More test about Slug Tuned Inductor
This page investigates some inductor I have got. As always one can
never find andy info about the coils and there is no manufacture label either so I have to investigate more.
All contribution to this page are most welcome
I have made 4 coils with different number of turns. I made 6, 8, 12, ans 28
turns.
There is a formula for coils I will use and I have the been using a LCR meter to measure the inductance of the 4 coils. The values are plotted
in excel to form a curve and from the curve I can calculate the A_{L} value. Formula : L (nH) = A_{L}*n^{2}
Where: L = inductance in nanohenrys A_{L} = inductance factor n = number of turns
This first diagram show the inductance with the screw-slug removed.
The red curve is made by excel and is a trendline. The inductance vary from 150nH to 3263nH.
The formula of the trendline is 3.2833 x ^{2.0681}
If you compare this formula to he first one you can see the similarity. The exponent is very close to 2 and the
A_{L} value will therefore be 3.28
The next diagram show the inductance with the screw-slug screwed to the bottom position.
The red curve is made by excel and is a trendline. The inductance vary from 457nH to 9113nH.
The formula of the trendline is 12.514 x ^{1.9734}
The exponent is still very close to 2 and the A_{L} value will therefore be 12.51
Conclusion: The ferrite slug core raise the A_{L} from 3.3 to 12.5, depending on how deep
it is screwed into the coil.
The tables below show the complete data. The position of the slug-core is in percent of the total lengt of the core. If there is no
core the value is 0% and if the complete core is screwed into the coil the value is 100%