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It is as simple as the ferrite material you have is very lossy. There are much better ferrite materials to use at 1Mhz. With a proper core and litz wire, you can get the R under 1 ohm.

I am really getting a lesson here! I have a homemade coil of 40 turns on a Clorox bottle, so length about equals diameter, intended to be best Q possible. Q is 130 based on X and R reported by nanoVNA

My experience is in the AMBCB. Some have built air core coils with Qs reaching 2000. This was with two pieces of 640/46 litz wire in parallel. ?The best toroid Q I have seen is around 1500. These

You are correct, Jim, only for large inductances requiring lots of wire as you stated. But for us "average" inductances, still the air core would yield the highest Q. Dave - W?LEV

Oddly, not necessarily.? Yes, the same windings, with a core, will have higher L and lower Q, because of core losses. However, if you compare equal inductance and current handling ability, you might

What could be higher Q (lowest possible losses) than air or vacuum? Ferrite and powdered iron toroidal cores have a higher ?r which yields higher inductance per turn than free space, but there are

On 10/18/21 6:04 PM, Roger Need via groups.io wrote: > On Mon, Oct 18, 2021 at 11:59 AM, Gary O'Neil wrote: > >> Some may find this does-it-all calculator useful also. It is my go to site for >> all

Those interested in the theory behind the Duffy Calculator should read this link: https://owenduffy.net/blog/?p=18253 Roger

Gary, There are several calculators online like the one at toroids.info that have a common error. They assume that the initial permeability is the same with frequency. This is not true with ferrite

I just tried to verify pulses on my Bryman BM235, I didn't find any pulses, no matter what timebase I checked. I put 610k across the meter with the scope. Just tested again without the resistor, still

Just may have to try that later.Ran into this issue when measuring windings on some transformers and getting impossibly high numbers.? ? Dug out the old Simpson, and saw about what I was

That interesting! Maybe I'll be learning something here. What happens if you measure a 100k resistor with 10uf capacitor across it?

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