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Author Topic: Snap-on Ferrite Choke  (Read 516 times)

N0AKX

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Snap-on Ferrite Choke
« on: June 18, 2021, 05:21:58 PM »

Hi,

Are snap-on Ferrite chokes frequency specific? For example, if I search Ferrite chokes on Amazon, there are a lot of snap-ons but doesn't really mention frequencies...

Also, where do you put these chokes? Antenna end or Radio end and how many? Thank you.
Cho
N0AKX
« Last Edit: June 18, 2021, 05:25:57 PM by N0AKX »
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W9IQ

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Re: Snap-on Ferrite Choke
« Reply #1 on: June 18, 2021, 05:45:46 PM »

If your goal is to make a common mode choke, snap-ons are not the way to go. The idea behind a well designed common mode choke is to create a tuned circuit that exhibits a high resistance over the bands of operation.

What type of antenna and what bands ?

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KC9QBY

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Re: Snap-on Ferrite Choke
« Reply #2 on: June 18, 2021, 05:48:12 PM »

Before spend, a worthy must read:
http://k9yc.com/RFI-Ham.pdf

In my case mostly for RFI mitigation.  Reliable source in my experience:
https://www.kf7p.com/KF7P/Ferrite_chokes.html

Larger sizes are better investment since you can put more wire turns thru the snap-on, to the point of opting for toroids which can handle even more turns than snap-ones

Good luck and 73
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73,  Chuck  KC9QBY

N6YWU

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Re: Snap-on Ferrite Choke
« Reply #3 on: June 19, 2021, 10:54:09 AM »

My experience with cheap no-name snap-on ferrite chokes is that they don't do much to eliminate common mode noise.  They may help a little to quiet down DC converter wallwarts.  For feed lines, I would instead I would use several turns through mix 31 or mix 43 ferrite toroids at both the antenna end and the radio end of my feed lines (assuming you aren't on purpose using your feedline as part of your antenna).
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VA3VF

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Re: Snap-on Ferrite Choke
« Reply #4 on: July 15, 2021, 09:41:37 PM »

Buying/using ferrites of an unknown mix is a waste of time and money.

As for snap-ons, they are good if using on antennas/coax already installed. If installing a new antenna/coax, toroids are the way to go. There is also the durability factor of the snap-on plastic casing after some time subject to the elements.

As recommended already, read K9YC papers and purchase some FT240-31, FT240-43, and if you go into VHF consider some FT240-61 as well. For LF RX only I used a TDK N30 toroid.

As for a vendors, I've purchased from both Mouser and Digikey. Mouser is a little cheaper.
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