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Author Topic: Proper way to use mix 31 rings x2  (Read 300 times)

GREYLINE

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Proper way to use mix 31 rings x2
« on: October 04, 2022, 12:31:03 PM »

I installed one 3.0" ID mix 31 ring on the AC line close to my internet router. It seemed help, but it's not quite there yet. I can't add any more turns because they would overlap one another, so I thought maybe adding another 3.0" ring would solve this RFI issue.

Question: Do I butt up both rings together and wrap my turns through both of them OR do I seperate the rings having several turns on each ring with a small length of AC line between them?


Thanks :)
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W1VT

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Re: Proper way to use mix 31 rings x2
« Reply #1 on: October 04, 2022, 12:36:52 PM »

http://www.karinya.net/g3txq/chokes/type31.jpg
Frequency response of one, two, or four FT-240-31 cores.
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AE0Q

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    • AE0Q Amateur Radio
Re: Proper way to use mix 31 rings x2
« Reply #2 on: October 04, 2022, 12:43:18 PM »

Question: Do I butt up both rings together and wrap my turns through both of them OR do I seperate the rings having several turns on each ring with a small length of AC line between them?   Thanks :)

Wrap the line around one, then a few inches of line and warp it around the 2nd core.

http://www.audiosystemsgroup.com/RFI-Ham.pdf

See page 14 (and others, of course) :-)
« Last Edit: October 04, 2022, 12:47:47 PM by AE0Q »
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NSGA Edzell 1974-77  CTM2  GM5BKC : NSGA Rota 1972-74   ZB2WZ, SV0WY
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K6AER

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Re: Proper way to use mix 31 rings x2
« Reply #3 on: October 04, 2022, 05:22:44 PM »

I doubt seriously RF is causing your problem via the AC feed.

You will get much better RF attenuation on the AC feed by placing a couple of .1 Mfd 200 volts caps to chassis ground..
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AE0Q

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    • AE0Q Amateur Radio
Re: Proper way to use mix 31 rings x2
« Reply #4 on: October 04, 2022, 09:36:02 PM »

I installed one 3.0" ID mix 31 ring on the AC line close to my internet router.

How does the router connect to the internet?  I have a DSL modem and have had to put ferrites on the line to the telephone jack that has the DSL signal.
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NSGA Edzell 1974-77  CTM2  GM5BKC : NSGA Rota 1972-74   ZB2WZ, SV0WY
https://radioandtravels.blogspot.com/
http://www.qsl.net/ae0q/

KH6AQ

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Re: Proper way to use mix 31 rings x2
« Reply #5 on: October 06, 2022, 08:07:36 PM »

You can try both methods, cores separated and cores stacked. Cores stacked approximately double the CM impedance. Separate cores -- CM filters in series -- also double the CM impedance. Don't worry about windings overlapping. Try with and without. RFI fixes are often all about experimentation. On my router I have one FT240-43 cores on the DC power and on the Ethernet cables with about a dozen turns. It fixed the issue of transmitting knocking the router off. 

I would not apply any fixes, such as capacitors, directly to the AC line. That will not provide CM impedance and it must be done with Y-type safety rated capacitors. A large cap such as 0.1 uF will draw enough line-to-GND current to trip an GFI circuit breaker.

On the router ferrites on the AC power and on the Ethernet cable(s) can be a solution.
« Last Edit: October 06, 2022, 08:11:29 PM by KH6AQ »
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WA3SKN

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Re: Proper way to use mix 31 rings x2
« Reply #6 on: October 08, 2022, 03:20:31 PM »

DSL uses 25kHz---1.1MHz square waves and requires filters to meet FCC part 15 specs.  Lots of RFI potential!

-Mike.
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KD6VXI

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Re: Proper way to use mix 31 rings x2
« Reply #7 on: October 26, 2022, 12:58:55 PM »

I installed one 3.0" ID mix 31 ring on the AC line close to my internet router. It seemed help, but it's not quite there yet. I can't add any more turns because they would overlap one another, so I thought maybe adding another 3.0" ring would solve this RFI issue.

Question: Do I butt up both rings together and wrap my turns through both of them OR do I seperate the rings having several turns on each ring with a small length of AC line between them?


Thanks :)

Instead of putting the 2nd ferrite on the AC line, how about putting it on the digital input (DSL / Cable / Ethernet from roof mounted antenna) to the router....?

--Shane
WP2ASS / ex KD6VXI
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