Radio Frequency (RF) Iron Powders

General Material Properties

Material Reference
Permeability
Powder Type Temp Coef of Perm
(+ppm/C°)
Density
gm/cm
Max Frequency
(MHz)
Relative Cost Color Code
Toroid
-0 1 Phenolic N/A N/A N/A 1.2 Tan/Tan
-1 20 Carbonyl Iron 280 6.4 10 3.6 Blue/Clear
-2 10 Carbonyl Iron 95 5 45 2.0 Red/Clear
​-3 35 Carbonyl Iron 255 6.5 5.0 3.2 Gray/Clear
-4 9 Carbonyl Iron 280 5.0 17 5.1 Blue/White
-6 8.5 Carbonyl Iron 35 5.0 55 5.1 Yellow/Clear
-7 9 Carbonyl Iron 30 5.0 50 3.8 White/Clear
-8 35 Carbonyl Iron 255 6.5 5.0 2.7 Yellow/Red
-10 6 Carbonyl Iron 150 4.9 83 5.6 Black/Clear
-15 25 Carbonyl Iron 190 6.4 7.0 3.2 Red/White
-17 4 Carbonyl Iron 50 4.8 170 3.7 Blue/Yellow

 


 

  • ‐2, ‐4, ‐6 & ‐7 Materials: These are the most popular carbonyl iron mixes. They will provide High Q up to 40 MHz and the most popular for amateur radio and variety of other communication applications. They are also useful for moderate band transformers in the 200 to 400 MHz frequency range
  • ‐1, ‐3, ‐8 & ‐15 Materials: These materials are annealed carbonyl irons providing the highest carbonyl permeability. They are useful for high Q applications below 1 MHz and will provide the broadest band transformers covering a typical range from 50 to 500 MHz.
  • ‐10 & ‐17 Materials: These materials are the highest frequency carbonyl irons. They will provide high Q up to 150 MHz and are a popular material for cable television applications. They will produce moderate band transformers covering 400 to 700 MHz.
  • ‐0 Material: This is a non‐magnetic material. It provides a solid winding form for winding air coils. It has excellent temperature stability and will provide high Q up to the highest frequencies. It is also useful for moderate band transformer applications covering a typical range from 600 MHz to 1 GHz.

 

Initial Permeability (µi) vs. DC
Magnetizing Force

Percent Initial Permeability (%µi) vs.
DC Magnetizing Force

Percent Initial Permeability (%µi) vs. Peak AC
Flux Density 

Initial Permeability (µi) vs Frequency (Hz)

BH Curves

Material Frequency Range