The Device that Won WW2 - The Cavity Magnetron

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It's said that the atomic bomb ended WW2 but the Cavity Magnetron won the war. The invention of this palm-sized device gave first the British and then the Americans a microwave radar generator that was 1000 times more powerful than anything they had before and enabled small high power radar to be fitted to planes, ships, and vehicles. This transformed the war and swung it for the allies in Europe and the US in the pacific. This is the story of the Cavity Magnetron.
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Written, Researched and Presented by Paul Shillito
Images and footage: Images and footage : US DoD, US Navy, Raytheon, MIT,
And as always a big thank you also goes out to all our Patreons :-)
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[@CuriousDroid]

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[@PetraKann]

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.

[@guff9567]

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

[@toxlaximus3297]

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

[@graealex]

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

[@knuthamsun6106]

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

[@michaelpolimer2128]

I started working at Raytheon in 1967 at the old Microwave & Power Tube plant in Waltham Ma. Percy had retired by that time but he still maintained a lab at his home in Newton Ma and would call my boss for parts he needed for experiments. I used to drop them off on my way home. He was an interesting guy. The plant was full of old WW2 & Korean War tube production equipment which we occasionally had to get up and running so we could produce replacment tubes for equipment still in use. It was an "electronics museum". There were some areas which were just as they were in 1945 until Raytheon went out of the microwave tube business in abt 1993. I stayed with Raytheon until I retired in 2010 and could be the "last link" to Percy at Raytheon.

[@vincentsutter1071]

That is a great story. Thanks for sharing.

[@skeeterbodeen8326]

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

[@michaelpolimer2128]

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

[@user540000]

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

[@michaelpolimer2128]

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

[@NonEuclideanTacoCannon]

I always love small, solid objects that do something neat with physics just by the way they are shaped.

[@RCAvhstape]

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.

[@Bialy_1]

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.

[@christianterrill3503]

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

[@David-yo5ws]

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'.

[@shable1436]

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

[@Lone_wolf--br7fi]

So basically I can build a radar from my microwave

[@nole8923]

This guy looks like the bad guy in a James Bond movie.

[@norlockv]

A part of this story I found enlightening was that the US manufacturing engineers changed their manufacturing from a high precision milling operation to a metal stamping job. They stacked metal disks to build the magnetron instead. This meant they could be built in the thousands by machine operators and assemblers instead of a master machinist.

[@clytle374]

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.

[@norlockv]

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

[@shaider1982]

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

[@David-yo5ws]

@@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. 🤒

[@mytube001]

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

[@MrRandomcommentguy]

according to KZbin every device from WW2 won it

[@Leon-lt5gv]

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 🤔

[@playstation8779]

Well time to fit a radar on my jet bike. I guess I'll just tear open an old microwave and build one.

[@lucabrazi3067]

“The atomic bomb ended the war but Radar won the war”

[@pauljenks4901]

I'm pleased to see Sir Mark Oliphant get a mention. He was the quiet Aussie who always got on with things pushing for more to be done.

[@richardvernon317]

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???.

[@rickh3714]

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

[@Skipper.17]

Another unrecognised Australian.

[@johnwatters6922]

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

[@paulthomas-hh2kv]

Wish people would listen to interview with Mark Oliphant

[@dwaynezilla]

I imagine the creators would go something like "Magnetrons!! There's literally a billion of these in use in the future" > "Oh no the war didn't go well?!?" "Oh no it went really well. They are used in the kitchen." > "WHY DO PEOPLE NEED TO RANGE FIND LARGE METAL OBJECTS IN THEIR KITCHEN?!"

[@trukomf1nn162]

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

[@ibrahimcehajic]

They had an entire war just find out how to make a microwave

[@francisboyle1739]

Trust an American to invent microwave popcorn before the microwave oven.

[@richardkammerer2814]

Back in 1973, I failed in my attempt to dissuade a manager from heating a tin of soup in a full sized microwave oven. Observing from 10’ away, I saw a most surprising sight - a lovely noise and a nearly unhinged door. Not altogether a peaceful application. Another excellent video, by the way.

[@David-yo5ws]

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

[@musicbruv]

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

[@Nighthawke70]

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

[@abaddon1371]

@@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

[@20chocsaday]

Well, it was '73.

[@corporalpunishment1133]

It melted his chocolate bar! What happened to his nuts?

[@KD2HJP]

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

[@alainarchambault2331]

"The Cavity Magnetron," sounds like the kind of thing a UFO's alien would probe your butt with.

[@RamZar50]

3 key WWII technologies were related: Radar, Cavity Magnetron & Proximity Fuse.

[@mikedrop4421]

I love how there is no end to "the ____ that won WWII" video possibilities. They always end up being fascinating. They pretty much let the world's engineers go buck wild for a whole decade.

[@dr4d1s]

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.

[@paulmichaelfreedman8334]

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

[@PsRohrbaugh]

The relevance is important.

[@slugface322]

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

[@finonevado8891]

@@slugface322 we all know it's AI already

[@sojolly]

I worked with a British Engineer that worked on the magnetron. I met him at the end of his career in the 80s. He was proud of what they had accomplished.

[@SunBear69420]

Was he cute?

[@sojolly]

@@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.

[@sojolly]

@@SunBear69420 no

[@hydrolifetech7911]

As he should!

[@MBKill3rCat]

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.

[@TheFistytheCLown]

Wish I had known to ... microwave some popcorn before watching this.

[@zachmiller9175]

I want to know who convinced Doenitz that a 2000lb cow can't stomp on a mole hard enough to kill it...

[@gyyv]

I worked with an old WW2 radar tech, many years ago. He told me that when they brought it over, it blew his mind as to what that thing could do. Very interesting fellow to talk to. Passed away some years ago.

[@randywatson8347]

Brittain will always be remembered for inventing radar systems.

[@Ziggerzzz]

Nord VPN spoils all my favourite youtube channels

[@Andrew-rc3vh]

One of the first books I ever got into reading was a huge book published in the early 50s called Principles of Radar. This was the bible of radar technology from that era. My father used to work in the military designing this kind of thing. It was full of calculus. Fortunately I found a second book in the loft on calculus, so realised I needed to learn that first. I knew what a klystron and a magnetron was at the age of 12!

[@johncasteel1780]

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

[@finddeniro]

Fort Bliss ?

[@Andrew-rc3vh]

@@finddeniro Ultra Electronics in London

[@JesseP.Watson]

...I'm left wondering if the guys working on the magnetrons were cooking themselves then... which is not ideal.

[@rartu]

You know how difficult it is to find info on radar on the internet?

[@HitLeftistsWithHammers]

2:45 “ even though we left it years ago. “ Solid mention. 😂

[@cyonemitsu]

Great video! It should be noted that after the war, Yoji Ito, who co-developed a 8 segment 30cm cavity magnetron in Japan back in 1938, and then a 24 segment 10cm cavity magnetron in 1939, was shocked when saw the Birmingham magnetron in a museum in the UK as it had a shocking resemblance to his own design, in a fascinating case of convergent design.

[@williamzk9083]

-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. .

[@mikekelly5869]

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

[@iain8837]

I change magnetrons fairly frequently. They are used for producing microwaves inside Semiconductor Ashing machines where silicon wafers are cleaned using a basic O2/N2 microwave plasma. This is usually part of the Dry Etch process. This is however only cleaning. More aggressive etch processes use other gasses and RF generators to produce the plasmas. This microwave plasma is typically pink in colour. It’s actually quite a hard plasma to ignite ( hence when the magnatron isn’t working 100%, it needs replaced.)

[@davidtatum8682]

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

[@manishsakariya4595]

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

[@davidtatum8682]

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

[@pfadiva]

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

[@variabletalisman9765]

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.

[@kangirigungi]

How cool is it to say "I cook my food with radar"?

[@timothyirwin8974]

The Raytheon scientist should have taken a patent out on micro wave popcorn as well.

[@cernejr]

Magnetrons are also used to generate x-rays to treat cancer. The gold standard is klystron, but magnetrons are also widely used due to their smaller size.

[@jamallabarge2665]

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

[@cernejr]

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

[@paulmichaelfreedman8334]

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

[@MickHealey]

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.

[@MickHealey]

Great video here for anyone that is interested. I used to work on these machines. kzbin.info/www/bejne/oITKn4qcl6qrZ6M

[@TBrady]

We still use magnetrons and klystrons today on certain ghz communication equipment. One example is the an/trc-170 used by the Marine Corps.

[@David-yo5ws]

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.

[@flagmichael]

I knew my father was a radar tech in WW2, but he had a Marine with a .45 assigned to him to ensure the secrets would not fall into enemy hands. At least once a week the Marine would call "Drop!" (or Down, or whatever it was). My father would fall to his knees and the Marine would bring the .45 to the base of his skull. When especially drunk, he related how he had spent about ten minutes in that position as a skirmish raged on the other side of the wall. Anyway, radar was just secret, not _that_ secret, in those days. Declassified documents my brother dug up indicated he was a specialist in ranging radar for shipboard guns. The ship would fire the usual ranging round, but the radar could give much more precise correction information than optical observers could. That meant a crucial time advantage in any engagement: one correction and fire for effect. Why so secret? The radar returns from shells at those ranges required high power at very short wavelengths: that is what magnetrons do.

[@heikos4264]

3 years ago you told us that the Merlin engine won the war 😉

[@FIREBRAND38]

Whoa, pump the brakes there, Chief. Let's say that it _helped_ win the war.

[@therealzilch]

In the sixties, my brother and I played around with war surplus magnetrons. He went on to designing and building electronic control devices. I went on to designing and building musical instruments. Whatever. Fascinating history, physics, and technology. Thanks again from cloudy Vienna, where lunch is always on me if you're in town, Scott

[@philiptownsend4026]

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.

[@Chad-Giga.]

Do you both have cataracts now?

[@therealzilch]

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

[@philrabe910]

I used my magnetron to heat up my coffee water this morning!

[@Channelscruf]

We had the first Amanda radar Range model.

[@Allan_son]

Actually the random phase of magnetrons is a feature. In a sense it tags each pulse with extra information. Some klystron weather radars introduce quasi random phases to emulate this "flaw".

[@ianmangham4570]

King 🤴 klystron 🙏

[@Stoney3K]

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

[@atcengineering]

FM lonlinear modulation.

[@ShadeRaven222]

What won the war was the first computers.

[@ThrawnFett123]

I see this guy every few years, he presents impressive informative videos that make me deep dive information I thought I already knew about. 10/10. I look forward to seeing you in like 3 years again mate

[@user-lv5ij3zn9w]

Not all Chain Home radar masts were constructed of steel.

[@davidmarkwort9711]

When was the first magnetron invented? Cavity magnetron - Wikipedia In 1910 Hans Gerdien (1877-1951) of the Siemens Corporation invented a magnetron. In 1912, Swiss physicist Heinrich Greinacher was looking for new ways to calculate the electron mass. Need I say more?

[@SeanBZA]

Factoid about that early British research is that they needed to dump all that microwave energy during testing, and did not want to radiate it out. So they buried a lossy coaxial cable into a nearby salt marsh, where the late night testing caused unusual heating of the salt marsh, and a fog bank that was only over the dummy load area.

[@SunBear69420]

Lol you said load

[@vincentsutter1071]

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.

[@ProfSimonHolland]

thats interesting

[@SunBear69420]

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

[@ProfSimonHolland]

@@SunBear69420 quite revealing

[@GrinderCB]

Very interesting video, Paul. Always fun to learn about the components and tech that give us the conveniences we enjoy. Nice shirt, too. Hope the cancer recovery is going well.

[@snapfinger1]

Radar, the Norden Bomb Site & cracking the Enigma Code were decisive in Europe.

[@MrJackHackney]

I remember seeing the TV ads for the Radar Ranges!

[@Andrew-ep4kw]

I worked in satellite communications in the 90's and an interesting aspect of the klystron tubes is they were tunable. The resonant cavities that sat along side the electron beam had small plungers connected to screw mechanisms. This allowed the plungers to be moved and change the size (and therefore the resonance) of the cavities. We had a procedure to change the tune of a klystron; first we would unlock the tuning mechanism, then change the tuning, then re-lock the mechanism.

[@johncasteel1780]

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.

[@riverbender9898]

Part of my work in USAF was tuning kystrons on our transmitters, as needed..

[@NewtonInDaHouseYo]

Don’t we all hate those VPN ads by now? Raytheon would have been a great sponsor ;-)

[@JnnyUtah35]

Can sink U-Boats and cook me a hot pocket???? That’s like the greatest invention ever!

[@plunder1956]

There are several interesting strands of this story that could be expanded into more detail. The early development in several countries was most interesting. So was the sea-going anti-submarine war with a host of other technological tools & weapons. Then the H2S development path & policy for it's use. Some remember "The Secret War" series, with the battle of the beams etc. I'd love to see more done with these subjects. People I used to travel with every day in the 70s & 80s had been fighting in WW2 in tanks & aircraft. They wanted to read all about the technology that saved Britain when they were young. But most was still secret. I wish they had known then what I know now, but most are long gone.

[@tinto278]

"The Secret War" 😍😍

[@RCAvhstape]

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 KZbin takes them down.

[@tinto278]

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

[@msimon6808]

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

[@mbazzy123]

Great video Paul I always look forward to your new material.

[@ProfSimonHolland]

really the brits did not invent the cavity magnetron.. they improved an Ukrainian cavity device and the real work was done in Wembley by GEC who had innovative magnets, a special glue to seal the vacuum chamber and the help of the french, who had discovered a plating method to increase the life of the units.....but i guess i need to make a film about this hidden history. paul is totally correct in saying it won world war 2 . great subject.

[@HaysClark]

It's interesting to learn about an invention that was consumerized when so many inventions seem to go the other way and end up being militarized.

[@Spirit532]

The candy bar story is bogus, because if there was enough energy to melt the candy bar while he was working on/walking near the transmitter, there would most certainly and unavoidably be enough energy to very quickly and quite permanently cook the eyes, *and* make him jump from large area superheating of tissue(not-quite-burns) before the huge thermal mass of the candy bar would allow it to melt. It's probably just the heat of it being in his pocket that did that. This is also mostly why modern home microwave ovens have interlocks and shielding - their primary function is to prevent you from blinding yourself, followed by avoiding subsurface burns, and only in the last priority to avoid radio interference.

[@kwestionariusz1]

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

[@Spirit532]

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

[@robertmatch6550]

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.

[@virt1one]

Great video! I'm a radio enthusiast and I thought I knew most of the history behind the magnetron, but you managed to fill in a few gaps I didn't know I had.

[@joabarrera]

Nice to see the old MIT rad pictures, I was one of the last tenants of the famous E20

[@LeonAust]

British, I would throw the Aussies in this too. His name is physicist Mark Oliphant, he had a most amazing life with his involvement in the Cavity Magnetron and Atomic bomb, he was one of the physicist who flew to the USA with the Tizard mission that gave the cavity magnetron and atomic bomb information to the USA.

[@malthehansen7915]

What an absolutely fantastic video. As per usual, this channel has stoked my curiosity, and made me more appreciative of the conveniences that surround me. Keep it up!!

[@stagggerlee]

I bought my first microwave in 1975, an Amana Radar Range. I still have it in storage. I may have to dig it out and see if it still works. It weighs about 3 times as much as the one i bought last year for the kitchen rework. Cost $425 on sale back then, I don't know how I afforded it. Another great video!

[@David-yo5ws]

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.

[@Martindyna]

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.

[@henrysquillante9766]

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

[@jesse75]

Does it have one large dial on it ?

[@mycosys]

Did you just call Mark Oliphant British??? Cos lemme tell you a LOT of Australians gonna want a word.

[@ariefbudi427]

Stop playing around man, we only want to see the nuke

[@ThePhilosophyOfNature]

Very interesting and very well done, as always, thank You Paul.

[@kh40yr]

One of the first luxury use of the Microwave oven in the USA was in passenger trains. Thanks Paul.

[@randal_gibbons]

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

[@philipadams5386]

I believe that the Germans, who themselves had developed an early radar system, originally concluded that the British masts could not be radar masts, as they transmitted at a wavelength that the Germans believed was unsuitable for radar.

[@MattH-wg7ou]

9.7cm wavelength is about 3.1gHz for anyone wondering the frequency.

[@02markcal]

I love how this video ends with the technology used in something we can all relate to and use every day, showing just how much impact it had.

[@randal_gibbons]

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

[@alanmcentee9457]

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

[@philgiglio7922]

The cavity magnetron wasn't the only high tech the Tizzard mission brought to the US...penicillin mold was also brought over and given to Eli Lilly and Smith Kline and French. Within 2 years they had developed methods to grow and purify the drug in bulk...saving many lives MIT wasn't the only radiation lab set up. Georgia Tech set one up as well. It was still operational in 1968 when I started school there.

[@UninstallingWindows]

I think that the guy whose chocolate bar melted in his pocket should haven noticed that things are getting hot around the magnetron :D I mean, if you can hold a bag of popcorn in front of it, id expect your hand to go pop, along with the popcorn.

[@TehMagilla]

Peaceful purpose? Have you ever seen Gordon Ramsay discover a microwave in a restaurant kitchen?

[@970357ers]

Never ceases to amaze how much of our modern world was created during/because of WW2.

[@marklewus5468]

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

[@970357ers]

@@marklewus5468You sound like fun!

[@Bomkz]

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/

[@vincentsutter1071]

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

[@harrymills2770]

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.

[@AnitaJobby]

Welcome back, mate. 👋 Love your channel. 🙏🏻

[@theBlankScroll]

The Turbo Encabulator

[@tvtothepoint]

So WWII was won by the microwave oven?

[@RobbieCec]

The content and production as always are 1st class 🙂

[@Scoutter]

The more impressive usage of microwaves is done in a company near me. They build microwave-based Mining equipment to break down ores without the need of chemicals. Needs a lot of power though. Something between 50 kW up to 20 MW depending on the rig. They once said the biggest one they had build was powerful enough to increase the temperature of the water supply line of the city by 80 degrees in 1,5 seconds. So you put cold water in and only like 1 step further you had the same stream but boiling. Thats impressive.

[@terrylandess6072]

I remember 'Radar Range'. Now I understand why.

[@richardconway6425]

Wow! That was interesting ... so many things I didn't know in this story. Paul, do you think you could do a video on the history and development of *torpedoes* ? I have always found them fascinating, but have never entirely understood how they worked, especially ww2 era devices. Thank you!!

[@sixtorodriguez1902]

you never disappoint, glad you are still healthy after the recent scare.

[@MarvinHartmann452]

Many radio transmitter still uses valves.

[@ArjayMartin]

Plus 'Big Wing' trick

[@coniccinoc]

Love the WW2 content! ❤ Thank you

[@richardvernon317]

One thing that people don't mention is the Cathode design in the GEC Magnetron wasn't designed by them, it was French!!! One of the French electronics research labs near Paris shared the design of that cathode with GEC in May 1940, just before the Germans Invaded. What it did do was massively extend the running life of the device and allow very high power, especially when GEC discovered that to stop the cathode from burning out, as soon as you had the magnetron run up, you had to turn the heating element off, as a sizable amount of electrons were being thrown back into the Cathode by the magnetic field and they caused it to heat up,

[@ProfSimonHolland]

yes....this is a fascinating story

[@bwarre2884]

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.

[@malcolmlewis5860]

It's inventor, Oliphant said the Manhatten scientists may have won the war, but the cavity magnetron made sure we did not loose it in the battle of the Atlantic.

[@lordgarion514]

Its a good thing that chocolate bar wasn't wrapped in a foil lined wrapper.

[@johnannan2506]

I never mind waiting as long as it takes for the next Curious Droid video to be made. They’re always great stories, well researched, well written and clearly presented for people who know a bit of science. Thank you. Your hard work is very much appreciated.

[@MichaelKunz-mt2oo]

Wonderful video, thank you for posting. Not only did Bell Labs copy the magnetron and begin production, within 1 week of receiving that first cavity magnetron, Bell engineers boosted its power about tenfold. Robert Buderi has documented much of this arcane technological history a great book "Radar:The Invention That Changed the World" which is now in paperback.

[@dosmastrify]

The engineer guy also has a great vid on this

[@billfargo9616]

The Norden bombsight vastly improved the accuracy of bombing runs in WW2.

[@Mtmonaghan]

Not it did not, it was a huge failure.

[@andrewremobs9854]

I sometimes think that it's sad that nearly all of humanity's technological leaps come about due to conflict or war of some type.

[@leehotspur9679]

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

[@holy3979]

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.

[@ChucksSEADnDEAD]

​@@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.

[@toxlaximus3297]

Most people don't know what a magnetron is but they know every piece of dirt on every celebrity, that ain't right.

[@jayg1438]

and now it makes popcorn

[@GereDJ2]

Sometimes called a Klystron tube, it basically does the same thing, just in a slightly different way.

[@Sir_Uncle_Ned]

It really is amazing just how important technology was to winning WWII

[@killman369547]

Technology and industrial capacity. Two of the arguably most important elements to winning any war. There does come a point where one's technological and industrial edge over an opponent become so great that losing is simply impossible, unless extreme amounts of incompetence and downright treachery are involved.

[@Machia52612]

@@killman369547 Do young Americans have the will to fight? Without that, no technology or industrial might can make up for that.

[@slartybarfastb3648]

Like the space program, defense spending has led to many more scientific advances useful to consumers and doctors than would otherwise have been even remotely possible.

[@normannabatar6260]

It was pure luck that Goering missed the significance of the radar. His incompetence cost him the Battle of Britain. On the other hand, the British kept this secret such that nobody knew how potent it was.

[@DeFineAl]

I did a video biography of an RSRE scientist who mentioned that his boss accidentally left the prototype in a phone booth during the war, fortunately when he realised and went back it was still there!!