K2 Toroids not measuring correct inductance?

[rhapak]

Hi all!
In the K2 manual it says to wind the toroids with the amount of turns specified and not to alter the windings to get the inductance specified in the parts list.
I notice that many of my toroids do not measure near the stated inductance in the parts list but are wound with the specified amount of turns and would just like to know why??

Thanks in advance,
Rod
VA3 ZVT

[Eric Swartz - WA6HHQ]

Stick with the correct number of turns. The inductance listed is a
nominal calculated value and will vary from core to core, and with the
frequency used to measure the inductance.

We also see a wide variance in inductance measurements between different
instruments based on their differing test frequencies.

It -is- important that you confirm you are using the correct core, color
etc.

73, Eric


On 6/1/2011 10:20 AM, rhapak wrote:

> Hi all!
> In the K2 manual it says to wind the toroids with the amount of turns
> specified and not to alter the windings to get the inductance specified in
> the parts list.
> I notice that many of my toroids do not measure near the stated inductance
> in the parts list but are wound with the specified amount of turns and would
> just like to know why??
>
> Thanks in advance,
> Rod
> VA3 ZVT
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K2-Toroids-not-measuring-correct-inductance-tp6427961p6427961.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[Ingo Meyer, DK3RED]

Hello Rod,

> In the K2 manual it says to wind the toroids with the amount of turns
> specified and not to alter the windings to get the inductance specified in
> the parts list.
> I notice that many of my toroids do not measure near the stated inductance
> in the parts list but are wound with the specified amount of turns and would
> just like to know why??

Do not count the windings. Wind it (like 7000 K2-builder before) and it's right.
--
73/72 de Ingo, DK3RED - Don't forget: the fun is the power!
        www.qrp4fun.de - [hidden email]
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[Ingo Meyer, DK3RED]

Hello Rod,

> In the K2 manual it says to wind the toroids with the amount of turns
> specified and not to alter the windings to get the inductance specified in
> the parts list.
> I notice that many of my toroids do not measure near the stated inductance
> in the parts list but are wound with the specified amount of turns and would
> just like to know why??

Ups (measure not count)!

Do not messuare the windings. Wind it (like 7000 K2-builder before) and it's right.
--
73/72 de Ingo, DK3RED - Don't forget: the fun is the power!
        www.qrp4fun.de - [hidden email]
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[Jim Brown-10]

On 6/1/2011 10:20 AM, rhapak wrote:
> I notice that many of my toroids do not measure near the stated inductance
> in the parts list but are wound with the specified amount of turns and would
> just like to know why??

In addition to the tolerance variations Eric mentioned, the measurement
frequency also matters.  Ferrite and iron core materials do not exhibit
pure inductance that is constant with frequency, there's also resistance
from the core, and capacitance between the turns and the core, and
between turns.

There's a discussion of this in my RFI tutorial, which has been
incorporated into recent versions of the ARRL Handbook.  While my work
has been dedicated ONLY to ferrite materials, powdered iron cores must
follow the same laws of physics, but with different physical parameters
-- that is, different values of mu, R, and C versus frequency.

73, Jim Brown K9YC
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[Jack Smith-6]

I recently measured, using lab  grade equipment, 16 powdered iron toroid
inductors of approximately 2uH and 16 of approximately 9 uH, at a fixed
frequency. Details can be seen at
http://www.cliftonlaboratories.com/may_2011.htm under 15 May 2011 entry.

The purpose of the exercise was to assess the inductor-to-inductor
variation, recognizing that 16 inductors, wound by the same person, and
from one batch of cores, is likely to show less variation than if 16
different builders wound one inductor each, and if the cores were from
random manufacturing batches.

The inductance spread was 10% for the 2uH parts and 8% for the 9uH parts.

Jack K8ZOA


On 6/1/2011 1:25 PM, Eric Swartz - WA6HHQ, Elecraft wrote:

> Stick with the correct number of turns. The inductance listed is a
> nominal calculated value and will vary from core to core, and with the
> frequency used to measure the inductance.
>
> We also see a wide variance in inductance measurements between different
> instruments based on their differing test frequencies.
>
> It -is- important that you confirm you are using the correct core, color
> etc.
>
> 73, Eric
>
>
> On 6/1/2011 10:20 AM, rhapak wrote:
>> Hi all!
>> In the K2 manual it says to wind the toroids with the amount of turns
>> specified and not to alter the windings to get the inductance specified in
>> the parts list.
>> I notice that many of my toroids do not measure near the stated inductance
>> in the parts list but are wound with the specified amount of turns and would
>> just like to know why??
>>
>> Thanks in advance,
>> Rod
>> VA3 ZVT
>>
>> --
>> View this message in context: http://elecraft.365791.n2.nabble.com/K2-Toroids-not-measuring-correct-inductance-tp6427961p6427961.html
>> Sent from the Elecraft mailing list archive at Nabble.com.
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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