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 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.

Can anyone solve this for me?
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?

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.

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 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.

Can anyone solve this for me?
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?

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

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

On 1/28/2014 2:12 PM, John S wrote:
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

Thank you John.
Mikek

On 1/28/2014 3:18 PM, amdx wrote:
On 1/28/2014 2:12 PM, John S wrote:
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

Thank you John.
Mikek


It makes me feel good that I could assist. So, I thank you as well.

Cheers,
John S

On Tuesday, January 28, 2014 2:12:53 PM UTC-6, John S wrote:
Therefore, R = 3072 ohms
and X = 1336 ohms

Looks like it might be #77 ferrite material.

On 1/28/2014 3:50 PM, W5DXP wrote:
On Tuesday, January 28, 2014 2:12:53 PM UTC-6, John S wrote:
Therefore, R = 3072 ohms
and X = 1336 ohms

Looks like it might be #77 ferrite material.


It's a Ferroxcube 3B7 material.
Here's some info.
http://www.ferroxcube.com/Ferroxcube...asheet/3b7.pdf
Don't know how it compares to #77.

Mikek

On Tuesday, January 28, 2014 5:16:36 PM UTC-6, amdx wrote:
It's a Ferroxcube 3B7 material.

Overall, #77 is much better for HF with the resistance/reactance curves crossing at about 18 MHz. 3B7 is better for MF with the resistance/reactance curves crossing at about 1.5 MHz. The curves indicate that it should be more reactive than resistive at 3.8 MHz. Makes me wonder if the phase angle is actually 90-23.5=66.5 degrees?
--
73, Cecil, w5dxp.com

In rec.radio.amateur.antenna 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 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.

Can anyone solve this for me?
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?

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.

The real resistance should not change with frequency so just measure it
with an ohmmeter.

Total impedance is the square root of the sum of the squares of resistance
and reactance.

The phase angle will tell you if the reactance is inductive or capacitive.


--
Jim Pennino

On 1/28/2014 1:32 PM, wrote:
In rec.radio.amateur.antenna 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 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.

Can anyone solve this for me?
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?

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.

The real resistance should not change with frequency so just measure it
with an ohmmeter.

I'm not sure, it might change with frequency, this is a ferrite around a
wire, so the ohm meter won't work. It's loss in the ferrites.

Total impedance is the square root of the sum of the squares of resistance
and reactance.

The phase angle will tell you if the reactance is inductive or capacitive.

Yup, Eli the Ice man.
Mikek