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Ferrite Bead Advice For AM BC Interference Supression

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CK-722
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Ferrite Bead Advice For AM BC Interference Supression

Post by CK-722 » Wed Dec 26, 2018 8:42 pm

Ferrite beads. What kinds should I get and where's the best place to put then on cords? What devices?

Which devices? Concerned about remote control smart phone on off dimmers for LED lights.

1) Transformers/power supplies
2) Routers
3) Remote control hubs
4) Others?


Is THAT where they got the idea for the 486-SX?

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Turkeytop
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Re: Ferrite Bead Advice For AM BC Interference Supression

Post by Turkeytop » Wed Dec 26, 2018 9:00 pm

I have no idea what this is about, but it looks intriguing. I'll be following this thread.



CK-722
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Re: Ferrite Bead Advice For AM BC Interference Supression

Post by CK-722 » Wed Dec 26, 2018 10:20 pm

They are like transformer cores that fit onto the outside of wires leading to and from noise producing electronic devices. The ferrite is supposed to trap the electromagnetic interference and limit its range by concentrating the electromagnetic field near the device in the ferrite material.

This should help on 160 meters, MW domestic, and shortwave also.

The advice I seek is 1) are they effective?, and 2) placement for best results. I guess I could experiment, but I am getting so frustrated by the interference explosion from endless new devices. Don't tell me 250 watt FM translators are the answer for more than a few locations. I'm listening to AM in the car now because of the complete block out of FM signals except the limited formats of full power stations, and no out of market stations. I feel like I am in Cuba, and the government run stations blot out all the Florida stations.

I've even sought solace and comfort with Alexa. But deep down, she's not the brightest bulb in the string, but you know what happens to the brightest bulb in the string anyway? It burns out like a 2.5 V Christmas bulb in a 3.5 V series string.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

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Turkeytop
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Re: Ferrite Bead Advice For AM BC Interference Supression

Post by Turkeytop » Thu Dec 27, 2018 12:53 am

When a resident at our mobile home park in Florida commented that he was feeling a lot better, I thoughtlessly reminded him that a light bulb gets brighter just before it burns out. Two weeks later, he was dead.

Like I said, I'll be following this thread. I'm plagued with RFI, most of it originating from within my home. If there's a cure, I want to know about it.



CK-722
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Re: Ferrite Bead Advice For AM BC Interference Supression

Post by CK-722 » Thu Dec 27, 2018 1:23 am

Well, you could turn off the main breaker to see if the problem is in your house. But then you have to reset everything. The microwave even requires the date to be put in, not just the time. Most people have never had to exhaustively determine what every breaker controls. But you can eliminate a few from consideration, and turn the rest on and off to test. One time it was a portable room humidifier. But if you have neighbors, it might be in their domicile. They get as honked off as Julia Louis Dreyfus if you turn their electricity off like in Christmas Vacation. Just tell them you were confused and thought it was your breaker. One neighbor had a heat exchanger with dirty motor brushes. It wiped out weak High VHF channels, even in the analog days. He was a good neighbor and fixed it.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

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CK-722
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Re: Ferrite Bead Advice For AM BC Interference Supression

Post by CK-722 » Thu Dec 27, 2018 1:48 am

I had an acquaintance who lived in Warren. He had an analog TV and no converter. For a few years after the final US flash cut, he just watched CBET Channel 9. When they went digital, he had no TV at all. Six months later, he was dead. When Digital Kills, it's as deadly as wild animal attacks. I did offer numerous times to go down there and hook up a converter, but he declined. I think he thought his house was too messy for company.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

RTN Price. Not guaranteed. As of 12:30, 157.71 Down 0.22.

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MWmetalhead
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Re: Ferrite Bead Advice For AM BC Interference Supression

Post by MWmetalhead » Thu Dec 27, 2018 7:07 am

Wow. Channel 9's signal in Warren - at least the NW part where I once lived - stunk when using rabbit ears. It was watchable but snowy & sparkly.

Analog channel 9 also reduced its power a year or two before CBET went 100% digital for reasons unbeknownst to me.

Even when CBET was running full power from McGregor, I generally received stronger analog reception from Flint's WFUM-TV than I did from CBET.


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SolarMax
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Re: Ferrite Bead Advice For AM BC Interference Supression

Post by SolarMax » Thu Dec 27, 2018 10:52 am

CK-722 wrote:
Wed Dec 26, 2018 8:42 pm
Ferrite beads. What kinds should I get and where's the best place to put then on cords? What devices?

Which devices? Concerned about remote control smart phone on off dimmers for LED lights.

1) Transformers/power supplies
2) Routers
3) Remote control hubs
4) Others?
1) Transformers and most transformer power supplies ("linear") don't as a rule emit significant EMI/RFI. Badly designed and made switching supplies and "wall warts" (most, nowadays) wreak havoc.
2) Routers - Wireless router RF is emitted at 2.4 or 5 GHz, not an issue for BC AM. Problems arise with their power supplies, and with any ethernet cables connected to them. Shielded ethernet cables rather than ferrites are more effective for suppression of any RF.
3) Remote control hubs - same issues, as well as for home alarm system hubs, especially those with wiring to their sensor points.
Light dimmers and electronic (non-mechanical) timers can be either OK or (usually) awful. Not much user EMI control other than finding brands that are cleaner than others. Never have "touch" activated lamps in the house.
Particularly bad these days are new furnace controllers, washer or dryer controls etc. And, your neighbors' "grow lights" hidden in a basement or attic.
Make sure house wiring is to code. A big problem is often poor connections within wiring boxes and especially interrupted or loose neutrals. Proper ground and bonding is also important.
Externally generated noise, usually the problem, is, for the most part, out of your control. For AM reception a directional antenna like a loop can at least null out some noise.
Another use of ferrites (beads and cores) is to prevent ingress of local RF. Hams use them to keep any stray RF from their transmitters from getting into USB cables used for audio and control between radios and computers, and on transmit antenna feed points as a "choke balun" to keep RF from radiating off coax feed line shield. This is also combined with good RF grounding practices.
There are many kinds of "mixes" that are used to manufacture ferrites. Different mixes are used to provide their most effective suppression for different frequency ranges. Bargain ferrites may or may nor be worth the price as you won't know which mix was used to make them and what frequencies they're designed to be used at.
Best location is nearest the source of the noise, or, wherever else helps the situation.
Keep in mind also that many sources of noise start at a fundamental frequency, usually 60 or 120Hz, with nasty, harmonic-rich waveforms, square wave or pulsed, that can go up well into VHF range. So a filter that works at low frequency ranges may not effectively suppress the higher frequency harmonics.

Here are some informative links about EMI suppression and use of ferrites:

http://www.k0bg.com/beads.html
http://www.elmac.co.uk/ferrite.pdf
http://www.elmac.co.uk/Trouble_with_wallwarts.pdf
http://audiosystemsgroup.com/RFI-Ham.pdf
http://audiosystemsgroup.com/PowerFilters.pdf

Some good sources:
http://www.amidoncorp.com/ferrite-toroids/
http://www.kf7p.com/KF7P/Ferrite_chokes.html
http://www.kitsandparts.com/toroids.php



CK-722
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Re: Ferrite Bead Advice For AM BC Interference Supression

Post by CK-722 » Thu Dec 27, 2018 2:45 pm

Thanks a lot for those links and information. I'll try to see what information I can get as to which devices are causing the most trouble and start there.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

RTN Price. Not guaranteed. As of 12:30, 157.71 Down 0.22.

Artificial Intelligence is a Child that needs a Parent to guide it through.

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ZenithCKLW
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Re: Ferrite Bead Advice For AM BC Interference Supression

Post by ZenithCKLW » Thu Dec 27, 2018 4:19 pm

I found a battery charger for a cordless drill wiped out the entire AM band in my house and yard. Unplugged that thing and my radios can hear again.



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Ed Joseph
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Re: Ferrite Bead Advice For AM BC Interference Supression

Post by Ed Joseph » Mon Jan 07, 2019 5:22 pm

One thing to consider... SMART meters from utilities. They have transmitters in them, and from what I've experienced, no regard whatsoever for Part 15 radiation specs. I've been considering replacing as many switching PSU's as I can with linear ones. CFL and LED bulbs are pretty noisy as well.


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