Cont

There are two basic ferrite material groups:  (1) Those having a low initial permeability (μi) range from 20 to 850 µ (permeability) that are of the Nickel Zinc (NiZn) class (mixes 43, 52, 61); and (2) those having a high initial permeability (μi) above 850 µ are usually of the Manganese Zinc (MnZn) class (mixes 31, 73, 75, 77).

The Nickel Zinc (NiZn) ferrite cores (mixes 43, 52, 61) have low initial permeability (μi), exhibit high volume resistivity (high ohmic core surface resistance), moderate temperature stability and high ‘Q’ factors (figure of merit or level of operational performance) in the 500 KHz to 100 MHz range.

They are well suited for low power, high inductance, resonant circuits. Their low permeability factors also make them useful for broadband transformer applications (baluns, ununs, chokes). Nickel-zinc  ferrites have a higher resistivity and are used at frequencies from 2 MHz to several hundred megahertz. The exception is common mode inductors where the impedance of  NiZn material is recommended for use from 70 MHz to several hundred GHz.

The MnZn ferrite cores (Mix 31, 73, 75) have high initial permeabilities (μi), that are above 800 µ, have fairly low volume resistivity (low ohmic core surface resistance), and moderate saturation flux density. They offer high ‘Q’ factors for the 1 KHz to 1 MHz range. Cores from this group of materials are widely used for switching mode power conversion transformers operating in the 20 KHz to 100 KHz range. These cores are also very useful for the attenuation of unwanted RF noise signals (line or CM chokes) in the range of 2 MHz to 250 MHz. Manganese-zinc ferrites are generally used in inductor applications where the operating frequency is less than 5 MHz. The exception is common mode inductors where the impedance of MnZn material makes it the best choice up to 10 MHz.

What’s Different between Mixes? The “Mix” is the chemical formula of the iron oxide.  Ferrite is a actually a sintered, ceramic compound consisting of iron oxide and generally either of two types of ceramic (Google sintering for the definition):

  • Manganese-zinc (MnZn) is available as Mixes 31, 73, 75 and 77 (and others) and work well for common mode chokes
  • Nickel-Zinc (NiZn) is available as Mixes 43,  52, and 61, (and others) and are the preferred material for baluns and ununs.

Palomar Engineers uses mix 31, 43,  52, 61, 73, 75 and 77 for most applications from RFI/EMI common mode suppression; multi-ratio toroid baluns and ununs; and sleeve baluns for line isolation.  Each mix number has a measurable permeability and suggested frequency range for certain applications.

Table 1. gives our recommended applications for various mixes and effective frequency ranges

Mix # Material Initial Permeability μi RFI/EMI Common Mode Suppression Range Tuned Circuits – Coil Wide Band Transformer (Balun & Unun)
31  (1) MnZn 1,500 1-300 MHz 1:1 only, <300 MHz
43 (2) NiZn 800 25-300 MHz < 10 MHz 3-60 MHz
52 (6) NiZn 250 200-1000 MHz < 20 MHz 1-60 MHz
61 (3) NiZn 125 200-1000 MHz  <100 MHz 1-300 MHz
73 (7) MnZn 2,500 < 50 MHz < 2 MHz <10 MHz
75/J (4) MnZn 5,000 150 KHz – 10 MHz  < .75 MHz  .1-10 MHz
77 (8) MnZn 2,000 200 kHz – 15 MHz <4 MHz .5-8 MHz

Table 1.

Notes:

(1) Mix 31 excellent for 1-10 MHz common mode suppression, then performs similar to 43 up to 250 MHz. It is NOT recommended for multi-ratio impedance transformers (baluns/ununs) due to material characteristics and power handling capability but OK for ham radio 1:1 feed line chokes. Its Curie temperature is >130 C (temperature above which the magnetic properties begin to fail and permanently destroys the usefulness of the core). Mix 31 is available in TOROIDSSLIP ON BEADS, and SNAP ON SPLIT BEADS

(2) Mix 43 is excellent for common mode chokes from 25-300 MHz, Use Mix 31 below 10 MHz for higher choking impedance. Curie temperature >130 C..  Mix 43 is available in TOROIDS, and SLIP ON BEADS

(3) Mix 61 will withstand high power in multi ratio (2:1, 4:1, 9:1) impedance transformers (baluns/ununs). Currie temperature > 300 C.  Mix 61 is available in TOROIDSSLIP ON BEADS, and SNAP ON SPLIT BEADS

(4) Mix 75 (also known as Mix J) Beads only. Go to Palomar Engineers link above for applications.

(5) There’s no footnote 5.

(6) Jerry Sevick, W2FMI’s broadband transformers (baluns/ununs) used a permeability of 250 (Mix 52). The F240-52 ring toroids are ideal for replicating his designs. For a free archived download of his book, “Transmission Line Transformers Handbook, 48 Improved Designs”, paste this link into your browser: Ham Radio Transmission Line Transformers Handbook

(7) Mix 73 is only available in small bead size from Palomar but exists elsewhere in standard sizes, for larger inside diameter requirements use Mix 77.

(8) Mix 77 has a much lower permeability of 2,000 instead of 5,000 like mix 73. I cut and pasted the relevant data for 77 mix into Table 1 that I copied from Fair Rite.

General Comments On Frequency Ranges And Application

When selecting a mix to use for tuned circuits or broadband transformers, the frequency range should allow for operation in the INDUCTIVE range of the ferrite mix frequency curve.  For best results use the proper mix with a RESISTIVE-dominant range for RFI/EMI suppression at the fundamental RFI frequency.  Additionally, Mix 31 is only appropriate for 1:1 impedance (CM) transformers and for RFI suppression from 1-300 MHz; it should not be used for <1:1 or > 1:1 impedance transformers as the material resistivity is high when used above 5 MHz. 

We have experienced excellent RFI common mode suppression under 5 MHz with mixes 75 and 77 when using multi-turn toroidal topology (translated, 1:1 Guanella current balun. Transformer construction will be covered later.)

Part 2 will continue with more details on core selection and winding with regards to frequency, and power handling capability, plus enclosures, plus lots of other useful stuff.




Dave Arrich AD6AE

In 1957 after acting on a whim, I discovered the answer to, “I wonder what the inside of a light socket feels like.”  It was love at first bite and has been my major focus since. I repaired my first radio at age ten and opened my radio & TV repair business – obviously on a very small scale – at age 13.  I was like a sponge and sought out independent repairmen who would tolerate a kid watching over their shoulder, asking lots of questions and relieving them of their inventory of old black and white TV sets.Antennas and transmission line theory has been a passion of mine from the beginning of my amateur involvement in 1972 after my Elemer and coworker at Fort Meade, Md. suggested that I try it.  From my first morse character to Extra only took a year.  Becoming proficient at copying 20 wpm with a stick is all that held me back.

In the spring of 1974, I got my novice license – WN3YSQ. Late that fall, my Elmer and I went down to the FCC office in Washington DC, where we were greeted by “Mr. Personality” who barked out some instructions and an hour later, we happily strutted out with our Extra tickets. My call was now WA3YSQ. In 1980, I completely lost interest and put my station in storage for the next 40 years.

When I returned to the hobby three years ago, my current vertical antenna required winding a non-standard ratio Unun that used an unconventional winding method. I had no idea on earth what I was doing or even how it worked. But, I got the parts and wire, wound it and it worked very well. I needed to know why. Thus began my search thru the sparsely published art of transmission line transformer theory and design.

I’ve since amassed a lot of information and have been corresponding with two professional RF Engineers, G8JNJ and VK2OMD, who have greatly aided my understanding of RF transformers. In the upcoming months, I’ll be sharing some of the fun stuff that I’ve learned in antenna types, operation, refinement and more specifically, basic matching transformer design and construction. I’ll include very simple, math to get you in the ballpark; explanations on how they work, what to use for what; why they’re made that way, how to test them to weed out the bad ones; those expensive commercial units with nice stickers that appear to work well but actually don’t and why. I’ll also include reputable sources for the components for those who may be so moved to experiment. 73’s all. Dave AD6AE




N6FRG Pico Balloon Launched




Marconi Day, 150th Anniversary

Effort to Save Marconi Towers in Canada – Public Invited to Vote on Project

04/10/2025

Article Courtesy Of ARRL

Photo Courtesy Of The SWLing Post

There’s an effort underway to save some of Marconi’s original towers, and an online poll is open for people to vote on it being a restoration project through the “Next Great Save” project from the National Trust for Canada.

Some of Marconi’s first messages were received and transmitted using the Battle Harbour Marconi Towers, thought to be the last of their kind standing in North America. News of Admiral Robert Peary’s 1909 North Pole expedition was transmitted by these towers. After 100 years, the twin towers are in need of repair.

To honor 150 years since Marconi’s birth, there are a number of events planned around the world to observe Marconi’s birthday and International Marconi Day.

In the United States, from the Port of Baltimore, Maryland, the Nuclear Ship Savannah Amateur Radio Club will operate K3S on April 26 from 1330 – 2100Z. Check spotting networks for frequency. See QRZ.com info for Savannah Award qrz.com/db/k3s. A QSL card is available by contacting Ulis Fleming, 980 Patuxent Rd, Odenton, MD 21113.

The Great South Bay Amateur Radio Club in Babylon, New York, will operate W2GSB from the Babylon Village Historical Society Museum for Marconi Day on April 26, 1300 – 2030Z. Frequencies include 28.340, 21.250, 14.246, and 7.245 MHZ.

Photo Gallery




QSO Parties For April 19-20

Click on the Links for each state information http://nebraskaqsoparty.com http://miqp.org http://va3cco.com http://quebecqsoparty.org




Another Three State QSO Parties Slated For The Weekend Of April 12th & 13th

List http://www.newmexicoqsoparty.org, http://www.gaqsoparty.com, http://www.radioclub-carc.com




Visalia DX Convention this Weekend

Click on the Link below for more information on the convention

Convention LINK http://dxconvention.com




State QSO Parties for April 5th and 6th Missouri, Mississippi, Louisiana

Follow these Links for additional information on each state QSO party http://w0ma.org

arrlmiss.org

laqp.org




Ham Cram April 19th




Minden NV Swap

Radio Ranch Swap Get Together
June 7 2025

Rain or shine event | 7:00 am

This is a free event

N7RCA Annual Electronics Swap Meet/Hamfest
his masters voice

 No food or drinks available – Bring chairs and tables

Temps in the day time can range from mid 60’s to mid 80’s Nights in the 60’s to low 40’s

Bring a hat and sunscreen, the Elevation is 5000 feet of clear blue open skies.

Notice: This event is a non-commercial event, not for profit. N7RCA is not a party to any sale, claim or warranty from attendees. Owner is not responsible for any loss, damages or injury while on the property. Attend at your own risk. if you don’t agree to these terms please do not attend.