Questions tagged [ferrite]
36 questions
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How does one read a ferrite datasheet?
Datasheets for ferrite materials are usually filled with incomprehensible graphs with greek letters. For example, Fair-Rite's 73 material:
What's a $\mu'_s$ and a $\mu''_s$? What do these numbers represent, and how can I use them in amateur radio?…
Phil Frost - W8II
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How to effectively test and interpret the "working range" of a ferrite core with a signal analyzer?
I have a couple of ferrite beads that are advertised as effective for suppressing conductive noise around 150kHz. I'm trying to monitor their actual performance with noise filtering.
In my set up I have a ferrite core which I made a number of turns…
GHGC
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9
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Importance of Ferrite Size in Coax Choke Balun
The question is quite simple: When making a coax choke balun, does the size of the ferrite matter, and if so, why?
I have seen design notes that say to use a single FT240-43 toroid for powers up to 400W, and then to use two stacked FT240-43 toroids…
M1GEO
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What's an appropriate core material for a loopstick antenna?
A loopstick antenna, if you don't know, is a coil of many turns around a high permeability core. They are frequently encountered in AM receivers and look like this:
This particular example is actually two antennas on one core.
What type of material…
Phil Frost - W8II
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7
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3 answers
Ferrite rod or core permeability determination
Is there a simple empiric way of determining the permeability (mhu) of a ferrite object (be it a ring, rod or any form)?
I've been thinking this for a rod: if I wind coils with different number of turns (same wire, just wind or unwind it) and…
Luca
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How to measuring ferrite core efficiency vs frequency
There is an unknown ferrite toroid. I would like to figure out whether it can be used in an audio transformer, or maybe in a 1:4 transformer on given HF frequency.
The experiment I came up with is following. I can wind a 1:1 transformer using this…
Aleksander Alekseev - R2AUK
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Can ferrite beads lower coax cable velocity factor?
For VHF and UHF, it seems reasonable to slip ferrite beads over a coaxial cable to act as a transmission line common mode choke. It also seems reasonable to use beads with the smallest diameter possible. This can lead to ferrite-over-cable lengths…
Chris K8NVH
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How to make a ferrite bar antenna for RTL-SDR?
I bought a RTL-SDR (blue one with little MCX antenna). I modified its Q branch, and can receive short wave radio with Degen 31MS antenna now.
For MW, Degen 31MS antenna has a ferrite bar antenna coupler to work with the internal antenna of the…
jac123
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7
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What is the maximum number of turns in a ferrite core used as a common mode choke?
Is there a way to estimate the maximum number of turns which can be used with a ferrite core used as a common mode choke?
It is known that the impedance of such a choke is proportional to the square of the number of turns and so there is a strong…
Chris K8NVH
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6
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Are some ferrites porous enough they should be protected outside?
I recently bought a couple of 61-mix toroids, and as usual I wrote the mix number on them before they become mystery parts. However, the ink soaked right into the ferrite.
I've left ferrites hanging out in the weather, getting wet and frozen without…
Phil Frost - W8II
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How to achieve highest Q-factor in inductors for 6-160m amateur bands?
When building filters for ham bands (direct sampling SDR frontend) - it is common to build filters using 2,6,10,12 material toroids. Are there any recent developments that offer lower losses / higher-Q in amateur bands? (6-160m)
Are there any other…
BarsMonster - R2AYN
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5
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How to meassure a ferrite using a VNA?
I want to measure a ferrite toroid using a VNA. I would like to classify it for a whole range of frequencies but if it's too complicated I'm OK to just pick one frequency.
I have 3 questions actually:
1: Is there a preferred test jig? My plan is to…
Jack0220
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Why are loopstick ferrite antennas commonly wound with Litz wire?
What is the advantage of using Litz wire to wind ferrite (loopstick) antennas? How much of an advantage in what characteristic does this type of wire provide? (over generic single strand enameled or insulated wire). How do different types of Litz…
hotpaw2
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How does a loopstick antenna actually receive signal?
Around 1970, I acquired a little transistor radio (powered by 4xAA cells, 6V) that had no external antenna. Inside the back panel (which opened to allow replacing the battery cells) one could see the loopstick antenna, just a ferrite rod with a lot…
Zeiss Ikon
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What causes differences in properties of ferrite cores from same material?
Why are the shapes of the impedance curves different for cores made of the same ferrite material?
The impedance (Z) of an inductor wound on a ferrimagnetic core is:
$$Z=j\omega L_s + R_s = j\omega L_0 (\mu_{s}^{'} -j\mu_{s}^{"})$$
where $L_0$ is the…
Brian K1LI
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