Thread Number: 35222
Potential Problem With Older Microwaves
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Post# 526633   6/24/2011 at 10:55 (2,496 days old) by sudsmaster (East of SF, West of Eden, California)        

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We've seen a number of posts here from people who enjoy and search after older microwaves.

While I don't deny that the build quality and design of older microwaves may be more appealing, it's my understanding that microwaves have a certain useful lifetime. After a number of years the magnetron that delivers the energy to the food weakens, and eventually fails. In many cases it's cheaper just to go out and get a new microwave than try to get the old one fixed.

I see this problem all the time in the workplace, where the company has provided microwaves in the lunch room for employees to use. In some cases these units are pretty long in the tooth and often they can take two or more times as long to heat a meal than a newer version.

So I'm wondering... is there something special about an early Amana or Radarrange or Litton microwave that enables them to deliver full power forever? Or are people collecting these because they like the way they look, not necessarily for their ability to heat anything in a timely manner?

Post# 526641 , Reply# 1   6/24/2011 at 11:55 (2,496 days old) by retropia (Central Ohio)        

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For me it's just nostalgia. I may use my Radarange to warm coffee in my office, but in the kitchen, our newer over-the-range microwave is more practical as a daily driver. I suppose I could run a test boiling water in a mug in both, to see which is faster. It doesn't really matter to me, though.

There were three Radaranges I used in the mid to late 1970s that hold fond memories for me.

Post# 526642 , Reply# 2   6/24/2011 at 12:04 (2,496 days old) by rp2813 (The Big Blue Bubble)        

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My 1980 Panasonic seemed to do fine up until we left it behind at our other house three years ago.  It was only 750 watts compared to 1,300 watts on the Panasonic we have now, so it for sure did everything slower, regardless of the condition of its magnetron.


Post# 526644 , Reply# 3   6/24/2011 at 12:06 (2,496 days old) by PhilR (Quebec Canada)        

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I have two older microwaves (a small Hitachi from 1982 and a Frigidaire-badged Amana from 1978) and I use them quite often. I don't have newer stuff and I mostly use them to reheat, which they do quickly. I often set the power level lower on the Frigidaire. A friend of mine has an expensive, 4 years old over-the-range Panasonic microwave oven and last year, his girlfriend heard an explosion while she was using it and it was dead... They had to have the magnetron replaced at about 10 times the cost of my two current microwaves!

I never cared for anything newer! I mostly like stuff from the fifties to the seventies and other than my cell phone, my computer, digital camera, a GPS, toothbrushes, a tv, two vehicles from the early nineties (my newest vehicle is 18 years old while my oldest one is 46), I have very few modern things! Last year, after replacing the motor in my 1990 Toyota pickup, I had the motor replaced in my 1990 electric shaver, the person who replaced it commented that it was probably not worth replacing as the shaver was old, I said it wasn't, I got it new just 21 years ago!, I replaced the batteries just 3 times and the blades once! I'm not the kind of person who likes to replace it's old stuff by newer one if it's still good!

I live with rotary phones, the watch I'm currently wearing is from 1971 and I have no appliance newer than my 1978 and 1982 microwave ovens!

Post# 526659 , Reply# 4   6/24/2011 at 12:44 (2,496 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
As With Everything It All Depends

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Upon how "used' the old microwave was during it's previous lifetime.

Given the results many homes didn't use microwaves for more than reheating foods, boiling water, etc. So there could potentially be lots of life left in said oven.

As one who is hunting for a vintage microwave read something on the Interent this week. It came from a repair/tech service that stated all new microwaves loose about 30% of their power within the frist few months of use, then things slowly decline from there.

Consider also like many appliances back then microwave ovens were, for the better brands at least way over built for their purposes. One routinely finds MCs out there >15 years old that apparently are still working fine, the usual reason they are being chucked is due to death of previous owner or a kitchen remodel. Of course the other reason is the desire to have something new.

Aside from the turn table, inverter systems, humidity sensors and perhaps a few things I cannot remember there isn't that much "new" to microwaves. Some old er features such as no turn table at all are making a come back (Panasonic).

Post# 526663 , Reply# 5   6/24/2011 at 13:04 (2,496 days old) by PhilR (Quebec Canada)        

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My 1982 Hitachi microwave does have a humidity (or heat?) sensor.

It's great for reheating. Just press one button and it starts and stops automatically.

Post# 526666 , Reply# 6   6/24/2011 at 13:16 (2,496 days old) by cfz2882 (Belle Fourche,SD)        
usefull life of microwave ovens...

....may well be many decades-my old oct.1984 built hotpoint(GE) microwave still
working like it did when it was bought at K-mart in 1985,this one is my DD
All my other oldies,including '68 radarrange,'70 westy branded RR,all still
going strong.Mechanical parts;fan and stirrer motors,timers, etc seen to give
more trouble than the simple electronics of the magnetron system.

Post# 526675 , Reply# 7   6/24/2011 at 14:33 (2,496 days old) by sudsmaster (East of SF, West of Eden, California)        

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Well, granted, the old microwaves at a former employer got a lot of heavy use for years in the company lunchroom. They cooked so weakly that it couldn't be from just a lower designed in wattage rating.

I once had a small Amana badged 800 watt Hitachi microwave. It had no turntable but worked fine. But after about 10 years it suddenly stopped working. I tried replacing the fuse a couple of times but it would blow as soon as the thing was turned on. I replaced it with a Kenmore that is still going strong (along with a Panasonic I got as well). The Kenmore is actually a better designed appliance, IMHO. Its sensor system seems more accurate than the Panasonic, at least for popcorn and beverages. However the Panasonic does have the inverter technology that is nice for re-warming foods (typically I will set a couple of slices of pizza on the inverter defrost setting for about .4 lbs, and it rewarms them perfectly with no overheating).

Perhaps it would be wise, however, to test how long a vintage microwave takes to heat a cup of water before purchase. No sense in paying top dollar for an antique that may need a new magnetron.

Post# 526678 , Reply# 8   6/24/2011 at 14:48 (2,496 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
What Always Gets Me Is

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How many persons want nearly a hundred or in some cases several for a "vintage" microwave. I suppose something like a NIB Amana Radarange from a certain period *might* be worth that amount, but not your average daily used machine with the interior coated in cooked on gunk.

As for heating methinks it is not always about watts (heating power), how well the oven was designed to distribute microwaves must come into play as well.

Don't know if this is true but many report their vintage microwaves especially Radaranges heat more evenly and sometimes faster than today's higher watt versions.

Post# 526682 , Reply# 9   6/24/2011 at 14:58 (2,496 days old) by whirlcool (Just North Of Houston, Texas)        

Our old Litton (that is currently sitting unused in the garage) seemed to cook slower and slower over time. When the power surge we had two years ago took out our appliances we used the Litton for a short time again. It has a power rating of 750W.
The Kenmore microwave we had at the time that got blown out by the surge was 1000W.
The Litton took a lot longer to defrost and cook things than the Kenmore did. I thought it was just the difference in power, but it may have been age too. We bought the Litton in 1976 and was in continuous use until 2001.

Post# 526705 , Reply# 10   6/24/2011 at 17:32 (2,496 days old) by statenislandgwm (Staten Island NY)        

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I have a Radarange that was manufactured in April of 1986. I live in an apartment so it is my daily driver, to me it seems faster than any other microwave I have used. The only problem with it is that I have a friend who won't go by it when it's on, I think the hum of the magnetron is what scares him. LOL!

Post# 526718 , Reply# 11   6/24/2011 at 18:19 (2,496 days old) by cfz2882 (Belle Fourche,SD)        
blown fuse

IIRC,some microwave ovens have the door interlock switches arranged to switch as
a short circuit and blow the oven's fuse if there is a foreign object in the
latch or other malfunction with the door...thankfully washers don't have that
safety feature LOL

Post# 526720 , Reply# 12   6/24/2011 at 18:25 (2,496 days old) by sudsmaster (East of SF, West of Eden, California)        

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"The typical life of a magnetron tube is approximately 2000 hours of operation."

Let's see... if you use a microwave oven for, say 10 minutes a day, and don't abuse it (run it empty, or with metal in it that causes arcing, or have bad line voltage) that means the magnetron may last 33 years. I would say that 10 minutes a day is probably around the average that I might use a microwave. Maybe more.

The microwaves in a company lunchroom are probably used at about an hour a day (two shifts with 30 minute lunch breaks). That would limit their expected lifespan to about 5.5 years.

Compare your usage to these two values and you'll have an idea of how long your microwave may last.

However you generally have no idea how heavily a used microwave may have been used, how it was used or abused, or how long it might last. This might be why the local charities around here (Goodwill, St VdP) refuse to take used microwaves as donations.


Post# 526783 , Reply# 13   6/25/2011 at 02:20 (2,495 days old) by tolivac (greenville nc)        

Besides magnetron tubes in older ovens-how bout door seals-these help prevent leakage of microwave energy.If they are in bad condition--pass.Usual food grime and whatnot can be cleaned away.Don't know if older magnetron tubes for old microwaves are still available.the tube "assembly" consisted of the magnetron itself-and the HV rectifier diodes.they were built into the magnetron assembly.when the tube fails-if it shorts-the diodes fail,too.The "monitor" fuses for microwaves are required by Federal law-they are in ANY microwave.the interlock monitor fuse blows if the door interlock switch shorts,or if someone tries to defeat the door interlock and run the oven with the door open.The idea there is to disable the oven until it can be repaired.the HV rectifier capacitor was separate from the magnetron assembly.It filters some of the "ripple" from the rectified AC-and acts as a doubler device-most microwave HV transformers have sec voltages from 1000V-1200V-the tube runs about 2000-2400V and on the cathode-the anode was "grounded" to the body of the oven.the cathode besides having filament voltage on it-has the pulsing 2000-2400V on it, beware any who wants to work inside the innards of a microwave cooker!

Post# 526784 , Reply# 14   6/25/2011 at 02:27 (2,495 days old) by tolivac (greenville nc)        

another thing to think about regarding magnetron tube life--remember the tube is cycled on-off,on-off thruout its life.It is not run continuously as most other tubes are.The on-ff cycling does shorten the life of any tube.the filament is stressed-like an incandscent light bub turned on-off,and the cathode gets stressed anytime the HV supply is,a magnetron tube does lead a pretty hard life.Radar and other magnetrons are at least run for long periods of time during use.they will last longer.

Post# 526806 , Reply# 15   6/25/2011 at 07:27 (2,495 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        

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Am willing to wager many vintage microwaves saw very little use aside from the normal reheating and "nuking" certian meals. I mean really; despite all those wonderful looking dishes and recipes microwave makers churned out in cook books, there is really only a limited array of food that "cooks" well in a plain MC. Even worse early microwave ovens often cooked very unevenly. Turning a rack or plate of nibbles for a cocktail party into stuff swiftly chucked into the rubbish behind the hostess's back.

Post# 526922 , Reply# 16   6/26/2011 at 00:08 (2,495 days old) by PhilR (Quebec Canada)        

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"The on-ff cycling does shorten the life of any tube  "


Does that means that the very quick "on/off" cycling of the magnetron in my older (Frigidaire/Amana) microwave oven (when using it at less than full power) is harder on the magnetron than it would be on newer microwave ovens?

Post# 526938 , Reply# 17   6/26/2011 at 02:39 (2,494 days old) by tolivac (greenville nc)        

In most "older" microwave ovens only the HV supply was cycled on off for lo heat or defrosting.A separate transformer supplied the filament voltage for the magnetron.Another transformer supplied the HV the primary side of the HV transformer was cycled on-off or varied thru a Triac type device to provide the lo heat or defrosting,when you started the oven-the filament transformer would light the magnetron-the HV would be cycled on-off during the cook cycle.The filament would stay on during the cycle.I think newer ovens do the same sort of thing.somewhere at home have a service book on old microwaves.In new microwaves the HV would be "modulated" by varying frequency and wave duration to give the heating effects desired called for by the cooking cycles-the device there is sort of like the pulse modulator for a radar magnetron.the filament would stay on during the cycle.then switched off when the cycle was over.In radar transmitters the fil stays on until the operator turns the fil switch off on the transmitter.the switch in that case is interlocked thru the HV supplies-they are switched off,too.Good only for emergencies-you could blow the manetron in that case.

Post# 527022 , Reply# 18   6/26/2011 at 13:17 (2,494 days old) by aquarius1984 (Ripley, Derbyshire)        

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Im not so sure, confused for sure here!

I own my Grans brother hi Speed microwave which if IIRC was bought in 1992 and was used intensively for 12 years before my gran passed away. She used it to cook whole sunday roasts, meat portions, cakes, pastries, oven chips, vegetables, roast potatoes and all kinds of things.

After 2003 my grandad has used it solely for re heating meals and warming up cups of milk, and yet it still performs like its almost new from its box.

Im able to cook a whole roast chicken in 3o minutes using the Hi Speed sensor cooking and not any old chicken either, flesh soft as butter and yes the skin is golden!

Have even cooked a full meal of pork steaks, baked potatoes and roast mediterrenean veggies in around 35 minutes.

Sausages roast in 15 minutes, bacon to go with it in an extra 5 if the oven is hot. bacon placed on top of the sausages to heat off their heat.

Warms a cup of milk in 1 minute 30 seconds, about the time most modern microwaves seem to take I have found.

Looking to stock pile spares for sure, I aint taking a risk with this one, I want it for life.

Post# 527055 , Reply# 19   6/26/2011 at 16:15 (2,494 days old) by retropia (Central Ohio)        

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Robert, how does your grand dad's Brother microwave manage to brown food? Does it have a convection or broil-type heating element, in addition to the microwave?

When we someday replace our over-the-range microwave, I'm thinking it would be handy to have a microwave that also has a built-in convection baking/roasting feature.

Post# 527064 , Reply# 20   6/26/2011 at 17:17 (2,494 days old) by cfz2882 (Belle Fourche,SD)        
non-microwave heat modes

i have seen a few microwave ovens with a calrod element around the top of the oven
chamber-i have a 1985 litton with this.Haven't seen a microwave oven with fan-
forced"convection"resistance heating mode, but there might be some...

Post# 527070 , Reply# 21   6/26/2011 at 18:04 (2,494 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
Fan Forced Convection

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Since one is on the hunt for a vintage Micro/Convec oven have been pouring lots of part diagrams. So far the Thailand made Whirlpool (that Gansky had a NIB model, given to Mixfinder) is the first I've found there the heating element surrounded the rear fan for "true convection".

Every other vintage model one has looked over have just the one element in the top "roof" (Amana Radarange, Panasonic Dimension 3, and 4, for instance), others such as the Sayno built Sears Micro/Convection oven have two conceled elements, one top and the other bottom. For the later Sears had two models, the early version where the fan was located on top and blew down had two heating elements, while the later model moved the fan to the rear as well as the heater, but cannot tell if it surrounds the fan or is just built into the wall.

All microwave/convection ovens that *claim* to broil have at least the one element conceled in the top. This IMHO means the the broiling probably leaves much to be desired since the whole purpose of the process is to place food under radiant heat. The fact that the heat is now behind a metal wall of varying thickness must complicate things.

According to the cook book I have for the Panasonic "Dimension 4", broiling a steak or chops takes on average 15 minutes or so for both sides. My little vintage Toastmaster "flip" oven/broiler with the two exposed heating rods can do it at about 7min to 10min depending how you like them done.


Post# 527133 , Reply# 22   6/27/2011 at 04:18 (2,493 days old) by tolivac (greenville nc)        

I have a GE "Advantium" microwave-type oven that uses Halogen lamps as the heating elements for baking or browning, very well and FAST.The halogen elements are on the top and bottom of the oven.

Post# 527152 , Reply# 23   6/27/2011 at 07:59 (2,493 days old) by cadman (Cedar Falls, IA)        

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I have drug home dozens upon dozens of Radaranges, 95% pre 1981. Out of all of those I can think of only 1 that had a noticeable deficiency in power due to a worn magenetron. The majority needed nothing but a clean up, others a going-through of the touch-panel power supply section. Vegas can't touch those odds.

Good Radaranges can be had for much less than $100 locally; usually 20 bucks is the going rate. At those dollars rolling the dice isn't so bad. -Cory

Post# 527178 , Reply# 24   6/27/2011 at 11:17 (2,493 days old) by sudsmaster (East of SF, West of Eden, California)        

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Hey, why stop at microwave/true convection/true broil?

Why not a refrigeration mode, as well as the capability to shine your shoes?

Just kidding... but the more a product tries to cram in essentially opposite tasks, I think the more expensive and prone to failure it probably will be, as well as being mediocre in one or more of the designed in tasks.

But hey, if it keeps you young, go for it!

Post# 527231 , Reply# 25   6/27/2011 at 14:17 (2,493 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
*LOL*@ Sudsmaster

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While cannot fathom broiling in a microwave, there are those whom report excellent results with vintage and modern versions of such ovens like the Sharp model.

What I've found by pouring over owner's manuals for both modern and vintage combo micro/convection/broil ovens is the amount of time one must pre-heat the oven for functions involving heat (broiling and or convection).

To broil and or bake in convection in some older and new models you have to pre-heat for anywhere from 8, 9, 10 or more minutes. Add this to the longer broil times because the heat is indirect (hidden behind the walls of the oven) and that is allot of power wasted IMHO.

My Toastmaster broiler/oven pre-heats for broiling in about two minutes.

Post# 527241 , Reply# 26   6/27/2011 at 16:22 (2,493 days old) by sudsmaster (East of SF, West of Eden, California)        

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Well, I get by just fine with separate appliances for different functions.

GE P-7 electric (non-convection) 24" wall oven for standard baking. Works fine.

Cuisinart convection toaster oven that I use primarily to cook 12" De Giourno Supreme pizzas. Works great for that. Preheats in 5 min or less.

Two microwaves used to thaw items, heat up frozen entrees etc, reheat leftovers, popcorn, etc. Nothing fancy, but basically what these things do best. I have in the past tried using microwaves for more complex cooking (roast chicken, baked potatoes for example) but the results have never been all that great.

For grilling/broiling/rotisserie, have a propane gas grill out on the covered patio that does all that just fine without filling the house with smoke, fumes, or grease spatter. Works great grilling steaks, and also for rotisserie cooking of poultry (chicken, turkey).

For slow cooking, a Hamilton Beach 6 qt unit with temp probe. This thing works great for slow-cooked pork shoulder.

For traditional roasting, a smoker with offset firebox. Good for ribs.

For traditional coal-fired BBQ, a Kingsford "Egg" covered charcoal grill. It makes a mean smoked turkey too, but it's rather labor intensive.

Oh, yeah, I have had a few electric portable grills, George Foreman type clones, and even an electric rotisserie ("Baby George"). These work ok but the results are sort of bland and they spend most of their time in deep storage. I frankly prefer using a good frying pan for making burgers, fish, etc, and steaks in winter when I don't feel like firing up the gas grill. So easy just to pour off unwanted grease/oil if that's what you want. And in fact a good frying pan, a 3 qt covered saucepan, and a reliable gas burner or two, are all one really needs for basic but healthy cooking. I love all the gadgets as much as anyone else (and my kitchen is overloaded with them), but when it comes right down to it, those are the items one can always fall back on.

Post# 527243 , Reply# 27   6/27/2011 at 16:32 (2,493 days old) by revvinkevin (Between Mickey Mouse & the Queen Mary (So. Cal.)        

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I have the sneaking suspension that Ms. Launderess does not have the room, space or storage for so many differnt (single use) appliances! I'm guessing that's why she wants a multi-purpose tool like the combo unit....

Post# 527268 , Reply# 28   6/27/2011 at 20:19 (2,493 days old) by sudsmaster (East of SF, West of Eden, California)        

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Yes, but she lives in NYC where one can get any kind of food one might desire with just a phone call, no?


Post# 527272 , Reply# 29   6/27/2011 at 21:36 (2,493 days old) by brisnat81 (Brisbane Australia)        

Laundress, are you sure you've got the hang of the Panasonic Dimension 4 Combi's?

The one's we've always had going back as far as 1980 have had the grill element in the top which is exposed (or behind a grill), plus a hidden element with the fan for convection. The Grill element is only on when Grilling, there is a seperate element/fan for combi cooking.

The 2kw element in the Aussie ones will preheat to 180degC in about about 10 mins or so.

In Australia toaster oven's arent popular, so its a great way to get a small oven that heats up fast and combines the best of both worlds into one product.

Post# 527279 , Reply# 30   6/27/2011 at 22:41 (2,493 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
Panasonic Dimension 4 Combis

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According to the parts drawings and owner's manual I've seen for the Panni DM4 there isn't an exposed heating element. Just a grille cover on the inside top of the oven but nothing the exposed elements one is used to seeing in electric ovens and or broilers.

Post# 527413 , Reply# 31   6/28/2011 at 18:12 (2,492 days old) by brisnat81 (Brisbane Australia)        

They dont use a calrod element for the grill, most of the Japanese designs use a Quartz element (Kind of like a bar heater element) that is mounted behind the grill. It then relies on the turntable to rotate the food under the element. The Element is the hour hand from the centre to the outer edge and the food rotates under it. It doesnt heat the entire top of the microwave, only the one specific area.

The claim they make is that its isntantly hot and not reliant on heatup time compared to the traditional calrod.

Post# 527420 , Reply# 32   6/28/2011 at 18:59 (2,492 days old) by MattL (Flushing, MI)        

My Whirlpool Mico/range hood, a G3, has a halogen as well as an infrared element for broiling.  I would not broil a steak with it, but I enjoy my chicken broiled and microwave cooked with it.  The skin gets nicely crisped and brown and the inside is fork tender.   I put a Maytag Micro/Convection/oven/broiler in the house I redid a few years ago, was looking for top $$ for the place but the market crashed and I rented it out.  When the folks move out I'll pull it and pop in a cheapie and either save it for here or swap out the one I have.


There are times a small oven would be perfect.  I'm not lacking for ovens, I have 3, but they are all standard sized and at times  a quick pan of cookies or such would be nice with out running the big oven.

Post# 527447 , Reply# 33   6/28/2011 at 20:31 (2,492 days old) by combo52 (Beltsville,Md)        

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Cory is correct, in my experience MW ovens do not slow down much over thier life time. Magnetron tubes do fail and when they do it will be a dramatic slow down of cooking speed or non at all. The worst thing you can do to your MW ovens Mag tube is to run it empty or nearly so. This is why so many mag tubes fail while trying to pop pop corn as there is very little mass to the PC and you are running the oven at full power trying to heat it. Also in our experience the newer over 900 watt MW ovens are having many more failures of the Mag tube. The tubes in the newer ovens are the same size but they are working them much harder and this seems the cause them to fail faster. The newer ovens are more efficient however as they do put out more cooking power while using about the same amount of electricity as the older 600-700 watt models, but sometimes at the expense of long life.

Post# 527457 , Reply# 34   6/28/2011 at 21:24 (2,492 days old) by sudsmaster (East of SF, West of Eden, California)        

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Did some more reading.

The consensus (if the Internet can host such a thing), is that magnetron tubes can lose some of their power, but the slide is relatively small and probably undetectable by consumers.

However, the power supply (transformer) can lose its effectiveness. One poster opined that the most common way this happens is if the capacitor loses its ability to store power. This would result in the magnetron going into a pulse rather than a continuous power mode, resulting in lower average power output.

I figure the power supply/capacitor issue is probably what I've observed in heavily used older microwaves in the company lunchroom.

Another post suggested that one can measure the actual power output of a microwave oven by heating 500 ml (1/2 liter) of water for 60 seconds, measure the temperature rise in C, and multiply by 17 to get effective watts.

No I haven't tried it... yet...

Post# 527469 , Reply# 35   6/28/2011 at 22:36 (2,492 days old) by combo52 (Beltsville,Md)        

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 I do not believe that anything can or does happen to the power transformer, that makes no sense at all. That would be like an induction motor losing HP I have never heard of such a thing. The capacitor losing value is something that I am not as sure about.


MW oven power output is tested by how much it will raise the temperature of a given quantity of water in a given time. The manufacturer-or publishes this information in thier repair manuals for specific models, so it is easy to test.

Post# 527493 , Reply# 36   6/29/2011 at 01:37 (2,491 days old) by sudsmaster (East of SF, West of Eden, California)        
It seems possible to me....

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Read on...

"It is possible for a microwave to lose cooking speed. If the microwave source isn't able to produce as intense microwaves as before or if it doesn't turn on reliably and steadily, it won't cook as fast. For the source to produce less intense microwaves, the high voltage power supply would probably have to be weak. Its storage capacitor could have failed or one or more of its high voltage diodes could have burned out. According to a reader, the most likely cause of weak cooking in a microwave oven is a failed capacitor—with no ability to store separated charge in its capacitor, the oven produces pulsing rather than steady microwaves and delivers less average power. I suppose that the magnetron itself could be dying, with the most common failure (according to that same reader) being shorting out, the result of electromigration of the filament material. For the source to not turn on reliably, it would probably have to have a bad connection to the power line. One good possibility is that the relay that turns on power to the high voltage power supply is not making good contact.

"Listen to the microwave as it operates on a medium setting. It should cycle on and off every five or ten seconds. You should hear it hum softly during the on half of the cycle and then stop humming during the off half of the cycle. Different power levels simply vary the fractions of on time and off time. If you don't hear the hum or the hum is intermittent, then something is probably wrong with the power relay or with something else in the high voltage power supply. If the relay is flaky, a little cleaning of its contacts may cure the problem. Be careful of the high voltage capacitor, which can store a lethal charge even when the unit is unplugged."


Post# 527502 , Reply# 37   6/29/2011 at 02:44 (2,491 days old) by tolivac (greenville nc)        

In modern microwave there may not be a relay to control the primary power to the transformer-maybe a solid state circuit instead.Both tubes and capacitors do lose capacity.However if the capacitor or transformer has failed-usually shorted-blows the fuses inside the microwave.another thing on the magnetron-its magnet can lose magnetic power from the heat of the tube and other parts in the oven.this is minor-but can happen-Its more common on very high power radar transmitters.Microwave oven transformers rarely fail on their own-something CAUSED the transformer to fail-like a shorted cap,diodes, or tube.

Post# 527504 , Reply# 38   6/29/2011 at 02:51 (2,491 days old) by tolivac (greenville nc)        

And yes,running the microwave with no load can lead to short life of the magnetron tube.The magnetron tube has a short antenna like probe inside one end of the tube-connected to the waveguide that directs the microwave energy from the tube to the oven cooking chamber.Now if theere is no load to absorb the energy the magnetron generates-the little antenna probe heats up-and even overheats-this causes the glass seals on the probe output end of the tube to fail.-tube goes to air.end of tube.the no load condition may take some time for this to happen.

Post# 527534 , Reply# 39   6/29/2011 at 07:09 (2,491 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
For Your Wednesday Morning Reading

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Along with your coffee


Post# 527596 , Reply# 40   6/29/2011 at 11:38 (2,491 days old) by retropia (Central Ohio)        

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The 1978 Popular Science article was interesting. I remember when microwave ovens became widely available, there was a lot of concern about radiation escaping. People would try to avoid standing directly in front of one while it was on.

Further in the magazine, I also enjoyed the ad for the 1978 Ford Fairmont! While not a particularly exciting car, it was sensibly sized, fairly roomy inside and it was easy to park.

And I also enjoyed the ad for Winston Light cigarettes!

Post# 527668 , Reply# 41   6/29/2011 at 16:14 (2,491 days old) by irishwashguy (Salem,Oregon.............A Capital City)        
I had my 1976 Radar range serviced

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i had it checked for leaks and fixed a broken spring. 40 dollars later, I still have a microwave oven that works like a charm. Even better, it works as well as my Mom's new kenmore . They are built sturdy.

Post# 527748 , Reply# 42   6/30/2011 at 00:34 (2,491 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
Fairmont Easy To Park?

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Well yes, if you are used to docking the Ille de France for a living! *LOL*

Post# 527749 , Reply# 43   6/30/2011 at 00:35 (2,491 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        

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Ah the 1970's!


That  hair, those outfits!


Post# 527751 , Reply# 44   6/30/2011 at 00:37 (2,491 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
People Carrier of 1978

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Kind of looks more stylish as a wagon, no?

Post# 527856 , Reply# 45   6/30/2011 at 12:40 (2,490 days old) by retropia (Central Ohio)        

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If you've ever driven one of these, you would agree that by comparison, a Fairmont is a breeze to park, LOL. In 1978, the Fairmont was positively petite. From there you got bigger with the Granada, then huge with the LTD II, and then gargantuan with this LTD Landau 4-door pillared hardtop.

Post# 527914 , Reply# 46   6/30/2011 at 17:49 (2,490 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
Combi Units

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Was reading through an older issue of the CR Buying Guide (1983) and in general they panned combination microwave/convection ovens of the day. Of the choices (Sharp, Amana, Panasonic, Quasar), the Radarange (RMC-30) came in dead last in both microwave cooking and combi roasting beef. Apparently according to CR's tests neither the Quasar nor Amana produced even cooking with microwave power only (note these were the only two models tested without turn tables), and had various drawbacks to their convection/combi modes as well. The Amana for instance had only one preset temperature, 300F.

From reading vintage microwave service information on the web, Amana knew for awhile it's combi ovens had too low power for browning/baking. The initial models (RMC-20****) had heating elemets of only about 1300 or 1400 watts. By the time Amana changed from the Cookmatic series with dials to the Touchmatic, the new combi oven (RMC-30) had wattage bumped up to about 1500 watts.

Post# 529053 , Reply# 47   7/6/2011 at 14:50 (2,484 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
Nabbed A Bunch of Vintage Consumer Reports Buying Guides

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According to their testing, which counters what one finds here in the group, Amana microwaves weren't the best for even cooking and other criteria. It's not until about the mid 1980's that Radaranges start to pick up in ratings. Have not read everything, but it appears MCs with turntables out scored those without for even results.

Indeed Amana's "Radarange Plus RMC-30" micro/convection oven came in dead last after Sharp (top rated) and Panasonic.

CR also panned much of the "cooking" one was supposed to be able to do in a microwave oven. Cakes, meats, roasts, etc all sometimes were less than what one would expect, even when using browning devices and or coatings designed to give that effect.

Post# 529116 , Reply# 48   7/6/2011 at 19:54 (2,484 days old) by sudsmaster (East of SF, West of Eden, California)        

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As I recall, one could purchase spring-wound turntables for use in MW's without turntables. I had a small one for my mid-1980's 1 cu ft Amana (it was made by Hitachi). It cooked ok without the turntable, though - never noticed much of a difference with or without it.

The Kenmore Elite microwave I got around 1998 is fairly impressive in its attempts to even the cooking rays. There's a huge translucent amber plastic cover - about the size of a teacup saucer - with a visible rotating impeller, on the side of the cabinet where the magnetron lives. There is also a turntable. I like the impeller/magnetron cover because it's so easy to clean, and it provides some entertainment value as well.

Post# 529120 , Reply# 49   7/6/2011 at 20:56 (2,484 days old) by Launderess (Quiet Please, There´s a Lady on Stage)        
I Remember Those Turn Tables

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But as rarely used microwaves back then for more than reheating left overs,or heating water or milk never really bothered.

Again am going to wager that the reason so many of those huge work-horse microwaves from the 1980's and 1990's are still out there (by and large) in good shape is they never got much of a workout.

Housewives and whomever else tried to "cook" things in them probably reached the same conclusion as CR and moved on. For most things CR stated they got better results in their GE convection electric range/oven in the same or less time, and used less electric power than a microwave. The only exceptions would be things like baked potatoes and certain other foods.

Personally cannot imagine a meatloaf, roast beef or any other meat cooked by microwave alone. Convection/microwave yes, but not nuking by itself.

Oh for what it was worth both the Amana convection/micro and Panasonic did not fare well in CR's roasting tests. Both produced roast beef that was very rare in the center and over cooked every where else. This with the fact both ovens used temperature probes, while the Sharp didn't.

CR tested for even cooking same way as Whirlcool suggested; using slices of bread with a layer of cheese.

Strange thing: the first Amana Radarange Plus oven (with dial control) had three convection oven settings, low, medium and high. Low was really meant for using the oven as a dehydrator. Medium and high were for cooking. When the RMC-30 came out while the total watts for heating was increased, the oven temperature was set in all modes to about 300F in both convection only and combination. Both the Sharp and Panasonic could go up to 450F.

Am wondering if the "low" heating power was the reason for Amana's poor roasting results.

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