Hi, Mike -

On 1/28/2014 1:14 PM, amdx wrote:
On 1/28/2014 1:03 PM, amdx wrote:
I have beads* on a coax and want to know the R and the L.
I have measured the R at 3.85MHz, It is 3,350 ohms.

I will assume that Z is 3350 ohms at 3.85MHz.

I have also measured the phase shift, voltage leading
by 17ns. The period of 3.85Mhz is 260ns.

I want to calculate the impedance of the reactance.

The impedance of the reactance (alone) IS the reactance (itself).

Can anyone solve this for me?

I will try.

I would like to see the math, because I want to measure again
at 7.5MHz.

My first step was to find the phase angle, 23.5*.
Do we agree there?

We do (based on your numbers)...

Z = 3350 @ 23.5 degrees.

R = Z * COS(23.5) and
X = Z * SIN(23.5)

Therefore, R = 3072 ohms
and X = 1336 ohms

As a sanity check, Z = sqrt(R^2 + X^2) = 3350

Good!

HTH,

John S


Thanks, Mikek


* it is actually a bit more than beads. Years ago, we were sent a box of
ferrite potcores, the cores arrived broken. I slide 42 broke halves onto
a piece of RG59, and now I'm measuring it.


I had a thought, I measured the R by dividing Voltage by Current.
So that means, my current was limited my the L also. The Total impedance
is 3,350 ohms, this includes R and L.

Mikek