T200-6 Toroid Core Micrometal Powdered Iron

It compares well with alternate sources.

I understood the basics of passive filtration to cancel out RF that is plaguing the electrical grids all over the world. Power generation hasn't changed much since World War II. But the devices people now own sure have. Even if your stuff is benign, you can just bet your neighbors isn't. I own 3 unique devices from PS Audio called Noise Harvesters and you plug in the bottom and there's a large blue LED on the top. One capacitor filter RF or any high frequency noise until it fills and discharges this energy into the LED that discharges into harmless light. Energy cannot be destroyed. You can move it and cancel out into heat, or send it to ground. But what you can do is change it into a form less harmful, High Frequency RF and EMI into light. During the day, those things don't even flicker. When folks start coming home and turning on their PC's, LCD TV's, microwaves, almost any modern device with a switching power supply and my LED's flash like strobe lights. And I did nothing. So look you want to make your own filters also called baluns, have at it. If you get lucky and the capacitance and impedance right, wrap those wires just right with the right gauge, you will have some limited benefits. But engineers in labs have to get it just right and they get testing gear out the wazoo. Phase cancellation is the oldest trick in the book. Look at those awful sounding headphones. Twisted pair telephone wires have been around since right after the civil war!

Built a 17:1 CB balun for 1/2 wave antenna, WORKS GREAT!