Day: April 5, 2014

What we would like to know is how the troidal inductors works at not 100kHz, but at some practical frequencies, say, 7026kHz. So here comes our good old impedancen bridge.

The inductance should be around 116uH with 10 turns, which should turn out to be 5.12kohm at 7026kHz.

gnuplot> load "gnuplot11.txt"
Freq [MHz]=7.026
V1=3.69
V2=7.162
Cursor 1=1.6e-09
Cursor 2=0.0

vratio=1.94092140921409
phase1 [deg]=4.046976
phase2 [deg]=0.0

abs(gamma)=0.946050942356418
swr=36.0720099174506
cz={229.743717103124, 599.501591363751}

It is somewhat difficult to measure such high impedance with accuracy, because the system impedance is only 50ohm.

This is my first time to use troids, so let’s start from the very beginning. The core is FT-240-43 with AL=1.160uH/t^2.

The inductance is measured at 100kHz by changing the number of turns. The blue shows the measured values, and the red the values computed by AL*(turns^2).

Looks almost reasonable?