3) Broken magnet{s} (corollary to overheating).

HP I say u should explain how broken magnets only make tube act _shorted_ cuz w/o magnetic field it's just fwd biased high vacuum diode So I've seen microwave oven transformers violently burn up cuz of that but tube was still totally reparable just by replacing magnets! But for magnets to break either TCO is stuck on or there's manufacturing defect in magnets cuz tube shouldn't be getting that hot!

Anyhow @Acrimonious Mirth plz look on tube to see if magnets are broken (which is easy to see cuz magnetic repulsion separates pieces) cuz if broken magnet is problem and new fuse doesn't open that means rectifier or transformer is burned open by high current and if there's no odor or charring on xfmr windings then all u have to do is replace rectifier and magnetron! Also u can do it super cheap by just replacing broken magnets with magnets salvaged from junk tube but just make sure to keep track of magnetic polarity of original magnets on tube ur repairing!

 

I just wanted to see something go phut, but it didn't

IanField I say 2 do that u need to put sealed glass bottle of H2O based liquid in oven with timer set for like 30 minutes push start and run like hell!

So here's totally serious disclaimer! I'm joking cuz actually doing that is a good way of getting killed, jailed or permanently disabled! I personally know an idiot who totally blew up his garage with a bottle of Cold Duck that way! It's like retro PSA's are always saying _never underestimate the power of steam_ So o/c smart ppl like veteran AACers know _power_ actually derives from energy causing state change but we don't need 2b bumptious little i-dotters and t-crossers abt it!

 

IanField I say 2 do that u need to put sealed glass bottle of H2O based liquid in oven with timer set for like 30 minutes push start and run like hell!

So here's totally serious disclaimer! I'm joking cuz actually doing that is a good way of getting killed, jailed or permanently disabled! I personally know an idiot who totally blew up his garage with a bottle of Cold Duck that way! It's like retro PSA's are always saying _never underestimate the power of steam_ So o/c smart ppl like veteran AACers know _power_ actually derives from energy causing state change but we don't need 2b bumptious little i-dotters and t-crossers abt it!

Some spoof science tv show dis a bottle of champagne - in a field powered by a portable generator. The microwave oven did a pretty impressive "soggy cardboard box". Cooking an egg without the right precautions can take the door off a cheap & nasty model.

 

HP I say u should explain how broken magnets only make tube act _shorted_ cuz w/o magnetic field it's just fwd biased high vacuum diode

I should have thought that much was obvious?

HP I say u should explain...

But then it seems you just did...

I personally know an idiot who totally blew up his garage with a bottle of Cold Duck that way!

IIRC He resorted to filling the neck with high-temp epoxy by way of preventing the cap venting prior to disruption of the glass -- A true man of 'genius' to be sure

Cooking an egg without the right precautions can take the door off a cheap & nasty model.

Eggs can indeed be 'nasty' -- but water solutions, etc in well sealed, heavily constructed glass vessels are --not uncommonly-- the 'living end'

Best regards
HP

PS -- It is hoped that the linked video will serve to discourage reckless 'experimentation' of this sort... To anyone believing (super-heated) steam-driven glass 'shrapnel' constitutes a 'prank' -- You may rest assured, it won't end 'funny'!

 

I should have thought that much was obvious?


But then it seems you just did...


IIRC He resorted to filling the neck with high-temp epoxy by way of preventing the cap venting prior to disruption of the glass -- A true man of 'genius' to be sure



Eggs can indeed be 'nasty' -- but water solutions, etc in well sealed, heavily constructed glass vessels are --not uncommonly-- the 'living end'

Best regards
HP

PS -- It is hoped that the linked video will serve to discourage reckless 'experimentation' of this sort... To anyone believing (super-heated) steam-driven glass 'shrapnel' constitutes a 'prank' -- You may rest assured, it won't end 'funny'!

My first ever uW didn't cost me a penny - the exploding egg trick was pretty much first on the agenda.

Free because the dielectric window on the waveguide had arced - I just removed it.

A chunk of exploded egg landed in the waveguide and overloaded the magnetron - I was then looking for another free uW.

 

I had a NORELCO brand microwave oven that lasted about 25 years with daily use. But never for defrosting. It never failed on me, although I did replace the fuse a couple of times. I was talked into replacing it with a more modern piece of junk that just outlasted the warranty, even though that old one still worked well.Since then it has been a steady stream of replacements. Worse, that new Toshiba inverter unit suffers from mechanical wear of the door mechanism. Fuses do fail occasionally for no obvious reason, at least that has been my experience with microwave ovens. And the earlier ones were of FAR BETTER quality, although fewer features. QUALITY IS NOT THE SAME AS FEATURES, no matter what the idiot sales person claims!!!

 

I had a NORELCO brand microwave oven that lasted about 25 years with daily use. But never for defrosting. It never failed on me, although I did replace the fuse a couple of times. I was talked into replacing it with a more modern piece of junk that just outlasted the warranty, even though that old one still worked well.Since then it has been a steady stream of replacements. Worse, that new Toshiba inverter unit suffers from mechanical wear of the door mechanism. Fuses do fail occasionally for no obvious reason, at least that has been my experience with microwave ovens. And the earlier ones were of FAR BETTER quality, although fewer features. QUALITY IS NOT THE SAME AS FEATURES, no matter what the idiot sales person claims!!!

My longest lasting uW was left in the flats corridor - some muppet wired the plug for a live casing.

It eventually rusted through where the wonky dish wore through the paint. It was like: "that's dangerous".

An LG from the bin room - a bit scruffy, only needed a bulb replacing.

 

It eventually rusted through where the wonky dish wore through the paint. It was like: "that's dangerous".

Indeed! I'm familiar with that 'symptom' <<CONTEXT>>

Best regards
HP

 

Indeed! I'm familiar with that 'symptom' <<CONTEXT>>

Best regards
HP

Looks similar build - was that a Hitachi too?

 

Looks similar build - was that a Hitachi too?

IIRC 'twas an "Emerson" (whoever the H. they are)

ETA: Yup! My jaded recollection was correct! -- Here 'tis from my linked thread:

4) Whoever 'Emerson' is they (To render John Cleese), deserve a 'thorough, rollicking spanking'

Best regards
HP

 

Oh Wow!!
But I am still wondering about the combination of MW oven with a grill. The design that we came up with had a large feed horn pointing down over a ring of fire bricks supporting a grill made of glass rods. The feed horn would look like a smoke catcher, but the big waveguide was the giveaway. The magnetron was from a ship-board high powered radar system. It would have been able to cook a steak in less than a minute. The flaw was with getting the power supply for the 120KW magnetron tube. The other problem would be getting a 120 KW plug-in connection to power the thing. Also, there may have been an issue with stray RF. But it was a fun exercise.

And I still wonder about an actual grill/MW oven combination.

 

The magnetron was from a ship-board high powered radar system.

Yebut what was its wavelength of operation? -- Please be advised that what's efficient/effective for various RADAR installations mightn't be efficiently applied to 'RF heating' of food/organic tissue in general...

In any event it is a certainty that ---at the UHF frequencies (λ≈12cm) employed in ISM RF heating applications (including standard 'microwave ovens')--- 120kW RF output is 'overkill on steroids' - even applied to so 'robust' an application as that described...

Very best regards
HP

 

Yebut what was its wavelength of operation? -- Please be advised that what's efficient/effective for various RADAR installations mightn't be efficiently applied to 'RF heating' of food/organic tissue in general...

In any event it is a certainty that ---at the UHF frequencies (λ≈12cm) employed in ISM RF heating applications (including standard 'microwave ovens')--- 120kW RF output is 'overkill on steroids' - even applied to so 'robust' an application as that described...

Very best regards
HP

YES INDEED!!! It was a bunch of superheros sitting around a grill after a long week and not being very careful with design safety. The radar system that included that particular magnetron was well known for killing seagulls that flew through the beam, and so it's ability to cook was thus "verified." The additional warnings for all to stay clear of the beam were additional "proof" that it would work. The year was 1968, the location was in another part of the world. I have no idea as to where the design sketches went, I never had them in my hands.

 

Yebut what was its wavelength of operation? -- Please be advised that what's efficient/effective for various RADAR installations mightn't be efficiently applied to 'RF heating' of food/organic tissue in general...

In any event it is a certainty that ---at the UHF frequencies (λ≈12cm) employed in ISM RF heating applications (including standard 'microwave ovens')--- 120kW RF output is 'overkill on steroids' - even applied to so 'robust' an application as that described...

Very best regards
HP

It was a melted candy bar in someone's shirt pocket as they walked in front of an aircraft radar that gave the game away.

 

It was a melted candy bar in someone's shirt pocket as they walked in front of an aircraft radar that gave the game away.

https://www.businessinsider.com/how-the-microwave-oven-was-invented-by-accident-2015-4
Max.

 

YES INDEED!!! It was a bunch of superheros sitting around a grill after a long week and not being very careful with design safety. The radar system that included that particular magnetron was well known for killing seagulls that flew through the beam, and so it's ability to cook was thus "verified." The additional warnings for all to stay clear of the beam were additional "proof" that it would work. The year was 1968, the location was in another part of the world. I have no idea as to where the design sketches went, I never had them in my hands.

It was a melted candy bar in someone's shirt pocket as they walked in front of an aircraft radar that gave the game away.

While clearly, sufficiently high-level electromagnetic radiation of any wavelength will produce heating in nearly any substance (whether by dielectric loss, molecular excitation, induced 'eddy currents' or mere absorption) -- My point is merely that efficacy is a 'function' of wavelength and material -- Specifically: it is my assertion that an adequately matched, directional radiator excited by electrical energy at a power level of 120kW in the 'vicinity' of ISM-7 (i.e. λ, F = 12cm, 2.45GHz respectively) would likely produce an effect reminiscent of that of a 'phaser set on kill' upon organic matter in the EMR beam/lobe out to a scant few tens of wavelengths!

Best wishes for a pleasant and productive new year!
HP

 

While clearly, sufficiently high-level electromagnetic radiation of any wavelength will produce heating in nearly any substance (whether by dielectric loss, molecular excitation, induced 'eddy currents' or mere absorption) -- My point is merely that efficacy is a 'function' of wavelength and material -- Specifically: it is my assertion that an adequately matched, directional radiator excited by electrical energy at a power level of 120kW in the 'vicinity' of ISM-7 (i.e. λ, F = 12cm, 2.45GHz respectively) would likely produce an effect reminiscent of that of a 'phaser set on kill' upon organic matter in the EMR beam/lobe out to a scant few tens of wavelengths!

Best wishes for a pleasant and productive new year!
HP

Likewise, HP. I just returned home from a visit to family in Minnetonka, a suburb of Minneapolis.

 

it is my assertion that an adequately matched, directional radiator excited by electrical energy at a power level of 120kW in the 'vicinity' of ISM-7 (i.e. λ, F = 12cm, 2.45GHz respectively) would likely produce an effect reminiscent of that of a 'phaser set on kill' upon organic matter

HP I say it would be way grosser than that! Cuz I say it would just reduce it to greasy, charred, arcing, flaming cinder with _delicate aroma_ of pyrolyzed cysteine! I say is hilarious how totally getting rid of something is exactly same problem as over-unity and like that for exact same reason! Now being practical it's totally possible to heat something to point of breaking it down to constituent elements in gaseous phase and so scattering it to _four winds_ as gas and suspended dust and droplets (depending on STP phase of elements and re-formed compounds after cool down) but when u do the math it takes a LOT of energy!

PS being clear: Whenever I say _over-unity_ is impossible I'm also counting energy equivalent of all mass involved! So even though that doesn't directly apply 2 this post, I say it's important disclaimer to prevent gainsayers claiming fission and fusion reactions break conservation laws which o/c they don't!

 

Max, seeing a seagull zapped in front of one of the large flat-panel beam steered arrays is enough to convince any young sailor to stay clear. It was also enough to convince the marines being transported to stay clear. And even the special ops guys decided that they would avoid that area. Later it came out that the radar power was much higher in order to detect "smaller things". And much later I discovered that it must be in the megawatts, based on the power feed to the radar set.

 

And much later I discovered that it must be in the megawatts, based on the power feed to the radar set.

---Emphasis added---

Surely, you're referring to very low duty-cycle burst operation? (if so, Joules per pulse please?) -- Else the vessel must have been a reasonable facsimile of a floating 'Con Ed' station!

Best regards
HP