Iron Powder Cores

Kurt Speaks Out - Digital PDF Version - Download Now!

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KURT SPEAKS OUT - Digital PDF Version

Kurt's masterpiece contains 50 of Kurt Sterba's Kolumns from World Radio (1990 to 2006). 140 pages packed with sage advice, unusual antennas, and ham radio myths to avoid. Read, learn, and enjoy.

Included are unusual antennas: CCD, T2FD, OCF, Rattail Ver-Tee, G5RV, ZEPP, Loops and many others. Find out the real truth about antennas and STOP WASTING YOUR TIME and MONEY trying to get the lowest SWR! Download your copy and get educated by one of the experts – Krusty ole Kurt!!

Eham Review

Kurt N Sterba, sometimes known as “Krusty Olde Kurt” or “The Krusty One” and often as “The Masked Avenger”, is fearless in exposing antenna manufacturers who lie or use deceptive numbers to inflate the gain dB’s of their antennas. He also deflates those who use “new scientific breakthroughs” to explain the operation of their products. He pieces through the obfuscation of on-the-air antenna “experts” by explaining antennas, grounds, and feed lines in non-mathematical, simple English. His aim is to see that all understand the real basics of antennas, and are not taken in by the ever-prevalent, fine-sounding ad writers and other purveyors of false information.

Kurt wants you to know that downloading this work of art also entitles you to a free membership in KURTSKLUB, special product discounts, his oh-so-smart newsletter when he gets around to writing it, and more sage advice in his future books. You agree to keep your email box open, your mind free from commercial marketing hoop-la and let Kurt be your guide. Oh yea, spread the word, we need more members who seek true enlightenment like you!

Table of Contents

This version is published by Palomar Engineers, Inc.

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Iron Cores 150x150 - Iron Powder CoresIron powder cores are more stable than ferrites and do not saturate as easily so they are best for tuned circuits, filters, and high power inductors. They come in different “Mixes” for use at different frequencies. For best “Q” use the Mix specified for your frequency.To find the number of turns to give the desired inductance for your coil use the formula below:


Turns = 100 x iron core formula 300x14 - Iron Powder Cores

Toroid Dimensions

tcolorcode - Iron Powder Corestcore - Iron Powder Cores


To order specify core size and mix (e.g. T200A-2). Available in sizes that have µH per 100 turns shown in table.

All iron powder cores are special orders.  Please allow one week for shipment after order received.

The iron powder cores shown in the above tables are primarily used for either high power feed line chokes for common mode current reduction or for 4:1  and 9;1 very high power transmission line transformers.

For high power feed line chokes, choose the inside diameter of the iron powder core closest to the transmission line outside diameter and use 6-20 cores at the junction with the antenna feed.

For 4:1 (50/200 or 75/300 ohm) transmission line transformers in the range of 1.8-30 Mhz, select the size appropriate for the power level as follows:

T200A x 2 = 1.5KW

T300A x 2 = 2.5KW

T400A x 2 = 5KW

Use Mix 2 for all the above transmission line transformers.  Fully assembled and enclosed units are available for each of the power levels.  Click HERE for information.

4:1 transmission line transformers using iron powder cores are typically used for ladder line to 50 ohm coax connections

For .1 – 2 Mhz wide band transformers use Mix 26 which has a higher permeability and requires less turns to achieve a given inductance. Mix 2 has almost constant permeability from 1-30 Mhz.  Mix 26 has an initial permeability of 75 at .1 Mhz and gradually decreases to about 10 at 30 Mhz.  For high power AM broadcast range (.5-1.7 Mhz) transformer, use Mix 26 to reduce the turn count.

Minimum order for iron powder cores is $50  

Shipping on larger cores in quantity may be more than $10 – email/call for quote.