A lot of microwave oven have a minimum amount of fluid to be heated because it absorbs the energy and doesn’t let it fly around loosely to get back to the magneton.
I had one oven fry the terminals on the Magneton because some one kept heating a small cup of coffee, which was below the quantity threshold of fluid.
The older ones stated the quantity on the back while some of the newer once use a focus aperture method to stop this feed back.
The value of energy in the form of MW is rated in volts, and this energy concentrated on a small spot can jump the insulation and cause damage.
A lot of shellac on magnetons has been fried from this energy making the electro magnetic portion of the coils just a lump of copper with out separate insulated windings.
Today they use a focused beam or aperture much like a one way valve with the lens or aperture restricting the energy back into the cavity.
Unfortunately I don’t know which brands are better than others, while some ovens are completely immune from this phenomenon.
I guess mine must be ok and my previous oven (20 years or more old)
was ok too because i often boil small quantities of water in a small
styrofoam cup in there. I did notice burning of the material that is
used to cover the port hole, but apparently that was caused by
food hitting it during cooking over the years. I keep my new one
(the port) covered with clear plastic food wrap and that seems to
prevent this from occurring.
I did notice one response however, which i find very interesting but
as yet can not explain...that is, when i cook something that boils or
rather foams up (like spagetti or even Egg Beaters) the microwave
emits a low frequency sound like a hum, but as the material begins
to foam up the intensity of that hum increases, becoming somewhat
louder as the foam starts to form. I thought this might be a way of
detecting when the food starts to overcook or boil over.
I dont think it occurs with water though, unless there is something
in the water like spagetti, and i think soup does it too.
Of all the cool displays available in the microwave, the best is still a match or candle flame. You can leave it exposed, or cover it with a clear drinking glass, elevated so it gets air. Ball lightning! Sort of.
Of course, this 'spearmint may damage your oven!
Our first was an Amana Radarange (over $500) back in 1978. The capacitive seal on the front door seemed to be the biggest problem and I had to replace it when things started arcing over.
I haven't looked up µwave history to see who was first out there. Amana (curious for a small Iowa religious sect) was one of the first in the consumer end. I'd guess that Litton might have been one of the biggest for commercial units used in restaurants and on commercial airlines and figure that they may have been the most robust. they made most of the maggies back then and may have wanted to capitalize on their own "retail" products as well.
Dean
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).
Remove the turntable if it has one and invert a bowl over the turntable hub with a dinner plate on top of the bowl. Get some thermal paper, like old fax machine paper or blank thermal labels and wet them. Arrange them on the plate and fire up the oven. You will see the MW radiation pattern by the changing of the thermal paper color due to the heating of the water!
Got an ultrasonic cleaner?
If it is reasonably powerful put a strip of aluminum foil in the solution for a few seconds. Hold it up to the light. It will be full of pinholes. Useful for looking for 'dead spots' in the tank.
I have never had a problem with either of these but as they say...Use at your own risk!
Thats cool, as soon as the Sears guy fixes my new u-wave (so much for the outlet store) with the arcing magnitron, my old oven will get to try a few of these and other experiments I have heard of before it hits the dumpster. I think the old one is a 750W, should do some harm.
Dean, I think it was Raytheon that invented the oven who then spun off the Amana company to sell to consumers. Back in the day (more like late 80s) when I worked for Raytheon, I heard stories of birds falling cooked from the air in front of radar sets. I also saw large warnings of where not to stand printed on the front covers of the operators manuals. Not sure when Litton came in the scene, they may have been a subcontractor for Raytheon at the beginning of the trend.
I remember in the late 70s when these ovens were catching on, sales guys would have a platter with neon bulbs glued (or built into it I don't remember) all over it, they would put it in the oven to show how evenly the microwave energy was dispersed with their new technology bla bla.
A microwave oven will also light a small fluorescent tube, but it will get quite hot so shorten the 'test' Also a paper clip bent in a circle placed on a glass plate with the ends about 1/4" apart will arc!. Look up nucleation for some rare but potentially hazardous results of boiling water in a microwave!
Microwaves are interesting devices. The one I got my parents about seven years ago even suggests covering certain portions of defrosting food, such as the outer edges of chicken and roasts, with Al foil. From the first manuals I read about MW ovens it said NEVER put anything metal inside them. But this oven came with a metal shelf! (Never used it, though.)
One OOPS! was a Thanksgiving OOPS! I was lucky enough to be the victim of. It taught everyone else in the family what NOT to do so I guess in a way I'm lucky it happened to me. Thanksgiving and Easter are two days my mom likes to make very fancy and bring out the "good" dishes. Not real expensive or cherished items but "special occasion" type dishes. These special dishes have silver (as in the metal Ag) trim along the rim of the plates, bowls, etc. as well as the wheat flower pattern painted on them. (If you see what's coming it is okay to laugh as we all did after the fact.) Well saving your plate to have fourths after dinner means less plates to wash. It also means when you heat turkey, stuffing, mashed potatoes, gravy, and all sorts of things in the MW you are also putting metal (the before mentioned Ag) in as well. The first second or two was okay. Then a ring of fire the diameter of the plate fills the inside of the MW. Thus everyone now knows not to put these plates in the MM.
On one MW I was heating something, defrosting ground beef I believe, when I saw a flame and sparks shoot out of the food. I stopped the MW and checked to see what had happened as I'd not seen this happen with regular food before. Buried in the food was a twist tie. Likely if the food was not put in the MW it would have been missed.
As far as experiments. A coffee cup filled with water will provide a load to prevent feedback. Supposedly newer MW can run fine without anything inside them. Even if true the cost of a cup of water is well worth the piece of mind. Though my latest home MW was free I like it too much to risk damaging it. (It has the same interior room as my previous MW, is 50% more powerful, and is much smaller on the outside.)
CDs are always fun. Candles are neat as well but I was afraid of accidentally burning something inside the oven. Have not done that for some time. As far as the plasma bulbs....Isn't this just the filament and the conductors burning up from the RF inside the glass bulb? Also, if you get G4 on cable, check out a show called Brainiac. I've not seen it for a few weeks now but they perform all sorts of experiments on different things, including MW, so you don't have to. Also check out Mythbusters on Discovery Channel. (This assumes US TV channels.)
No trees were harmed in the creation of this message. But billions of electrons, photons, and electromagnetic waves were terribly inconvenienced!
yes the metal in the bulbs start the arc. but the thicker bulbs don;t burn the filiments out..(1,500 watt incadescent mogul base )
but a household bulb will vaporise...may pop also if it heats up too quickly..i found this out the hard way..
another dish thats not good inthe microwave is melmack same material thats used on many pot and pans. they absorb the heat big time..and we all know what that stuff smells like when it burns..PEEEYUUU !
This old man seems to recall that the first consumer microwave (heating) device was called the "Hot Dogger". It had slots for hotdogs, and was like the old "Close and Play" record player (Told you I am old!). All it did was cook hot dogs in a super short amount of time. Microwave ovens hit the shelves soon afterwards. I'll just bet the hotdogger had more or less slots than the standard pkg of hotdogs contains too! Dave
