The Device that Won WW2 - The Cavity Magnetron 

It was the Soviet army that defeated the Nazis - ask the German historians. It was the Soviet army that liberated the concentration camps in Germany - ask the Jews and other prisoners freed from these evil monstrosities. The terrorist war atrocity nukings of civilian centres in Japan did not end the war. Remember, the Soviet Union lost over 25 million people in WW2. The USA lost less than 400,000 and the UK less than 600,000. There were lots of sacrifices made by many nations but lets not engage in historical revisionism and Hollywood myth.

There is no such thing as climate change. Please stick to the science and don't spew PROPAGANDA

ProtonVPN is way better, nordvpn is no good for Arrrrrrrrrrrrrr.

You switching between talking loudly and then going back to nearly whispering makes it hard to follow the video.

thank goodness that thing helped win the war. It would’ve been horrible if Europe would’ve remainded European. London would still be English. One shudders to imagine the horror

That is a great story. Thanks for sharing.

Yeah great addl background, I play guitar and Tubes are still the best organic tone, so sorry the US lost all this special stuff..

we designed and manufactured microwave tubes; magnetrons, cross field amps, klystrons, TWTs at Microwave & Power Tube in Waltham Ma Raytheon was in the comsumer tube business in the "early days" but that was long over when I got there in 1967. I designed factory test equipment for the Tube Group. There was an attempt to make microwave oven tubes there but that failed because that was a different "culture" from miltary contracts and we couldn't compete with the off shore manufacturers. I will only use tubes in my high power Ham station amplifers, 73 Mike, K1FNX @@skeeterbodeen8326

I asked Percy about this and he said he never met you

QSL, it's been a long time and I'm sure his memory isn't what it used to be @@user540000

That was the 'magic sauce' for mass production. I've taken apart modern heating type magnetrons and they don't look precision. Would love to know if that is just due to the lack of need for a precise output frequency, or just design improvements.

@@clytle374 the magnetron in microwave ovens don’t need a narrow frequency spectrum. They’re not measuring return pulse time, just jostling water molecules.

Yup, I learned that from Bill Hamac's recent video (Engineerinf Guy)

@@norlockv They oscillate at the resonant frequency of water. This is what jostles the water molecules. Very sorry, what I read was wrong, so I was wrong. Here is the correct information: Quote: A study of a typical household microwave oven conducted by Michal Soltysiak, Malgorzata Celuch, and Ulrich Erle, and published in IEEE's Microwave Symposium Digest, found that the oven's frequency spectrum contained several broad peaks that spanned from 2.40 to 2.50 GHz. Furthermore, they found that the location, shape, and even the number of broad peaks in the frequency spectrum depended on the orientation of the object that was in the oven being heated. In other words, the exact frequencies present in the electromagnetic waves that fill the oven depend on the details of the food itself. Clearly, the microwaves cannot be tuned in frequency to anything particular if the frequencies change every time you heat a different food. Unquote. And the reason for the frequency, is so the FCC has that classified for microwave ovens. Thanks to the more 'educated' responders in setting me straight. 🤒

@@David-yo5ws Nope, that's not what's going on, and not true.

Was he cute?

@@retiredbore378 My dad worked for IH and my Granpa Deere they had some interesting breakfast conversations over the years. My dad was part of the team that invented the hillside combine and 2+2 tractor, I don't know if it was just him or a big team. Glad you are enjoying retirement.

@@SunBear69420 no

As he should!

My grandfather worked on the magnetron project during the war. He told us that he dropped the first prototype and broke it lol. His name was John Linsley-Hood.

I have a Husqvarna microwave oven from 80´s in my kitchen, and still works reliably. Made in U.S.A.

It's kind of Lovecraftian, actually. Lovecraft stories often feature geometric shapes that make people insane by looking at them or which channel energy and open portals to other dimensions.

Like Wacław Struszyński antena for: "High-frequency direction finding, usually known by its abbreviation HF/DF or nickname huff-duff, is a type of radio direction finder (RDF) introduced in World War II. High frequency (HF) refers to a radio band that can effectively communicate over long distances; for example, between U-boats and their land-based headquarters. HF/DF was primarily used to catch enemy radios while they transmitted, although it was also used to locate friendly aircraft as a navigation aid.(...) Land-based systems were used because there were severe technical problems operating on ships, mainly due to the effects of the superstructure on the wavefront of arriving radio signals. However, these problems were overcome under the technical leadership of the Polish engineer Wacław Struszyński, working at the Admiralty Signal Establishment. As ships were equipped, a complex measurement series was carried out to determine these effects, and cards were supplied to the operators to show the required corrections at various frequencies. By 1942, the availability of cathode ray tubes improved and was no longer a limit on the number of huff-duff sets that could be produced. At the same time, improved sets were introduced that included continuously motor-driven tuning, to scan the likely frequencies and sound an automatic alarm when any transmissions were detected. Operators could then rapidly fine-tune the signal before it disappeared. These sets were installed on convoy escorts, enabling them to get fixes on U-boats transmitting from over the horizon, beyond the range of radar. This allowed hunter-killer ships and aircraft to be dispatched at high speed in the direction of the U-boat, which could be located by radar if still on the surface or ASDIC if submerged." From August 1944, Germany was working on the Kurier system, which would transmit an entire kurzsignale in a burst not longer than 454 milliseconds, too short to be located, or intercepted for decryption, but the system had not become operational by the end of the war.

It's so cool, stuff like HAARP is jsut a bunch of wires arranged In a certain way that if you put power threw the wires in the right frequency you can heat up the ionosphere

And their shape gives them funny 'adopted' names. Like the early curved RADAR structures being called a 'Dish'. And a big rectangular rotating structure was called the 'bedstead'.

Circular shapes are the most efficient that's why they are used, they are not solid first, and the amounts of space inside can be magnified by various methods, look into night vision scopes for example

Atom Bombs was one of the other things he was involved in , the man who most likely kicked off the Manhattan project when he sat in on one of the US Uranium Committee meetings and asked, Haven't you guys read the MAUD report???.

Less the Elephant in the room. More of an Oliphant in the Laboratory. Yes, I keep pachyderm puns in! A mammoth tusk indeed.

Another unrecognised Australian.

Not in his home state, South Australia. Knighted in 1959 Sir Mark Oliphant became Governor of SA in 1971 @@Skipper.17

Wish people would listen to interview with Mark Oliphant

Well if it was tomato soup, I am sure his face was redder. 😳

Put a tin of tomato sauce in a conventional oven and the same thing will happen.

Try a sausage without puncturing the casing. What a mess!

@@musicbruv Open fire will do it as well. Back in 1992 I saw a guy heat a can of chicken frikassé over a Hexamine solid fuel burner without opening it. Pretty amusing sight though when that thing popped open :D

Well, it was '73.

No clue what you just said but wafers are cool. I eat them sometimes. With cream cheese. Or regular cheese. I like cheese too.

@@davidtatum8682 LOL! Semiconductor wafers is also safe to consume with cheese!

@@manishsakariya4595 good to know. I'll try it.

​@@manishsakariya4595but they are really crunchy....

I used to do epitaxial growth on indium phosphide wafers and now I change magnetrons in people's microwaves for a living, among other things. Turns out randos who want their kitchen fixed pay more than fortune 500 companies that require you to hand pour HF for a wet etch process. Go figure.

It would have been great if it were under different circumstances where we all weren't trying to kill each other. I get what you are saying though. War time usually leads to technological advances.

That's the only good thing that comes from war. Rapidly accelerated technology development. Right for the wrong reason.

The relevance is important.

Well then, yer simply gonna be ecstatic to see what single handedly won World War Three!

@@slugface322 we all know it's AI already

-The Japanese Yoji Ito and colleagues) (invented a multi-cavity magnetron with circular cavities and narrow slits about 1 year before the British (Randal and Boot) and also developed strapping. They made and operated several 10cm radars by 1942. They started with magnetrons with square cavities and refined the process of understanding. The Germans Sanitas Company had a 2kW 22cm multi-cavity magnetron by 1939. There is a nice paper by "Doering" on German microwave tube development (costs about $25) which has a picture of a German magnetron with circular cavities and narrow slits by the company Lorentz. It was only small device. -The Germans did have a microwave program. One targeted 25cm wavelengths using the LD6 and LD7 disk triode which could produced about 30kW - 50kW pulses. This device could produced coherent pulses for use in Doppler radar. The other targeted 5cm using a tunable split anode magneto of about 1kW. -In 1942 the Germans decided they didn't have the resources to develop microwave radar and that their existing radars were adaquet and so the program was disbanded with many of the engineers and technicians going to the Army. When the British H2S CV64 Magnetron was recovered at the end of 1942 the experts had to be brought back together. LD6 and LD7 development continued because of the 27cm FuMO 231 Euklid fire control radar for the German Navy. The LD6 could produce a 16kW pulse at 9cm so it was competitive with the first generation of British H2S magnetrons but with the advantage of being coherent. .

​@williamzk9083 Wow! This response contained more detailed information than the video. Thank you!

Lol you said load

A lossy RF cable is a brilliant way to transfer the RF energy into thermal energy. High power RF attenuators would surely be rare and expensive in those days.

thats interesting

@ProfSimonHolland i also found their statement to be interesting.. Especially the part where they said, "Load"... 😄

@@SunBear69420 quite revealing

By Merrill Skolnik, perhaps? Maybe not. I think his book was called _The Radar Handbook_.

Fort Bliss ?

@@finddeniro Ultra Electronics in London

I was a kid in those days too and a bit of a mad professor. I remember we could buy X-ray tubes from advert's in electronics magazines and electronics surplus stores. Soooo dangerous, luckily I wasn't interested in them.

Do you both have cataracts now?

@@Chad-Giga. No cataracts, but I do need reading glasses.

"The Secret War" 😍😍

The Secret War is awesome. 1970s documentary featuring a lot of interviewees from both the UK and German side about WWII high tech. I had to go to Daily Motion to find the episodes, I think RU-vid takes them down.

@@RCAvhstape I've watched all of them. 😁

My dad (Okinawa) gave me Winterbottom's book on the code war not too long after it was published in paperback.

yes....this is a fascinating story

That was done by Maurice Ponte. When the Germans invaded France he went to Britain and gave his information. Dutchman Klaas Posthumus who worked for Philips did research and wrote theoretical articles before the war and so helped Randal and Boot of Birmingham University with their thinking.

I had to go look this up. Magnetrons operated at extra high voltages do generate electrons that generate "breaking radiation".

@@jamallabarge2665 As I said, magnetrons are still widely used today, in new treatment machines. Typical energy of the resulting xrays is about 5 MeV.

@@jamallabarge2665 Was just going to say it would have to make use of bremsstrahlung.

This was a great video, I thoroughly enjoyed it. I worked on Radiotherapy machines for many years. The magnetron is used to generate high power microwave RF (travelling wave) within a tuned linear accelerator (Linac) structure. Note that the RF is used simply to accelerate electrons, so does not generate X-rays directly (at least not on medical Linacs that I know of). Electrons from an electron gun are injected into the linear accelerator at the point where the RF enters the linear accelerating structure. The electrons are initially bunched into packets and "surf ride" the RF wave, accelerating to near light speed, gaining 7x their rest mass in the process. Near the far end of the accelerator, any unused RF is recycled and sent back to the input, or dumped if not required. However, the accelerated electrons continue on their accelerated trajectory. The accelerated electrons then pass through a bending magnet (narrow band energy filter). The bending magnet does not allow electrons that are too low, or too high in energy to pass through. Only those electrons that make it through the bending magnet are at the desired energy for clinical treatment. They then collide with a water cooled tungsten target. These collision cause electrons in the tungsten atoms to jump to higher orbits, then drop back down again, giving off excess energy in the form of a photon in the X-ray spectrum. Final note: You can also have Linac that uses a standing RF wave, rather than a travelling wave.

Great video here for anyone that is interested. I used to work on these machines. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-jSgnWfbEx1A.html

In 1980 at the RIMPAC exercise's, our 'old tech' ship was in Pearl Harbor and I got the chance to go on a shakedown of an advanced US satellite ship. In their RADAR room, they had this high tech klystron. I said "What do you do when you want to change the klystron frequency?" The Radio Engineer said "We just turn this switch here. We can change up to 12 frequencies and set it to change every rotation too." I said, "Well we have to pull out the spare one from it's wooden box, swap it out with the operating one. Then we have to get a book out and run it through the coarse tuning by turning a wheel and watching a dial, then fine tuning. That takes us about 10 minutes at best speed." It was a real credit to American advancement. However, on exercise, we had an old low frequency RADAR, that we were not allowed to use, because the Americans could not jam it. So, we snuck in an occasional 1 scan. They would be able to pick-up we used it, but of course we could not 'confirm or deny' it was operating. Fun and games is great in peace time.

I thought it was the enigma code breaker alan turin ' but your right ' the say eveything won it ' i suppose we all played a huge part ' ie soldiers ' their only remembered with a gravestone' & not a knighthood 🤔

The copper in it might be worth about US$80.00 if you were willing to strip it down. But I think if you put a fish tank inside it (don't turn it on 😉) it might make it a great talking point about the ol' Amana.

My Mother bought an Amana Fridge / Freezer about 40 years ago ** from a London department store which is still in use today (she's 98) here in the UK. A Thermador microwave oven came with it free of charge ! It had no turntable but instead had a slowly rotating `stirrer' mounted in the roof I assume to scatter the energy. There was a rudimentary grill IIRC. ** The technician who used to look after it said they no longer last like this one, advising he had to replace a compressor after only 6 years of service recently (this is about 10 years ago). May be due to the new green refridgerants ? or they just decided they were lasting too long.

Amana was the brand name used by Raytheon for the microwave ovens.

Does it have one large dial on it ?

yeah, and how much of it is going to be destroyed by the next one…

@@marklewus5468You sound like fun!

they say war brings death... the unsung part of war also brings lots of technology research money grants. Because there's no better way to innovate technologies than to simply propose to a prospective government the possibility for a fancier stick and rocks to kill the other with. Albeit something that can be resolved culturally and not hardwired into us. \o/

Then you should be even more amazed by what was developed during the race to space - Gemini, Apollo, etc.

Nobody notices millions of inventions during peacetime, but they're just as important. Nobody notices all the inventions that weren't created, because the war effort sucked up all the money and resources.

King 🤴 klystron 🙏

Essentially that's the earliest example of spread spectrum transmission, even if that was never the intent.

FM lonlinear modulation.

Another advantage of the klystron is that you can tune the cavities to a single frequency and get LOTS of gain in a narrow frequency OR stagger tune them for increased bandwidth at the cost of gain. Klystrons, however, are not used much in radars today because mechanical tuning does not lend itself to rapid electronic tuning.

@@cancermcaids7688 I just preferred "Miss Shilling's Orifice" to "Mr. A. Hull's Cavity"! But whatever floats your boat mate! 😆

Yes, and home of the Tech Model Railroad Club and the first hackers at MIT.

It's not that recovering a crashed vehicle from the sea was impossible back then - but it's a difficult and time-consuming operation which isn't particularly practical in war-time. A U-boat trying to salvage tech from a crashed bomber is easy prey when another bomber comes along to see what happened to his buddy...

@@cancermcaids7688 I was assuming the case of a plane which had crashed - shot down by a U-boat, perhaps - but not yet sunken. Yeah, once on the bottom of the ocean, no chance of recovery even in peace-time conditions...

While he may have been hidden away for war work, I doubt there was much connection between his TVs and radar, other than the TV transmitters were "borrowed" for early radar work. His invention was using a spinning disk, with holes in it, to scan an image.

@@James_KnottYes, but that bears a fair amount of resemblance to the way older analog radar systems synchronize the antenna, pulsing, and display. So it's a fair question.

One of the first microwave ovens used in the home was accurately named the "Radar Range" made by Amana.

What rightly angers many Brits is with how much we "gave" to the Americans to ensure victory in the war, we were still demanded to pay back all the war loans while Germany got debts forgiven and even assistance rebuilding to the country it is now. The Americans took advantage and then tried for the next 70+ years to claim they were the sole reason Germany didn't win the war.

@@Reinforce_Zwei Why do you think the Americans took so long to enter the war? it wasn't isolationism, they wanted the rest of the world on its knees so they could come in and take over. A state secret that will be kept classified for centuries.

In return, the US destroyed the German wolfpacks, ensuring delivery of lend-lease aid, and manufactured useable radar at industrial scale for use by Britain. I'd call that a fair trade.

@@Reinforce_Zwei The US could have stayed home and sat out the European war instead.

@@Reinforce_Zwei Brits paid only 10% of the value of Lend-Lease program and finished doing it after 50 years... As a Polish i can say that our inventions that came to Britain and saved British are not even mentioned by British or they are even blatantly reclaimed as British invention. Preaty sure no one knows: about Wacław Struszyński Huff-Duff antena(or its importance)... Or even Marian Rejewski, Jerzy Różycki and Henryk Zygalski work and how they made working copy of Enigma and first devices able to find daily keys for it and how all that know-how ended up in Britain... Any idea who invented hand held mine detectors used by alies in wwII? As an early show of British gratitude Polish soldiers were not even invited to 1945 London victory parade... Poland was sold to stalin and he took all reparations for Poland from Germany and not allowed Poland to be part of Marshall Plan, that btw you were happy to remove from your story as it provided a loot to post war Britain aka would contradict your biased story... Only Polish soldiers were fighting in september 1939 and when Adolf was makind the decision to end himself only Polish and soviet soldiers were fighting in Berlin(and in 1939 soviet soldiers were fighting on axis side...). I am also preatty sure that German logistics was destroyed by Polish Home Army in decisive moment of wwII(German forces about to conquer Moscow) not by British and British ofc repeating the fake "Russian winter" story.

I know people that do not eat junk food => do not have it in the kitchen...

@@Bialy_1 What has junk food got anything to do with a microwave oven?? Smh!

​@@jayytee8062Everything.

​@@Bialy_1We are among those.

Also penicillin

I agree - The pace and the tone of the presenter is superb

@@buddhistsympathizer1136 exactly. My users actually walk away with an education after I present this to them. To be honest this production is so good it should be broadcasted as a TV show like on the BBC or on American, Australian and Canadian TV. 🇦🇺🤝🇺🇸✌

​@@TheSunnyvaleTrailerParkAgreed but this and a small few other channels are too good for today's TV. To thrive there you need to be an idiot.

Yes I thought that too What will be coming from Ruzzia, Ukraine war Drones have taken a large leap already

It's the power of competition at it's finest and most extreme, trying to do better than someone else when your life is on the line is a massive motivational factor for many developments.

​@@leehotspur9679 It's sort of the other way around. The commodification of drones and commercial access to parts revolutionized the use of drones in warfare.

yes...the colt revolver barrel was used as a machine tool but the sheet metal stamped idea was brilliant

It's not right to mock those that came before us. We stand on their shoulders (to borrow a quote from Sir Isaac Newton). In a few years time our present day cutting edge stuff will feel the same... Primitive.

One of the early microwave ovens used in the home was accurately named the "Radar Range" made by Amana.

British technicians long knew of the warming effect of microwaves. They often would warm their lunch by leaving it near the magnetrons.

There was also the Dieppe raid, where part of the mission was to get info from the German radar site at Pourville, in August 1942. That was conducted largely by Canadians.

@@James_Knott Quite accurate James. The raid only partially succeeded, however. The attacking party of about 10 went up against a blockhouse fortified by machine guns at every window. The raid at Bruneval (Feb 42) alerted the Germans to the need to fortify radar installations near the coast, a fact which the Allies did not consider in planning Dieppe. The Dieppe raid was in planning for too long, had too many objectives in a complicated operational plan hundreds of pages long. I believe the raid at Dieppe was so convoluted as to hide its real purpose, to steal another radar set. The stated official objective, to see if Canadians could directly take a port city for a day, and then give it back simply does not make sense. In any case, radar was top secret so you wouldn't explain to the public why you planned a huge raid to steal a set at the cost of 5,000 Allied soldiers. At least they learned a few things, but in general Dieppe was a disaster. For the most part this cannot be put on Churchill's shoulders, it was Mountbatten that ran that shit-show from start to finish.

I always wonder if that's a true story, i'm very skeptical... That story must be morphed from stories of techs sharing experiences of feeling heat in front of a microwave transmitter. There is no way no one noticed it had a heating effect until chocolate melted... you and the chocolate would feel that same heat.

@@volvo09 yeah I’m sure it’s broken telephone to some degree. I think the foil wrapper around the chocolate may have had something to do with it as well.

It was actually more complex than that. The melted chocolate story was made up by a Readers Digest writer in the 1950’s. They first noticed that you could warm your hands up from the microwave energy, and it branched off from there. Spencer and Raytheon were initially focused on heating food, but on an industrial scale. The first microwave oven in 1946 was the size of a single door fridge, and consumed 3kw of power. The modern magnetrons and microwave ovens came from the New Japanese Radio Company that developed cheap magnetrons that could cook food with less power. Nowadays there are many applications for microwaves, such as industrial drying and curing of products from lumber to ink drying, to medical uses like synthesising organic compounds. Bill Hammack goes into greater detail in his book and video series; The Things we Make

​@@tfrowlett8752yup, that was mentioned by Bill Hamac (Engineering Guy) in his video on how the design of the cavity magnetron was iterated from prototype, to a mass produced equipment for aircraft, and the one in the microwave oven.

@@tfrowlett8752 Ty!

It was a Mounds bar Cuz Almond joy has nuts Mounds don't

You know what newton ring are and why microwave cooker need to rotate🥱 Doubt you know

@@kwestionariusz1 Standing waves have no relation to why this story is bunk.

It does not take much energy to melt a candy bar w microwaves. Cadbury egg liquifies in under 5 seconds and can be very hot.

No, you're thinking about a VCR....🤨

I have never seen a kitchen with a billion cavity magnetrons in it. Perhaps the bigger catering companies might have such kitchens, who knows.

Fortunately mine has cancel which blanks out the clock. Just the timer displays. I have a real big clock, I don't need those tiny numbers to reset twice a year as well.

​@@otpyrcralphpierre1742I realise I'm getting old when I see such technologies come and go.

I think probably the Chinese are doing that kind of production technology work today.

@@philiptownsend4026 Back then, numeric control milling and lathe systems were a glimmer in the engineer's eye. It was not until the late 1940's when something barely resembling the turret mills and lathes of today came into being, but didn't sport the precision necessary for magnetrons or nuclear weapon components. But they could reproduce with cost efficiency. The Chinese poached tech from one country or another to get where they are today. Their CNC mills are Pakistani, with German software and controls. The rest is polish and duct tape. The magnetrons are an excellent example of die an tooling to make volumes of components, reliably and quickly. They didn't need high tolerance, but high production numbers. If a die develops a flaw and is picked up, that whole batch was scrapped. Just about the only component in the old style maggies they had to pay attention to was beryllium. Dust from that stuff-instant lung cancer. Modern units don't use as much of that toxic metal back then, but it's smart not to tear one down because of it.