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 screwslug 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 screwslug 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 slugcore 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%
n = 6

Core position (%)

Inductance (nH)

0% (no core)

150

16%

170

33%

209

50%

285

67%

372

83%

440

100% (max core)

457


n = 8

Core position (%)

Inductance (nH)

0% (no core)

198

16%

217

33%

265

50%

341

67%

464

83%

657

100% (max core)

700


n = 12

Core position (%)

Inductance (nH)

0% (no core)

624

16%

640

33%

690

50%

837

67%

1091

83%

1425

100% (max core)

1701


n = 16

Core position (%)

Inductance (nH)

0% (no core)

982

16%

1056

33%

1265

50%

1650

67%

2154

83%

2659

100% (max core)

2957


n = 28

Core position (%)

Inductance (nH)

0% (no core)

3263

16%

3546

33%

4110

50%

5199

67%

6728

83%

8240

100% (max core)

9113



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