CORRECTION: I implied that the superheterodyne system used signal *addition* like playing two guitar strings at the same time, but I have been corrected and it is a signal multiplication not addition. Sorry for the confusion.
@davidhaworth18022 жыл бұрын
In a sense you are also correct in that the envelope of the combined guitar string output contains the difference frequency. However, in practice, schemes that produce multiplication and suppress the local oscillator are preferred. Great channel BTW.
@raymundhofmann76612 жыл бұрын
"Mixer" is a unlucky name, as it implies addition. On the other side if it has a non linear transfer function, which at some point nearly everything has, it creates the new frequencies of multiplication and more. Mixer is just a sloppy name coined in the beginning of a non linear amplifier stage "mixing" the local oscillator and the rf input.
@raymundhofmann76612 жыл бұрын
@@davidhaworth1802 The "beat frequency" effect is a illusion due to the finite time interval our ear and brain analyzes the spectrum with, it perceives two close frequencies as one modulated frequency. Our ear and brain in effect is a non linear frequency analyzer, similar to what you get with the magnitude value of a frequecy spectrum from a discrete fourier transform of a time interval. Taking the magnitude of a complex frequeny bin is the non linear function similar to the ear where certain nerves detect vibration strength of tuned vibrating hairs.
@richardcallahan86982 жыл бұрын
Sum and difference resultants of algebraic combination, like a piano makes beats. You are correct.
@rayoflight622 жыл бұрын
When you beat two frequencies F1 and F2 in a mixer (non-linear component like a diode or a triode), you obtain two more frequencies, F1+F2 and F1-F2. The IF stages (usually two or three of them) do filter out the F1+F2 component, while the F1-F2 corresponds to the IF frequency of the radio, and is successively amplified and detected.
@proudsnowtiger6 жыл бұрын
Armstrong deserves a Hollywood biopic... tragic tech hero of the 20th century.
@Kathy_Loves_Physics6 жыл бұрын
proudsnowtiger he sooooo does. I would pay big bucks for that.
@proudsnowtiger6 жыл бұрын
Biting my tongue over the FM/Sarnoff story to come - no spoilers! But love that you're covering the commercial shenanigans as much as the technology. Anyone who thinks today's IP wars are something new knows nothing about Marconi, de Forest, Sarnoff et al. Oh, that great shot of Edwin and Marion on the beach with the first portable superhet - I didn't know until just now that it still exists and is in the Henry Ford museum. kzbin.info/www/bejne/hoC0pKmJisRld9U
@Kathy_Loves_Physics6 жыл бұрын
proudsnowtiger It’s certainly changes your view of Sarnoff’s complaint when Armstrong climbed to the top of the tower doesn’t it?
@dahawk85745 жыл бұрын
Lee de Forest got a nice tribute with Dr McCoy of Star Trek fame. Credit to his parents, considering that baby Kelly was born in 1920. And you can say that Armstrong got his tribute in space as well, considering how the first to land on the Moon were EDWIN Aldrin & Neil ARMSTRONG. The tie actually runs deeper, because one year prior to the historic mission, Aldrin's mother committed suicide. Her family name was Moon. Her father, another Moon, also ended his own life. Now while a lot of current attention has been given to Neil Armstrong in recent months, this is not the first movie made about that mission. Back in the 70s, a movie was made about Buzz called Return To Earth, with Cliff Robertson playing the lead. Aldrin's depression ran deep and he too came close to ending his own life. Now we have excellent movies made about people like Steve Jobs. It would be great if today's generation got to learn about the tech heroes of yesteryear. A movie about Sarnoff, de Forest & Armstrong. I agree that would be excellent. De Forest has a star on the Hollywood Walk of Fame. Howard Armstrong deserves far more recognition. Ask someone who invented radio. If they have a guess, they might say Marconi. But his invention was nothing like the radio that revolutionized the world. That happened because of de Forest's vacuum tubes and Armstrong's receiver. THESE deserve to be household names. THANK YOU Kathy, for such an excellent video!
@anthonyarmstrong47012 жыл бұрын
Another Armstrong inventor What about the one who invented the system that most deep oil platforms use
@zubershaikh7663 Жыл бұрын
The knowledge u spreading is priceless.. very nice .. i am watching u from india 🇮🇳
@ebayscopeman Жыл бұрын
One of the great things about the superheterodyne that makes the design so great is the concept of the IF amplifier. It is the design of the IF amplifier that makes these designs so sensitive and work so well. The main reason: it is easier to make a high gain, lower noise amplifier using several narrowband cascaded sections than trying to make a single stage wideband amplifer as used in prior tuned RF designs. Howard Armstrong was a true genius and his principle of the superheterodyne method used in the 1920's are still widely used today in receivers and test and measurement equipment to this day. It is sad that he passed in the way that he did, and it seems that few people even know anything about this great man. As a side note I read the book I got from you at PCB Carolina last year. I could hardly put it down. I am looking forward to your next one!
@atomicdmt87632 жыл бұрын
LOVE these 10min clip- format!
@NemonicanatLarge2 жыл бұрын
I have to admit, your videos are amazing. First time I noticed, that your videos were probably boring and probably not worth my time but I decided to check one out. For the most part I thought that they were worth m my time so I started watching. This one was awesome. The research and presentation I was impressed. I started my career in electronics and computers. Now, after over 50 years (I'm 68) in these fields, even tho I managed to hamstring my future.I've managed to talk my way into some fantastic jobs. These included DEC, Compac, and others, I feel I have, in many ways, succeeded . It all started with repairing a radio that had been thru a fire. I was 14 and I was hooked. Seeing the true history of RCA, I am beyond impressed. Thank you.
@acmefixer12 жыл бұрын
Thanks for giving viewers the real, often sad history of radio. Sarnoff did eventually get to be a General. But he was a mean guy. Most AM radios used a local oscillator frequency that was above the station's frequency, so the IF was the *difference* between the station frequency and the local oscillator frequency.
@flagmichael2 жыл бұрын
If it were on the low side, the oscillator in AM radios would have gone below 100 kc! (Hey - we are talking about history; we didn't have any stinkin' kHz in those days!)
@Steve-GM0HUU2 жыл бұрын
@@flagmichael Yes, back in the day it was kay-sees and em-sees.
@jamesmulcare53212 жыл бұрын
Sarnoff never served a day in the military. He was given a Brigadier General rank because of his work on General Eisenhower's communications staff. He stole basically stole Farnsworth's television patents and screwed him out of a 1 million dollar infringement judgement by never paying it. He was more than mean, he was a ruthless scumbag...hope it's nice and hot where he is now
@bobblacka918 Жыл бұрын
Love your channel. There is nothing quite like it for drama and accuracy.
@иванепифан-к8ж6 жыл бұрын
What is especially wonderful is that the principle of superheterodyne reception invented by Edwin Armstrong is the basis for the operation of all transceiver devices today ! Long life great," the right " invention ! (and of course , even Mr. Edwin is the inventor of regenerative radio and FM radio) I certainly do not know English, but many words from radio engineering I understand. There are very few videos on KZbin about this great inventor , and you have new precious historical photos. That's great ! It's terribly interesting ! Thank you ! 73 !
@Kathy_Loves_Physics6 жыл бұрын
I'm so glad you enjoyed it.
@brianharrison10512 күн бұрын
WOW!!! This is a must-watch video for anyone interested in early radio... Fabulous research and delivery! WELL DONE!!! I'm subscribing!!!!!
@mariofilippi35399 ай бұрын
I enjoyed you video very much, thanks. Sarnoff was the proverbial guy who pulled himself up by his own bootstraps.
@jonkzak2 жыл бұрын
What a wonderful professor you must be. Your definition of AM radio finally penetrated my thick skull and the Light bulb of understand blinded me. Oh how I wish I had heard this in my youth. Thank you for the wonderful video. Be safe and keep sharing.
@kennynickell98832 жыл бұрын
No questions, just CUDOS for great vids..
@CharlesAustin2 жыл бұрын
We take radio for granted: not now ..!! Love the history you give !!
@josephstratti522 жыл бұрын
This is the most interesting series on KZbin that I have ever come across.My utmost praise for Kathy and her content.Just fantastic and enlightening!
@Kathy_Loves_Physics2 жыл бұрын
Aww thanks
@tomstrum62592 жыл бұрын
Hi Kathy !! ....You should stand with your original "Uncorrected" Beat frequency signal conversion explanation illustration....Anyone familiar with reading U. S. patents, will frequently encounter inventor applicant claims so repeatedly "micro-detailed" exaggerated to point of functional fantasy !! But yet, in Armstrong's 1920 original Patent # 1,342,885 ... No mention of voodoo,, Algebraic--Trigonometric, "Multiplication" signal conversion is found.... Just the simple but new (for 1918) radio "Reception" application principle of Beat frequency conversion to "Lower" frequency Amplification stages... Your original 1920 radio vintage "Invention Breakthrough" style explanation is most appreciated !!! Keep your great informative content coming & forget the techno nitpickers !! .....
@erin190302 жыл бұрын
We had a big party in1970 when Sarnoff retired. However we didn’t invite him. He was a real Party pooper.
@bobwferguson2 жыл бұрын
I got a degree in mass communication and I’ve seen your videos for the past week and learned more from them than college
@ralphburns66594 жыл бұрын
HEY MR. ARMSTRONG THANK YOU FOR ALL YOUR GREAT INVENTIONS MY FRIEND!
@Kathy_Loves_Physics4 жыл бұрын
Definitely, love Armstrong
@7c3c72602f7054696b4 жыл бұрын
Thank you Major Armstrong, and thanks for the video!
@ocpud29993 жыл бұрын
I consider Armstrong as one of my childhood heros. My dad was an engineer. And saw how his inventions changed the world. It's sad he is not known more
@Raymond_duck Жыл бұрын
Brilliant!!! Absolutely loving these videos.
@garbo89622 жыл бұрын
Believed the old superheterodynes only used 5 tubes. A 35W12 rectifier tube, 50C5, 12AU6 and 2 others. Learned about them back in the 1960's. Have an old tube radio in my garage that I still use. Interesting vid. Ashamed very few young kids get interested in electronics or turning wrenches. Learned how to solder and use my dads model 260 Simpson meter before I learned how to drive. Put together a radio, tube & transistor tester, and 25" Heath kit color TV.
@flagmichael2 жыл бұрын
The "All-American Five" came in two versions: one with octal base tubes and one with miniature tubes. Those were the miniature tubes. I think RCA had the original patent but when that expired everybody made them virtually the same. For years the RCA tube manual had a schematic of that version in the back. I believe transistors displaced even those tubes when transistors became cheaper than tube sockets. The miniature tube radios came on printed circuit boards near the end but the economics just shifted too far too fast. RIP to the AA5. In this history channel, I would be negligent if I didn't mention that the book, "SONET/SDH Demystified" has a few pages about the birth of the transistor. In short, the post-WW2 boom brought high expectations, including private instead of party telephone lines. That required more copper, which was being snarfed up by the housing boom. The solution was multiplexing, but vacuum tubes had heat and energy problems. That is why the transistor came out of Bell Labs.
@johnstone76972 жыл бұрын
The AA5 lineup was 12BE6 mixer, 12BA6 IF. 12AV6 detector/af amp 50C5 audio output and 35W4 rectifier.
@8546Ken2 жыл бұрын
You're referring to the small "AC-DC" table radios. The large console radios may have had more tubes and a power transformer. With a transformer, all the tubes had 6.3V heaters The tube numbers were often just 2 digits. They usually had shortwave bands.
@PabSungenis2 жыл бұрын
I’m a broadcaster, so Armstrong has always been my hero.
@johngough29582 жыл бұрын
Great story - have to keep watching!
@jamespowell14425 жыл бұрын
This is a great channel,keep up the good work!!
@Kathy_Loves_Physics5 жыл бұрын
So glad you liked it.
@giovafra612 жыл бұрын
I've just discovered your channel and so I have to congratulate with you. I'm watching the series dedicated to the radio, from the 1st valve, Fleming, De Forest, Armstrong and so on. Very clear explanations. That's a good way to learn. Thank you and...GO AHEAD IN THIS WAY!
@Kathy_Loves_Physics2 жыл бұрын
So glad you liked it.
@sammyk70242 жыл бұрын
This video brings me back wonderful memories, as my very first "serious" electronics project was indeed a superheterodyne radio receiver, some 40 years ago. It was a helluva lot of fun, as I had my siblings, my mother and my grandpa help me build a ridiculously huge dipole antenna to test the dang thing.
@goodmaro2 жыл бұрын
A Beveridge?
@sammyk70242 жыл бұрын
@@goodmaro it ended up as a Beverage, indeed. a half wave one, although my original plan was to set up an actual full wave dipole. details are fuzzy, but I'd guess I ran out of copper wire.
@anguscampbell23025 жыл бұрын
Absolutely love your tuition. Right at my level . Less is more. Thankyou
@amramjose2 жыл бұрын
That was great! I have always been a fan of radio, specially vintage radio. Let's go to the rest of the FMstory!
@gregnewberry48132 жыл бұрын
Empire of the Air is a very interesting documentary of early radio. Nice video!
@Kathy_Loves_Physics2 жыл бұрын
Great book and documentary
@USNavySeabee5 жыл бұрын
My father worked along Edwing Armstrong until his death at the Alpine Tower in New Jersey.
@Kathy_Loves_Physics5 жыл бұрын
That is amazing. I hope I described Armstrong accurately. Did your dad have any personal stories about Armstrong? I would love to hear more. Feel free to email me (my email is in the about section but if I add it in my comment my comment gets flagged!)
@ralphburns66594 жыл бұрын
WOW, WHAT AN HONOR, JUST WOW!!!!
@grzesiek1x11 ай бұрын
based on Armstrong schematics I have just built a receiver, finally I got and understood how it works and what it is even more important how to make it work or adjust. principle is quite simple but there are a lot of things to consider and check...
@charlesharkin2165 Жыл бұрын
Lovely presentation
@jackbronsky2 жыл бұрын
Kathy, you are simply the greatest.
@robhtp38174 жыл бұрын
Okay I’ve seriously been binge watching your videos, today I’ve watched 8 of your very informative, educational, & entertaining videos. Thank you so much. I almost want to go out and invent something. 😆 or at least maybe buy a DIY radio kit to show my 9yr & 11yr old daughters how a radio works.
@Kathy_Loves_Physics4 жыл бұрын
RobHTP what a fantastic idea! to be honest I have never made a DIY radio and I so want to.
@microdesigns20002 жыл бұрын
Did you ever build a DIY radio? I built a crystal radio as a kid and TDA7000 radio as a teen. Nowadays I am an automation and controls engineer. I am thankful to my parents who purchased an electronics kit when I was young. So I hope you built a radio with your kids. 📻
@ronwisman17672 жыл бұрын
Just discovered your shows. Love this
@prabhakarv41933 ай бұрын
Very nice and informative. Thank you
@markrowland13662 жыл бұрын
Thankyou for this simple explanation of a wonderful gift to mankind. At twelve I won a Philips constructo set, on which I assembled a three transistor radio receiver, winning it as a prize. I was manager of the largest Neon sign shop in Australia and edited the new handbook on neon shop practice. We used 18 kV transformers at over one amp. kHz radio transmitters in creating plasma for desktop signs. When upward lightning was reported and it's colour described, I was able to introduce it's finders to Neon equipment pervayers, who produced the associated vacuum, and were observing the colours when testing product. I hope that confirmed what was maybe still conjecture.
@matt-g-recovers Жыл бұрын
These are great videos, thanks so much!! Subbed up also
@94870874962 жыл бұрын
Highly informative and motivating. Thank you.
@amtsgedicht2 жыл бұрын
thank you - you're the first person that makes me understand the superhet system and I tried many before!
@wakomatic54022 жыл бұрын
Great storytelling
@dysfunctional_vet2 жыл бұрын
i started working with radio seriously as a career in the 1970's. the vac tube R390's (surplus) WW2 radios were amazing for their versatility, you could close the band pass down to .1 hertz, meaning you could hear individual signals in sideband. I could listen to stations from south africa, china, russia, south america and other places all using a 330 foot dipole about 40 feet hung in trees. working with the two i had, was pure joy and the BFO made the un-intelligible crystal clear for listening. good program
@WarpFactor9992 жыл бұрын
Kathy, having been a ham for some 60 years, and working in radio, radar, general electronics, and computers since, I find your content wonderful! Well done! I too share a strong interest in the history of electronics. You could do segments on the early days of amateur radio, rotary spark gaps, coffin kilowatts, etc. The ARRL has some wonderful source material. Sadly, amateur radio is dying out as it's now simple to talk around the globe over the internet. But how many people know that many of the early radio improvements came from hams? Hams even had their own satellite in orbit as a radio and data repeater system.
@flagmichael2 жыл бұрын
Hey! I remember when disaster communications in the first minutes and hours was often through ham radio. (Former WA6TDG - I let my license lapse when I started working in avionics. One night I wondered, "who is paying me to do this?")
@WarpFactor9992 жыл бұрын
@@flagmichael LOL! Indeed. Hams did it as a service to the public and to justify their use of the ham radio bands. I've kept my ticket but am not active anymore. Not many of us left on the air anymore. The FCC has tried very hard to get more people interested in ham radio, but it is just fading away like us old farts.
@yahyaqarshaee97645 жыл бұрын
I am truly honored Kathy for meeting you 💜
@Kathy_Loves_Physics5 жыл бұрын
Why thank you. The honor is all mine.
@bombadeer82312 жыл бұрын
Love your channel Kathy 👍
@JamesWHurst2 жыл бұрын
A most stupendous telling - of a story rarely told. Thank you for creating and sharing this.
@Kathy_Loves_Physics2 жыл бұрын
Glad you liked it
@GrahamC-eg6ln Жыл бұрын
The AR-812 is a reflex design with the first vacuum tube being both the RF amplifier and the first IF amplifier. The very low intermediate frequency of 40 Khz is so that the RF and IF signals can be kept separate by simple filters.
@GrahamC-eg6ln Жыл бұрын
The low intermediate frequency would require the IF transformers to be quite bulky - but the cost saving of reducing the tube count would more than offset any increase in IF transformer manufacturing cost. Reducing the tube count would also extend battery life.
@josealphonso28482 жыл бұрын
Learn a lot more from you than my physics class
@dennisfahey2379 Жыл бұрын
I love the line "Think Fiddler on the Roof, but with a painter". That is absolutely priceless.
@joeretired45522 жыл бұрын
Great video. Great history.
@glenncurry30412 жыл бұрын
Please clarify that heterodyning only works in nonlinear systems. Typically band limited circuits. Our hearing is nonlinear which is why we can tune a guitar string that way. So are the circuits in heterodyne receivers.
@flagmichael2 жыл бұрын
Hopefully, only the mixer is non-linear in AM receivers.
@glenncurry30412 жыл бұрын
@@flagmichael Every tuned stage is band limited and thus nonlinear by definition. IF Coils between stages. But yes heterodyning only happens in the mixer. Hopefully!
@8546Ken2 жыл бұрын
If the front-end RF amplifier is non-linear, you get InterModulation (IM) interference due to heterodyning of several incoming signals. We try hard to keep the front end linear. but there will still be IM if the signals are strong enough.
@glenncurry30412 жыл бұрын
@@8546Ken All front-end RF amplifiers are non-linear. Otherwise it would require an infinite bandwidth from DC to light (and beyond?)
@curtvincent37283 жыл бұрын
OMG! You are amazing! That is the best description of the circuit on all of youtube! Well done! And you did a good job of putting Armstrong in the proper light. Sad ending.
@Kathy_Loves_Physics3 жыл бұрын
Thank you I’m so glad you liked it. And poor Armstrong, still makes me sad to think of it
@budokai67062 жыл бұрын
Very cool stuff! Thank you...
@Robinzano2 жыл бұрын
I used to live in Somerset, New Jersey, right down the street from Radio Court. About a mile away is Marconi Park. I've heard that Marconi Park is where his antenna was, and Radio Court is where the transmitter was. I'd love to see a video with the history of that, especially since I lived right around the corner, I'm an amateur radio operator, and my full time job is a radio communication specialist.
@AdamosDad2 жыл бұрын
The first receivers I worked on in the Navy, back in the 60's had BFO controls on the front panel.
@jeffharrison1090 Жыл бұрын
Another GREAT and all so interesting production! Are you surprised by the twist and turns that ppl lives take profes- sionally and personal for their success? Published are the great highlights, triumphs and accomplishments, but not the sometimes tragedies that later follows like here and in other tales like Vail and Morse with the telegraph? Friends splitting because of greed or wanted top billing. Others becoming depressed and sought isolation! Funny, how we tend to always have the happily ever after image in our minds...I like happily ever after....lol!!!
@steveperry13442 жыл бұрын
i really enjoyed your story of some of the history of radio. i was trained as a ground radio repairman when i was in the air force 50 yrs ago and worked on very large radio transmitters.
@AnbroBR4 жыл бұрын
Nice video, Kathy! I have read two books that covered the life of Armstrong - the first was written by Tom Lewis and the title was "Empire of the Air." It was the book on which PBS' home video, "Empire of the Air: The Men Who Made Radio" was based. The second book was written by Lawrence Lessing and its title was "Man of High Fidelity: Edwin Howard Armstrong." Having read both of those books and having watched PBS' video numerous times, it is my opinion that it was Sarnoff's ruthless quest for the almighty dollar that drove Armstrong to suicide. The worst part about it is that they were at one time very close friends. This coming December 18th (2020), and continuing on through December 20th, I am going to be using my ham radio station to operate a "special event" in honor of Armstrong's birth and his accomplishments. I will be primarily using the "20 meter" (14 MHz.) and the "40 meter" (7 MHz.) ham bands for my operation. I will also be checking out conditions on the "15 meter" (21 MHz.), the "80 meter" (3.5 MHz.) and the "160 meter" (1.8 MHz) bands. The bulk of the operation will be on the 20 meter and the 40 meter bands - the 20 meter band being a "day-time band" and the 40 meter band being a "night-time band." My special event operation will only use "CW" - ham radio jargon for Morse code. I am quite sure that I will be able to put a good signal into Europe, Asia and also "down under," in Australia and New Zealand. I plan on having a lot of fun in putting this on and it will be my way of expressing my appreciation to Armstrong, without whose inventions radio, television and cell phones would not be like they are today! 73, Brad Anbro, N9EN
@Kathy_Loves_Physics4 жыл бұрын
Brad, I also enjoyed both books very much (and, of course the PBS video was very well done). I love your idea to honor Armstrong and I like to think he would like it too. Cheers, Kathy
@Alkoluegenial6 жыл бұрын
Just wanted to say that I really enjoy your videos and have already recommended them to several people, who also love them. Have a nice day.
@Kathy_Loves_Physics6 жыл бұрын
Alkoluegenial thank you so much! You have made my day.
@richlaue Жыл бұрын
I understand how it works, and having built, from scratch, several radios, I understand what the advantages are. In addition, my grandfather had a, non superheterodyne radio that required the user to individually tune each stage of the receivers amplification. This radio also needed 3 batteries of different voltages
@karthick86c5 жыл бұрын
Good video Kathy dwelling into the history of superheterodyne and how it came to be what it is today. Keep up the good work and you are bound to get a large audience here on youtube in no time.
@Kathy_Loves_Physics5 жыл бұрын
Thanks so much! If you feel like sharing on social media that would be awesome. Cheers, Kathy
@karthick86c5 жыл бұрын
@@Kathy_Loves_Physics Sure Kathy. Will do. Thanks.
@dr.mikeybee2 жыл бұрын
You're such a great vlogger. I really love these.
@denvrital2 жыл бұрын
Hi Kathy... Love your program.. just found it by accident. I am now hooked. You are a very good commentator. I worked for RCA in their tube division in Avenel, New Jersey in my teens. I loved the energy in that factory. It was an interesting place to work. In my youth, I built many kits using tube technology such as EICO and Heathkits and I still have most of them today. My VTVM and RF oscillator still work after all these years too. Thanks again for the great story and I look forward to many more. Lenny from Denver
@Sam_on_YouTube2 жыл бұрын
I don't see a video yet on Hedy Lamarr, the actress who invented frequency hopping, the technology behind cell phones. That would make a great addition to your catalog.
@Kathy_Loves_Physics2 жыл бұрын
It’s coming, but it’ll take me a while to get there.
@davidatrakchi27072 жыл бұрын
You have an amazing way of presenting these facts
@marzymarrz51722 жыл бұрын
The Sarnoff Marconi connection is amazing. It’s as if the universe opened a door.
@johnpeterson72642 жыл бұрын
Great video for enthusiasts of radio !
@usmale49152 жыл бұрын
Great channel. You're the best. I like how you go into great detail...it's refreshing, to say the least! I thoroughly enjoyed this particular video. And I also just subscribed! Thank you for sharing, you are one very knowledgeable individual!
@rosswarren4362 жыл бұрын
Looking forward to your book! We need a cast of characters map...LOL...
@randydireen35662 жыл бұрын
Just found your channel! You deserve millions of subscribers. Very happy. I love this stuff.
@LaurenceRonayne2 жыл бұрын
Ok I'm hooked on your videos now.
@Kathy_Loves_Physics2 жыл бұрын
Bwa ha ha!
@cranegantry8682 жыл бұрын
Fascinating, loved this. Subbed too.
@titicoqui Жыл бұрын
of course impossible to resist video
@davidepperson23762 жыл бұрын
Great video and great explanations - thanks for sharing!
@TheEvertw2 жыл бұрын
The heterodyne design is one of the key breakthroughs of the century. It is amazingly elegant! The key technical benefit is that a highly optimized filter can be used to convert the intermediate frequency to audio. Without the heterodyne principle, this filter would need to be variable, making it much less optimized, resulting in far worse selectivity for the radio. This would have meant much more bandwith would have to be allocated for each radio station, and far worse audio quality. And it would have made it almost impossible to mix color information and audio in with TV signals: these are transmitted in tiny bits of bandwidth that require very selective filters to reconstruct. Later radio's combined the two variable capacitors into a single device where one knob changes both capacitors, so the antenna filter and the internal oscillator change frequency in harmony.
@flagmichael2 жыл бұрын
Ages ago I acquired a Bosch console radio made in 1928. It was a TRF (Tuned Radio Frequency) receiver with a 3 or 4 gang - I forget which - tuning capacitor and a tuning dial that ranged from 0-100. It actually worked fairly well for local stations - other than not having Automatic Gain Control - but not so much for distant stations.
@karlroebling33162 жыл бұрын
Wonderful!
@captainernest43072 жыл бұрын
You are amazing.
@ricsanders692 жыл бұрын
Fantastic video...I'm going to suggest to new Ham Radio Operators to watch your videos...these are very informative. I've built a few radio kits and a couple were Superheterodyne aka Superhet! 73 de KN4FTT
@georgekoerner65912 жыл бұрын
Great job
@davidkleinthefamousp Жыл бұрын
Ty Kathy I would even listen to you read the phone book!
@Kathy_Loves_Physics Жыл бұрын
Thank you, but I think I would do one of the worst renditions of reading the phone book ever considering that I mispronounce words so often. 🤣
@siyunguo81763 жыл бұрын
Thank you!
@lcmd78332 жыл бұрын
This information is fascinating! With a technical education and background, these are things I should know ... but I never was exposed to the historical knowledge, which puts everything in context.
@galaxysam13753 жыл бұрын
Very nice!
@PaulHigginbothamSr2 жыл бұрын
I really liked your gift of super heterodyning. What you do not mention is Armstrong in France and finding two radios in one room interfering with one another during Ww1. In your previous video of the vacuum tube I had no idea these people from the past didn't really understand how triode tubes work. I just assumed they knew from the get go it was electron flux not ions. So as usual it was an accident not a blazing certainty and here you show 3 knobs on these difficult to manage receiver dials. So the same position on the dial was always changing but you could mark the stations on two dials to reach the station you wanted.
@jackd.ripper76136 жыл бұрын
I'm privileged to be the first commenter. This is the single most entertaining channel to which I subscribe. The little throw-away bits of history are fascinating. 2:15 I didn't know he was a philanderer. That's just one of very many throughout this series. I really dig your stuff. Was that your husband on the guitar? I play several instruments (poorly) guitar among them and being a history buff, could you possibly talk about the development of the magnetic coil pickup at some point? Keep it up!
@Kathy_Loves_Physics6 жыл бұрын
Jack D. Ripper jack! So great to hear from my biggest (and possibly only) fan. Yes that was my hubby on the guitar. I used to play badly myself before I met him but then I was so intimidated by the 12 string guitar that I stopped. I really need to get back to my bad guitar playing. It was so fun I was thinking of writing a book on the Physics of Music someday but who knows when I will get around to it. Electric music is fascinating. Still, with all my irons in the fire i wouldn’t hold my breath. Cheers, Kathy
@victorpinasarnault79102 жыл бұрын
Wow... what a history! Why Hollywood didn't explored that?
@MISSIONCAT112 жыл бұрын
When I was in school, one very interesting xperiment I was required to perform was to measure the mass of the electron. This was not done directly, rather by observing microscope bubbles moving in the air under an electric field, and then computing the "smallest common denominator" of the oil droplets velocity.
@flagmichael2 жыл бұрын
The famous Millikan oil drop experiment. If not for that experiment we would not have the concept of wave/particle duality... electrons would only be known as waves and the atomic model would be radically different.
@jmguevarajordan2 жыл бұрын
You went to a very nice high School, I only saw that experiment in the textbook.
@qkitselectronics54152 жыл бұрын
Great video. this should have many more likes, come on people show some love for all the research and great pictures Kathy has put together. Have a great day everyone, if you can't play a sport, be one.
@alexhu79392 жыл бұрын
love your energy and concise lectures! Unless I am hearing it wrong, the B-frequency, or IF, is generally 450 KHz, not 45KHz. Usually, for example, if the antenna circuit is tuned to 1,000 KHz, the local oscillator is tuned to 1,450KHz.
@michaelmiller6412 жыл бұрын
They sometimes use an if as low as 50khz, for improved selectivity, although that tends to be in double conversion receivers
@Observ45er2 жыл бұрын
Alex Hu, There have been variations of this "common" IF frequency over time in the 400 kHz range, as well as varying all over the place for all kinds of different receivers. .. P.S. The term is "beat frequency".
@flagmichael2 жыл бұрын
455 kHz was the standard by the time I got involved in the early 1960s. I never saw an AM broadcast band radio that used a different frequency, and I saw a bunch of them in the mid-20th century.
@michaelmiller6412 жыл бұрын
@@flagmichael but amateur ham band radios used all sorts of if frequencies, 1.6 MHz, 100 khz 50 khz double conversion
@johnstone76972 жыл бұрын
The standard for single conversion AM radios in the US was 455 kHz. The European sets used 460 kHz. Car radios generally used 262 kHz.
@0dbm2 жыл бұрын
Thank you , I Learned so much , I am hooked
@ohgosh58922 жыл бұрын
Modern radios are now all DSP, but superhets were king for scores of decades.
@flagmichael2 жыл бұрын
There is a mix of them. Our digital microwave (before retirement) was made by Alcatel until about 2015, The high bandwidth series (the MDR4000s) were superhet with an IF somewhere around 60 MHz, while the lower bandwidth MDR-6000s were direct conversion.
@keacoq2 жыл бұрын
Just so interesting, thank you
@BernardS4 Жыл бұрын
great job you have put this history together. There is part of the RCA story that I have read or heard about. didnt the Navy have a part in founding RCA out of the American arm of Maconi with partnership with Westinghouse, GE. United Fruit
@charlesmrader2 жыл бұрын
This video is quite personal to me, because of my family history. My father, Abraham L. Rader, was born in 1906, of immigrant parents, and when he was a teenager, he was interested in radio. In those days, radio for ordinary people was a crystal set, with all the problems of amplification and tuning that this video makes clear. But my father started a company to make and sell crystal radios. He also hired an engineer to try to solve some of those deficiencies. My father had no formal training in electronics, just hand-on experience. His engineer was a perfect fit, very bright but not entrepreneurial. That engineer invented the superheterodyne radio. My dad's company sold the first superheterodyne radios to ever reach the consumer market. Sadly, from our point of view, Sarnoff and RCA had the necessary patents and my father, who didn't even know what a patent was, found that he had to leave his business or be sued. He never talked to me about that part of his life, but of course my mother knew about it. When he died, I put together an obituary speech and that was when I learned about it.
@carllafrance55102 жыл бұрын
Excellent video just found your channel d subscribed !
@russbellew63783 жыл бұрын
Excellent and accurate presentation.
@Kathy_Loves_Physics3 жыл бұрын
Thank you I try my best
@smiggo14812 жыл бұрын
It was long believed to have been invented by US engineer Edwin Armstrong, but after some controversy the earliest patent for the invention is now credited to French radio engineer and radio manufacturer Lucien Lévy.[1] Virtually all modern radio receivers use the super heterodyne principle. Another example where we will never know who was the inventor for sure!
@Boitaoutix2 жыл бұрын
From Wikipedia (Google translated): It is to Lucien Lévy, head of the laboratory of the Center radiotélégraphique militaire de Paris that we owe the implementation of the superheterodyne although the principle had been indicated by the German Alexander Meissner in 1914. The French Paul Laüt, of the same laboratory that Lévy would also have been a precursor in 1916. Lévy filed two patents on August 4, 1917 and October 1, 1918, and the priority of Lévy's patent over that of Edwin Armstrong will be recognized by the Court of Appeal of the district of Columbia in 1928. The German Schottky who had also filed a patent in June 1918 will recognize the anteriority of Lévy in 1926.
@heribertohernandez88812 жыл бұрын
Good job
@thomashardin9112 жыл бұрын
You look awesome! ⚡️💃🏻🤘
@johnneedy31642 жыл бұрын
Super interesting 👌 👍
@Kathy_Loves_Physics2 жыл бұрын
Thank you so much 🙂
@jmguevarajordan2 жыл бұрын
Armstrong knew about the idea of the superheterodyne when he was in France. My guess is that the idea of the superheterodyne was known by many people, in fact Armstrong acknowledged it, but Armstrong took it, improved it, patented it and made it commercial. Armstrong was 'doer' and not just a 'thinker'. Unfortunately, he made a big mistake thinking that Sarnof(f) was his friend.in addition, Armstrong belonged to an 'era' in which inventors could become rich with their inventions, but that 'era' was over after ww2 and Armstrong did not realize it.
@belperflyer7419 Жыл бұрын
As a schoolboy in the 1950s I used to build single valve tuned radio frequency (TRF) receivers with positive feedback (reaction) to increase the sensitivity. The problem with TRF isn't so much the high frequency but the fact that any amplifiers need to be able to cope with a wide range of them. The big advantage of the superhet is that it changes the incoming RF into a single intermediate frequency (IF) and the following stages can be designed more easily (470khz for AM or 10.7Mhz for FM is common). Only one detector is needed in either case unless a double superhet is used to improve selection. FM just needs a different type of detector from AM - the rest is almost the same. The development of the relationship between Marconi, Armstrong and Sarnof (I'd never heard of him) and the creation of RCA was particularly interesting. The attempt to restrict receiver technology to the USA was clearly not completely successful as there were numerous radio manufacturers in the UK before WW2 (and elsewhere). I worked for one of them as a teenager (Murphy Radio) and occasionally was tasked to check the so-called museum stock of their early models which I loved. So well explained again. I was already familiar with the technology but the history was mostly new.