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Effect of magnets near a transceiver


IronArcher
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So I had an idea to bundle everything for my base rig into one all in one box. I’ve seen others do this with ammo cans and other such enclosures.

My question is, how would the magnets of say a larger speaker affect the transceiver?

Something to worry about?

Insignificant?

 

Thanks.

 

P.S. I always like much better than average audio (usually plug my mobiles into the stereo system, not some little external speaker)

I have a 2x10 guitar cabinet that would fit everything, but if the speakers are going to mess with stuff, I have a sound bar that might work.

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I expect no affect. Why?

 

Reason 1. It is act of a changing a magnetic field that induces currents to flow in another conductor. In the case of a speaker, the permanent magnet is on the outside. The speaker coil in which currents flow is substantially confined to the interior of this otherwise large constant-magnetic-field structure.

 

Reason 2. The frequencies at which the speaker operates are audio frequencies. The only audio frequencies used in your radio are those used to supply audio to the radio to transmit, and from the radio to a speaker for listening. When you are listening you want the speaker to reproduce the receive audio. Good there. When transmitting, the speaker is not being used. Good there. And remember of course that almost every radio has a speaker in it right next to the electronics.

 

Hope that helps.

 

Michael

WRHS965

KE8PLM

 

So I had an idea to bundle everything for my base rig into one all in one box. I’ve seen others do this with ammo cans and other such enclosures.

My question is, how would the magnets of say a larger speaker affect the transceiver?

Something to worry about?

Insignificant?

 

Thanks.

 

P.S. I always like much better than average audio (usually plug my mobiles into the stereo system, not some little external speaker)

I have a 2x10 guitar cabinet that would fit everything, but if the speakers are going to mess with stuff, I have a sound bar that might work.

 

Sent from my iPad using Tapatalk

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Well, considering circular isolators use magnets, magnets have some affect over RF fields... so it was good to get more points of views.

 

G.

I don’t want to derail this thread, but at least it is related. G, perhaps if you have some test equipment around that you could mock up a couple of tests for us. If interested, perhaps we could start a new thread. One test could be the effect on transmitter output signal integrity and another on the receiver performance before and after placement of a large static magnet field (large rare earth) directly on the exterior of a UHF radio chassis. Similar tests could also be conducted covering the effect on transmission line performance in the presence of same. I don’t have ready access to the caliber of equipment needed for this so I cannot mock it up and measure it. Admitted that is probably a better topic for those in the amateur community rather than in GMRS. Just a thought.

 

Michael

WRHS965

KE8PLM

 

 

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Yeah, its probably a better question for hams, certainly for more experienced operators with more mathematical knowledge than I do... 

 

I have some test equipment to measure a few things, but I think those kind of measurement are way above my equipment capabilities.

 

G.

 

 

I don’t want to derail this thread, but at least it is related. G, perhaps if you have some test equipment around that you could mock up a couple of tests for us. If interested, perhaps we could start a new thread. One test could be the effect on transmitter output signal integrity and another on the receiver performance before and after placement of a large static magnet field (large rare earth) directly on the exterior of a UHF radio chassis. Similar tests could also be conducted covering the effect on transmission line performance in the presence of same. I don’t have ready access to the caliber of equipment needed for this so I cannot mock it up and measure it. Admitted that is probably a better topic for those in the amateur community rather than in GMRS. Just a thought.

Michael
WRHS965
KE8PLM


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I would not quickly discount the interaction of any large magnet and a radio transceiver. Recently I read in a trade magazine of a company that makes Class D audio amplifiers for Public Address systems. These amplifier have ferrite chokes inside to decouple the high frequency components of the amplifier. Some of their customers were screwing these amplifiers  to overhead speaker boxes in close proximity of the speaker magnet. They encountered all sorts of problems. These are common rare earth permanent magnets used for all sorts of things. In a speaker, they create a strong fixed field whether powered or not.

 

Ferrite chokes are used throughout modern radio transceivers and many are quite small. Others like used in the power amplifier are large but already operating under heavy current flow. Current flow can saturate the magnetic properties of the choke, or any iron transformer.

 

AC and DC current in a ferrite choke or transformer, creates a magnetic force. Whether it be electrically or magnetically coupled, the ferrite choke can become saturated to the point where it no longer becomes capable of absorbing or transforming electromagnetic energy. It wont be damaged if you remove the external magnet, but it can cause a malfunction and possibly a fault.

 

I would not place any powerful magnet on top of an electronic device.

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I would not quickly discount the interaction of any large magnet and a radio transceiver. Recently I read in a trade magazine of a company that makes Class D audio amplifiers for Public Address systems. These amplifier have ferrite chokes inside to decouple the high frequency components of the amplifier. Some of their customers were screwing these amplifiers to overhead speaker boxes in close proximity of the speaker magnet. They encountered all sorts of problems. These are common rare earth permanent magnets used for all sorts of things. In a speaker, they create a strong fixed field whether powered or not.

 

Ferrite chokes are used throughout modern radio transceivers and many are quite small. Others like used in the power amplifier are large but already operating under heavy current flow. Current flow can saturate the magnetic properties of the choke, or any iron transformer.

 

AC and DC current in a ferrite choke or transformer, creates a magnetic force. Whether it be electrically or magnetically coupled, the ferrite choke can become saturated to the point where it no longer becomes capable of absorbing or transforming electromagnetic energy. It wont be damaged if you remove the external magnet, but it can cause a malfunction and possibly a fault.

 

I would not place any powerful magnet on top of an electronic device.

That is an excellent point regarding potential saturation of some components. It is a certainty that there will be some specific conditions where the presence of a static magnetic field in the presence of some equipment and components will have negative consequences and many where it will not. It comes down to the circuit, the components used, intensity of the field and degree of shielding among other factors.

 

Sounds like a great research project for one of our readers aspiring to get their PhD. :)

 

Best regards,

 

Michael

WRHS965

KE8PLM

 

 

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So I thought I would share the results from a quick experiment I performed today. Nothing with the transceiver, but instead with feed-line (coax type).

 

My test objective was to see if the introduction of a static magnetic field would cause the displayed results from live VNA S11 measurements to change.

 

I began by calibrating my NanoVNA H4. Then I connected a 12’ length of RG-58 to the VNA, and terminated with other end of cable with a 50 ohm dummy load. With simultaneously stable readings appearing on the VNA (Smith chart, SWR, MagLog) I tried all of the following:

 

1) Placed neodymium magnets next to the coax, approaching slowing and then rapidly.

2) Removed the magnets from the coax slowly and rapidly.

3) Placed magnets on both sides of the cable and then moved them up and down the cable at various speeds. First slowly, then as rapidly as I could.

 

I performed the experiments using the frequency range of 450-480 MHz. Then again with the range of 50-900 MHz.

 

During the tests, I observed no visual change in the results displayed on the VNA under the conditions described. No blips, bumps, contouring at all. This suggests to me that non of my actions had any notable affect on the frequencies under test.

 

Take it for what it is worth. Merely an experiment performed for which I thought I would share the results. Simple and fun.

 

Do need read anything into this test with regards to the transceiver.

 

Regards all.

 

Michael

WRHS965

KE8PLM

 

 

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