Microwaves and Magnets

[Airabel]

Can someone resolve a microwave issue for us?
We have a Sport and have run out of room on the metal marker board for any more National Park magnets to fit on it. The only other metal surface to add magnets are the sides of the microwave. Does anyone know if magnets will harm or affect the microwave's performance?

[KelloggKid]

As long as you don't put them inside the microwave they should have no effect.

[rmkrum]

They might vibrate a bit when you are towing...and possibly scuff the paint.

[Boxite]

The "heart" of every microwave.... is a HUGE, POWERFUL MAGNET... It's shaped like a doughnut and aligns the RF-energy through a wave-guide to direct all that RF energy towards your food to heat it up.
There is no harm in placing refrigerator-type magnets on a microwave.

[Lily&Me]

As an alternative, you might mount a magnetic board somewhere, and put your magnets there.

I have one on my bathroom door.

Maggie

[Mollysdad]

No danger. I have magnets on my vintage Amana Radar Range at home.

[rmkrum]

As a side note on the Microwave technology:

The huge magnet is part of a vacuum tube properly called a "Magnetron" and it works by spinning a cloud of electrons inside the tube past a bunch of cleverly shaped slots that generates the radio frequency it puts out to cook the food. The magnet is what makes the electrons spin.

In the RF engineering trade, a Magnetron tube is often referred to as a "Maggie". Fancy that...

(Traveling Wave Tubes (TWT), another sort of microwave amplifier, are often referred to as "tweets"..just another version of verbal shorthand in the engineering field...that is more-or-less G-rated)

--This has been your random engineering factoid of the day, stay tuned for more weirdness...

[waninae39]

if you want to destroy the magnetron tube in your uwave, place small bits of metal in it
it you want to create a fire and possibly injure people, place a magnet or a large piece of metal in and turn it on

the screen pattern on the front has holes that are too small for the uwave waves to go through. though the inside is metal, it was DESIGN and tested to be safe. adding more metal is just dangerous

[rmkrum]

Interestingly, there was a brand of microwavable meals that had an aluminum crimped-on lid with a plastic container. They did not require refrigerated storage, IIRC.

The dimensions of the crimped-on rim that remained once the lid was removed were carefully calculated and tested to NOT be a hazard to the oven's tube. Clever engineering let it warm properly without reflecting energy back into the Maggie, and destroying it...wonder how many tubes they blew out testing that idea?

Clever package design, but bland, lousy-tasting food...have not seen them on the market in a long time--think it was soup or something like that...

[Boxite]

The idea/invention of the microwave oven anecdotally came about as a radar-technician worked on a radar magnetron and noticed the chocolate bar in his shirt pocket melted.... hence, the brand-name "Radar-Range".

Aircraft mfr'd within the last 20 years have their weather radar units automatically switched to "non-transmit" mode when a switch on the landing gear detects the aircraft has landed. This is intended to belay hazards to workers on the airport and to prevent sparks in those nice, large, fuel trucks and other vehicles/airplanes on the ramp. (Prior to that recent improvement we had to remember to switch it off after landing so as to not fry the eyeballs and other organs of those who walked up to the plane to place chocks on the nose-gear-wheels.)

[rmkrum]

Navy E-3 "Hawkeye" radar technicians know how to jumper the "squat switch" circuit if the aircraft is on the ground in hostile territory.

If one engine is running, the radar can be fired up and will kill anything within range of the beam. The cockpit and other windows in the aircraft are carefully shielded to keep the RF out of the cabin.

Not stuff you want to be around at very high power levels...they get well clear of the runway/aircraft carrier before firing that big 'Frisbee' antenna and transmitter up...

[Msherw]

...and the microwave oven makes a dandy place to store (with it off or unplugged) your sensitive radios and other items should an EMP or Carrington event CME strike. LOL. After an EMP not much is going to work except non electronic items so it is likely an exercise in futility. Our tow vehicles will probably be rendered doa.

Just some interesting trivia. As you were...

[Boxite]

Originally Posted by Msherw

...and the microwave oven makes a dandy place to store (with it off or unplugged) your sensitive radios and other items should an EMP or Carrington event CME strike. LOL. After an EMP not much is going to work except non electronic items so it is likely an exercise in futility. Our tow vehicles will probably be rendered doa.

Just some interesting trivia. As you were...

Really? What about the Faraday-Cage surrounding the electronics (which most folks refer to as the "body" of the vehicle.)

Yet another advantage of an Airstream over SOBs when the Sheet hits the Fans.)

[Al and Missy]

The glass in a microwave oven has perforated metal screens to prevent the escape (or ingress) of electromagnetic energy. Trailer and vehicle windows do not.

That said, if you are in the area of an EMP event, you likely have bigger problems than the survival of your electronics.

Al

[Paprika]

"Interestingly, there was a brand of microwavable meals that had an aluminum crimped-on lid with a plastic container."

The use of what are called "susceptors"--basically cardboard with a super-thin film of aluminum--is very common in packaging frozen prepared foods such as pizzas. They generate heat to help with browning/crisping, helping to mitigate the sogginess often seen when microwave-heating frozen snacks. Because the susceptor's metal film is extremely thin (semi-transparent in the ones I've seen), not enough energy is reflected back to the magnetron to cause damage.

[rmkrum]

Yup. RF design at microwave frequencies is “interesting” in the Spockian sense. Been involved in a few that seemed to bend the known laws of physics at times.

[Msherw]

Originally Posted by Boxite

Really? What about the Faraday-Cage surrounding the electronics (which most folks refer to as the "body" of the vehicle.)

Yet another advantage of an Airstream over SOBs when the Sheet hits the Fans.)

Interesting observation this weekend while camping in a very weak cell RF area: cellphones would not work in the AS but would work barely in the trailer of our friends. I literally had to take my phone outside and lay it on the wood picnic table to get a usable signal. If I moved it anywhere near on any side of the AS it would register No Service.

I realize a greater RF signal works fine in the AS. But in a marginal area, the AS will block weaker cell signals.

[Mollysdad]

Originally Posted by Boxite

... hence, the brand-name "Radar-Range".

I still have, and use daily the original Amana Radar Range. Vintage 1981?
Every button on the touch pad works, it's big and there's no turntable. I think the antenna rotates. The only problem is the lightbulb doesn't last long inside.
I have no intention of getting a new one.

[PKI]

Our Amana died, but it did get a lot of use, before it's unplanned end.

The best microwave story I've heard was the one about the big German guy who spun the frozen tuna in front of a microwave horn to see if the tech would work for a commercial defrosting application. As one might expect, don't try that at home. Pat

[rmkrum]

Originally Posted by Mollysdad

I still have, and use daily the original Amana Radar Range. Vintage 1981?
Every button on the touch pad works, it's big and there's no turntable. I think the antenna rotates. The only problem is the lightbulb doesn't last long inside.
I have no intention of getting a new one.

Many of the older microwave ovens had a stirrer fan with blades bent at varying angles to try to evenly distribute the microwave energy. As the fan rotated, the microwave beam was scattered around the cavity as it bounced off the fan blades.