Questions tagged [ferrite]

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4
votes
0answers
46 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 ...
5
votes
2answers
75 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 ...
0
votes
1answer
105 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 ...
7
votes
1answer
219 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 ...
5
votes
3answers
304 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 ...
6
votes
2answers
418 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 ...
1
vote
1answer
101 views

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

Electric fence RFI is ruining reception on our ELF lightning receivers, and we need a material to place around neighbors' fence wires to suppress the noise being radiated. Preferably, a split bead, ...
2
votes
2answers
378 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?
5
votes
2answers
293 views

Ferrite rod 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 ...
6
votes
1answer
149 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 ...
1
vote
1answer
675 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 ...
2
votes
1answer
115 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. ...
12
votes
2answers
3k 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 ...
7
votes
1answer
3k 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 ...