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Questions tagged [ferrite]

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6 votes
1 answer
374 views

Why do 9:1 ununs use type 2 material for the core?

I do not understand how a 9:1 unun wound on a T200-2 works. I understand the transformer voltage and current ratios. I have wound several toroid chokes and 49:1 ununs and know how they work. What is ...
Dereck's user avatar
  • 629
2 votes
0 answers
81 views

trying to get a passive AM bar antenna to work

I pulled a nice big external AM ferrite bar antenna off a working stereo. 5.5" long. it has 4 wires coming off of it. red must be the main wire, because checking that with an LCR meter connected ...
Fyodor's user avatar
  • 31
2 votes
1 answer
525 views

What are these extra wires coming out of my ferrite rod antenna

From my understanding a ferrite rod antenna is simply a length of wire wrapped around a ferrite rod. A wire will sticks out of each side of the rod, one is ground and one is the main receiver. I ...
Dan's user avatar
  • 311
4 votes
1 answer
677 views

60kHz WWVB receiver help

I have built a large ferrite loopstick antenna based off this video. I live in Washington state and am trying to receive and decode WWVB. I can get my antenna to resonate at 60kHz with ~700 pF of ...
Max686's user avatar
  • 41
6 votes
1 answer
206 views

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-...
BarsMonster - R2AYN's user avatar
0 votes
0 answers
36 views

Ferrites losses calculation

I am new on RF design. I would like to know more about ferrites. I am looking for information about how to calculate ferrite losses and saturation points for a given application. I also would like to ...
Drod's user avatar
  • 101
3 votes
1 answer
374 views

Using PVC coated solid-core wire for a small number of turns on toroid

I'm researching making my own 49:1 unun using an appropriate mix ferrite toroid and some reasonable gauge solid-core wire. (This is for an experimental HF end-fed antenna, though this detail probably ...
user avatar
2 votes
1 answer
2k views

Core mix preferences for a balun (or unun) vs a choke

Was watching a YouTube video a little while ago and an engineer from Palomar engineers mentioned that using Mix #31 cores for balun construction wasn't ideal. He went on to mention that Mix 31 (or 43 ...
t252's user avatar
  • 697
3 votes
1 answer
144 views

Ferrite choice for fan dipole

I am intending to build a two element fan dipole for 80 and 20m. How should I go about choosing a ferrite toroid and number of windings for the balun, to operate effectively over such a range of ...
RoadieRich AE8RL's user avatar
1 vote
3 answers
179 views

Can ferrite rod antenna be made out of the choke?

I'm reading the instructions on preparing the ferrite rod antenna. If I understand it correctly it is matter of building an LC circuit. My question is: Can the ferrite rod antenna be built using a ...
Hieronim's user avatar
  • 111
5 votes
1 answer
716 views

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: ...
Jack0220's user avatar
  • 371
3 votes
3 answers
810 views

Is this true about ferrite loop antennas?

There is an article on wikipedia about loop antennas. It shows like an AM radio's antenna with the ferrite rod and says this: This greater conductance channels thousands of times more magnetic power ...
pgibbons's user avatar
  • 444
5 votes
1 answer
583 views

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 ...
hotpaw2's user avatar
  • 13.5k
5 votes
1 answer
1k views

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 ...
Zeiss Ikon's user avatar
  • 4,127
0 votes
2 answers
106 views

Can a slinky serve as a ferrite core and if so, is there a prefered configuration? [closed]

Ferrite cores ain't cheap when you start talking about the 3 inch ID ones. I can see em for like 40 and 50 bucks.... I don't see why I can't just ground a slinky or something.
NonYaBidnezz's user avatar
3 votes
2 answers
2k views

How do you calculate the number of turns for a common mode choke?

I want to build a common mode choke for my end-fed wire antenna, using turns of coax through an FT140 or FT240 ferrite. I can find various finished products for sale, but I want to make my own. I ...
Joel Clark's user avatar
9 votes
2 answers
312 views

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 ...
GHGC's user avatar
  • 93
9 votes
2 answers
3k views

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 ...
M1GEO's user avatar
  • 223
3 votes
1 answer
331 views

How does this 3 dB splitter/combiner work?

I'm having difficulties to understand how does this circuit work: Apparently T1 is a regular 50 Ohm to 22.2 Ohm autotransformer. Turns ratio 2:3 gives a 0.66**2 impedance converation. Since the load ...
Aleksander Alekseev - R2AUK's user avatar
3 votes
0 answers
1k views

9:1 unun material and power loss

I need to build another 9:1 unun and I start searching for my toroids... (I have build 2-3 something like 4 years ago)... In parallel I checked on Google about the correct toroid etc so I found 2-3 ...
OHTO's user avatar
  • 149
4 votes
1 answer
211 views

Commercial Loopstick Antenna Manufacturers?

I am an electrical engineer working on a product that needs a loopstick antenna. I had thought that AM radios were so commoditized that I'd be able to find an off-the-shelf vendor. However the closest ...
Aaron's user avatar
  • 41
5 votes
0 answers
141 views

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 ...
Brian K1LI's user avatar
  • 7,878
0 votes
0 answers
37 views

UHF cubical quad VNA analysis interpretation (part2)

This is the follow up to: UHF cubical quad VNA analysis interpretation This is a S21 and S31 analysis of an oversized 385 Mhz 50 Ohm to 90 Ohm balun between 100 Mhz and 600 Mhz I tested phase ...
rodv92's user avatar
  • 173
6 votes
1 answer
2k views

How do I evaluate and use a toroidial core for my HF double-balanced mixer?

Last year, I planned to make a double-balanced mixer covering the entire 3-30 MHz band as an upconverter for my RTL-SDR receiver, mainly for learning RF circuits and ham radio. Naturally, it requires ...
比尔盖子's user avatar
7 votes
1 answer
4k views

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 ...
Aleksander Alekseev - R2AUK's user avatar
7 votes
2 answers
526 views

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 ...
Chris K8NVH's user avatar
  • 1,042
0 votes
1 answer
268 views

Can I make ferrite paint? Will it shield my antenna from my roof?

I have a 3 element vertical Yagi mounted on a rotator, and in one direction the roof of the house gets pretty close and messes up the SWR a bit. If i mash up a few type 43 material ferrite cores and ...
Andrew's user avatar
  • 3,693
7 votes
1 answer
1k views

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 ...
jac123's user avatar
  • 73
5 votes
3 answers
2k views

Is this the Correct Ferrite Core to Reduce RFI as a Common Mode Choke?

I have a Flex 3000 connected via RG-11 coax to a inverted V fan dipole tuned for 40m and 20m on my roof. I have an "ugly" balun up on the mast by the antenna. I further have the feed-line going into a ...
Etep - VE6ETP's user avatar
7 votes
2 answers
2k views

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 ...
Chris K8NVH's user avatar
  • 1,042
1 vote
1 answer
290 views

Need a ferrite suppression material for choking 15 kHz to 60 kHz

Electric fence RFI is ruining reception on our VLF lightning receivers, and we need a material to place around neighbors' fence wires to suppress the noise being radiated. Preferably, a split bead, ...
Mike Waters's user avatar
  • 8,071
2 votes
2 answers
2k views

What core material do I need to construct a 1:1 unun for 6M?

I want to build a 1:1 unun for a 6M dipole. Power level 100W. What core material should I use?
Bruce A Friend's user avatar
7 votes
3 answers
1k views

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 ...
Luca's user avatar
  • 329
6 votes
1 answer
593 views

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 ...
Phil Frost - W8II's user avatar
1 vote
1 answer
1k views

Do a toroid's specs matter much in an antenna matching transformer?

I'm getting started with my first (very basic) HF rig and for convenience and the experience I'd like to try an End Fed Half Wave antenna. Typical designs for a "matchbox" in this case include ...
natevw - AF7TB's user avatar
2 votes
1 answer
197 views

Ferrite Rod Price Differences

We are trying to make a VLF geophysics device for our graduate project and we need two ferrite rod antennas (desired length is 6"). Searching on the internet, we have found two ferrite rod suppliers. ...
ecabuk's user avatar
  • 123
16 votes
2 answers
5k views

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 ...
Phil Frost - W8II's user avatar
8 votes
1 answer
5k views

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 ...
Phil Frost - W8II's user avatar