David Sarnoff, Howard Armstrong & the Superheterodyne Receiver 

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.

Armstrong deserves a Hollywood biopic... tragic tech hero of the 20th century.

We had a big party in1970 when Sarnoff retired. However we didn’t invite him. He was a real Party pooper.

I’m a broadcaster, so Armstrong has always been my hero.

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 RU-vid about this great inventor , and you have new precious historical photos. That's great ! It's terribly interesting ! Thank you ! 73 !

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.

This is the most interesting series on RU-vid that I have ever come across.My utmost praise for Kathy and her content.Just fantastic and enlightening!

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.

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.

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!

Absolutely love your tuition. Right at my level . Less is more. Thankyou

The knowledge u spreading is priceless.. very nice .. i am watching u from india 🇮🇳

LOVE these 10min clip- format!

We take radio for granted: not now ..!! Love the history you give !!

Kathy, you are simply the greatest.

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.

My father worked along Edwing Armstrong until his death at the Alpine Tower in New Jersey.

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.

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!

Brilliant!!! Absolutely loving these videos.

thank you - you're the first person that makes me understand the superhet system and I tried many before!

HEY MR. ARMSTRONG THANK YOU FOR ALL YOUR GREAT INVENTIONS MY FRIEND!

This is a great channel,keep up the good work!!

A most stupendous telling - of a story rarely told. Thank you for creating and sharing this.

Highly informative and motivating. Thank you.

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.

Lovely presentation

That was great! I have always been a fan of radio, specially vintage radio. Let's go to the rest of the FMstory!

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.

Well done, my dear!!! Keep up the fabulous work!!!

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.

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!

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

You have an amazing way of presenting these facts

You're such a great vlogger. I really love these.

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.

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.

Just found your channel! You deserve millions of subscribers. Very happy. I love this stuff.

Love your channel Kathy 👍

Great story - have to keep watching!

I enjoyed you video very much, thanks. Sarnoff was the proverbial guy who pulled himself up by his own bootstraps.

Love your channel. There is nothing quite like it for drama and accuracy.

Great video. Great history.

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.

Great video and great explanations - thanks for sharing!

Great video for enthusiasts of radio !

These are great videos, thanks so much!! Subbed up also

I got a degree in mass communication and I’ve seen your videos for the past week and learned more from them than college

Very cool stuff! Thank you...

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, 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.

Empire of the Air is a very interesting documentary of early radio. Nice video!

Outstanding work!

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.

Thank you , I Learned so much , I am hooked

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.

Just so interesting, thank you

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

Great storytelling

I love the line "Think Fiddler on the Roof, but with a painter". That is absolutely priceless.

The first receivers I worked on in the Navy, back in the 60's had BFO controls on the front panel.

No questions, just CUDOS for great vids..

Excellent and accurate presentation.

Great job

Fascinating, loved this. Subbed too.

Wonderful!

You are amazing.

Very nice!

Thank you!

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.

The Sarnoff Marconi connection is amazing. It’s as if the universe opened a door.

I am truly honored Kathy for meeting you 💜

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...

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.

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

Hi Kathy, Well told story; I would only ask that you provide sources or credits where credit is due for your photographs. Some that I personally scanned for the David Sarnoff Library are now held by the Hagley Library, and the Armstrong/WJZ photos from the Harry Houck Collection or Columbia University's Armstrong Collection. Thanks!

thank you for your wonderful program. l wonder whether one can control the volume by changing the current thru the filament. usually it's done by changing the voltage amplitude to the grid.

Very interesting - thanks👍. Definitely interested to see more videos on various pioneers of radio. Marconi was certainly an interesting character. Although, as a Scot, your thoughts on James Clark Mawell would be interesting.

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.

Fab video!

Ok I'm hooked on your videos now.

Great story. Subscribed. 👍

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.

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!

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

just read Empire of the Air and i'm addicted! thank you for the video! what did you think of Oppenheimer? Nolan should do the story of radio next!

Looking forward to your book! We need a cast of characters map...LOL...

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.

Good job

I enjoy these videos immensely and have to watch multiple times to retain about half of the information. One small correction, Guglielmo Marconi is pronounced Gwee-el-mo, he is not a Guillermo.

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!

Excellent video just found your channel d subscribed !

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

Super interesting 👌 👍

Learn a lot more from you than my physics class

of course impossible to resist video

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!!!

You look awesome! ⚡️💃🏻🤘

very good

great!