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:[EMAIL PROTECTED]
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 <[EMAIL PROTECTED]>
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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