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Andy, The high loss R is, I believe, from the toroid ferrite material. This is why they are used for RF suppression, e.g. common mode choke baluns. K9YC has lots of material on this. See, e.g.,

That's what I see when I hook up my Harbor Freight special to a Tek scope! And on a Fluke meter as well. Kent

Agreed, but isn’t that R, divided into X at 1 MHz, going to give me Q? It will be terrible. I expected a toroid to offer higher Q than an air core…

Type J (75) was my first thought also, but his numbers, 1Mhz, 180uh and 200 ohms R, is a Q of 5 or 6 and I think that is much to low, unless he used some high resistance wire. To Kent, I have two

This cannot be a powdered iron core. I do not know of any powdered iron cores that have an AL value of 50,000 uH/100T. It has to be a ferrite core. Zack W9SZ

Check the units of your toroid chart - not everyone used the same scale, I've seen? uH/100 turns, mH/100 turns and others as uH/turns^2 L (mH) = AL(mH/turns^2) * 36 0.180 = AL * 36? -> 0.005

Here are sites that indicate the frequency range over which powdered iron cores are best applied, max Q. Powdered iron cores are designed for a specific frequency range to maximize the Q of inductors

The closest thing I see to that is the Amidon type J ferrite toroids. Useful frequency range is 1 to 15 MHz for type J. They don't specify a size exactly the same, but the FT87-J is the closest they

That 200 Ohms is not the same as a 200 Ohm resistor at any frequency other that 1 MHz. Again Impedance, not resistance.? Kent

Thanks, but I must disagree: the nanoVNA provides a resistance output as well as a reactance, and that is what I was reading to be 200 ohms at 1 MHz...

Not really resistance, but impdeance. Got a good old DC Volt Ohm Meter? Try that, but you see only 1 or 2 Ohms. Most of the Digital VOM;s are using pulses that are much like RF.So they are reading as

This thread inspires me to ask a question that is not directly about my nanoVNA: I have a toroid from a flea market that is blue, has OD = 0.875”, ID = 0.51”, and length = 0.3125”. I wrapped 6

You don't need anything other than the NANOVNAs to measure inductance as a function of frequency. Invoke the Smith Chart, and use the cursors to measure the L at any frequency within your sweep.

On Sat, 16 Oct 2021 Cliff <mailto:kd4gt.tn@...?subject=Re:%20%22Q%22%2C%20Coils%2C%20toroids%2C%20and%20guesswork%3F> wrote about an on line toroid calculator available at:

Some may find this does-it-all calculator useful also. It is my go to site for all things toroid. …. and even obvious and easy to remember and get to. Just type the following in the address bar of

I would find it interesting to see curves of L(uh) at different B field amplitudes. Such as with a weak antenna signal vs an amplifier output. I learned in my first AC circuits class that AsubL drops

I contacted the author of the program (Miguel Vaca) by email and sent him my suggestions and bug report. He has just released a new version which plots L versus frequency. Those designing toroid

Everything helps.. Thanks!

Jim, I agree with you. Here are some measurements of a 20M dipole. First measurement was made using calibrated range of 1 to 30 MHz. Next was using same calibration but "zooming in" to 13

Barring pathological cases