characterizing is measuring the incremental inductance as a function of
bias current. That is essential information to calculate the impedance of
the choke vs. current and hence the regulating effect when used as a
swinging choke.

Apples and apples.

-John

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



> Characterising is not the same as confirming the static inductance. Dont
> mix
> apples and oranges.
>
> Carl
>
>
> ----- Original Message -----
> From: "J. Forster" <jfor at quik.com>
> To: "Carl" <km1h at jeremy.mv.com>
> Cc: "Mark K3MSB" <mark.k3msb at gmail.com>; "List Boatanchors"
> <boatanchors at mailman.qth.net>; "Kenneth D. Grimm,K4XL" <grimm at sbc.edu>
> Sent: Thursday, October 08, 2009 7:35 PM
> Subject: Re: [Boatanchors] Choke Info Needed
>
>
>> 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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>>>
>>>
>>
>>
>
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