R: [Elecraft] Winding my first toroid on my K2 kit

[Jack Smith]

Paolo:

Inductance is proportional to number of turns squared, so two inductors, 
otherwise equal. If one has 10 turns and one with 20 turns, the inductor 
with 20 turns will have (20/10)^2 = 4 times the inductance of the 10 
turn one. This assumes all the flux links all the turns, which is 
usually a decent assumption for toroid with high permeability.

Jack



paolo gramigna wrote:
> Hi,
> In order to check the accuracy of my bridge, I measured the colour based
> inductors, and the measured values closely matched the expected ones, when
> measured on my HP 4260A.
>
> In the meantime, I winded up RFC11, 20 turns. Instead of the published
> 100uH, I measured a value of 270, with a Q of 5.
>
> There is a note on the manual cautioning NOT to match the published
> inductance, but to stick to the published number of turns. I wonder what it
> means...
>
> Then I made another consideration... RFC11 has 20 turns, and the published
> value is 100uH. Then RFC14 has 10 turns and it is published at 18 UH. There
> is no proportion between those published values, on my humble opinion...
> While the two measured values (I rechecked them to the utmost accuracy
> available with my ancient instrument) were 270 uH and 130uH; half the turns,
> half the inductance. And that makes sense... While the accuracy of my HP
> 4260A seems confirmed by the solenoidal "green body" inductors. There is
> something missing there....
>
> Cheers,
> IK4YNG Paolo
>
>  
>
> -----Messaggio originale-----
> Da: Arie Lukkassen [mailto:arie_lukkassen at yahoo.com] 
> Inviato: lunedì 25 settembre 2006 14.11
> A: paolo gramigna
> Oggetto: Re: [Elecraft] Winding my first toroid on my K2 kit
>
> Some are used as rf chokes and the value has a big tolerance. the toroid
> material might be the culprit b because the wiring supplied does not vary
> much in parameters. 
>
>
>
>
> Why do not measure some of the  colour banded inductors as a reference and
> the special supplier inductor for the PLL. This is one is very important.
>
> Rgds
> Arie 
>
> --- paolo gramigna <paolo.gramigna at controllo.it>
> wrote:
>
>   
>> Hi all,
>>
>> I'm arrived at page 53 of the manual, and I'm making my first toroid. 
>> I followed the instructions, and then out of curiosity I tried to 
>> measure the inductance, using my old HP 4260A. I know that I'm not 
>> supposed to match the indicated inductance, and that I should stick to 
>> the published turns count; in fact I was just willing to give a try to 
>> the HP 4260A, the least used instrument in my lab.
>>
>> Well, it ended up indicating a value of 160 uH, not
>> 18 uH as supposed. So I
>> tried to measure the value on another bridge I had there by chance, 
>> and ended up with a very similar value.
>>
>> So I tried the HP 4260A on the solenoidal RFC (the green bodied) and I 
>> found values very similar to what I expected.
>>
>> I know that i'm doing something wrong, but I cannot understand what's 
>> my mistake....
>>
>> Cheers,
>>
>> IK4YNG Paolo
>>
>>
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