The Superheterodyne Radio: No really, that's its name

that internet pun was so painful, it hertz

I didn't know that Capacitors were called Condensers in the past. They're still called "Kondensator" in German.

It's amazing how complicated "simple" things like a radio really are.

Listening to the interference between waveforms is something I was trained to do as a musician. If you’re playing in a band or orchestra, it’s really important to be able to hear that “wobble” of interfering wave forms because it means that someone is playing out of tune. The explanation given in your video is MUCH better than the explanation I was given when I was first learning how to tune my instrument. Great video!

In 1980 when I was in high school, transistor radios were all the thing. One day at lunch when we were all outside, I was playing my transistor radio on an Atlanta rock station 96.1FM someone else standing near by was playing a country radio station at 106.7FM on their handheld FM radio. We wanted to compare radios to see which handheld FM Radio was better. We first wanted to see which radio would play the loudest. So my friend turned up the volume all the way playing a country song and I did the same with a rock song. We brought the two radios together to see if one could be heard over the other. To our amazement, my friends radio quit playing the country station and started playing the rock station. Other kids standing around started laughing. I was wondering what was going on. He moved his transistor radio away from mine and it started playing the country station again. We were all dumbfounded...??? There was another kid playing a pop station at the time at 92.9FM and the country station and pop station played together. We put the rock station 96.1FM together with the pop station 92.9 and got the same results as each radio continued to play the perspective stations. We put the Rock station 96.1 together again with the country station 106.7 and the radio playing the country station started playing the rock station. We never really did compare the radios, but we did know that Rock music would beat out country music every time. I later in life learned that the effect was known as Super heterodyning. I repeated the experiments years later with two totally different radios and got the same effect. I thought it the strangest thing.

You are seriously my favorite account on YouTube. Not afraid to dive into the real technology left behind by our shiny gadgets of today. And you are really true to yourself and what motivates you! Thank you so much for your videos, even on Christmas! Happy Holidays.

7:09 I love how those old engineers put ball bearings in there, they wanted the radio to last forever. Not like now they don't even put bearings in the wheels of some kids' bikes.

As a dude with no background in engineering, your videos are a really good insight on how tech evolved over time. This is seriously good content.

Safety precaution: This is an AA5 radio without a power transformer, therefore No isolation from the AC line. Also, originally it would have been fit with an unpolarized power cord meaning that depending on which way the plug is inserted into the wall outlet there is a 50/50 chance of having the chassis at or close to HOT power line potential. For safety power cord SB replaced with polarized line cord making sure to wire it correctly if not already done. Any capacitor from line cord to chassis SB replaced with XYZ safety cap of same value. Getting a knob for the on-off volume control is a must, even if it doesn't match, touching that bare shaft is an extreme shock hazzard. That is a nice radio and worth a good cleanup and restoration. Just my two cents hoping to keep you safe.

Heterodyne RF oscillators are also how a theremin works, too - one is at a fixed frequency and the other is varied by the position of the player's hand, and the resulting beat frequency is a tone in audio range. I built a theremin from a kit in high school, and was floored when I realized half-way through that the darn thing was pretty much just a messed-up AM radio.

When I was young and had all ratty furniture, I had an amplifier/receiver missing the lid. For fun I wrapped part of the loop FM antenna around the antenna coil core. My friend who knows even more about electronics than I was visiting and scoffed, "What do you call that?" I replied, "That's Super-DUPER-heterodyne!"

I am a Polytechnic student and watched this video WAY before I got this topic on book. When I finally got it on book, I faintly remembered this video and rewatched it. This video is so much more comprehensive than the book! I have found more comprehensive explanation from yours two channal than I got from my books. Things like Heat pumps, Radio stuff, TV Things , CRT, Imaging technique, EV and so much more. Please keep making these videos. For your casual viewers (like me) and also for engineering students(also like me). Thanks!

The superhet today has been partly replaced by direct conversion, iroinically what we used to have before the superhet. The advances in digital technology means modern radios used for mobile phones/wifi etc.. convert directly to baseband without any intermediate frequency and use DSP techniques to provide the selectivity. Direct conversion has shortcomings but in the digital domain they can be tolerated as data can always be re-sent and forward error correction exists too. Some manufacturers such as Ubiquiti in the states have overcome the problems with direct conversion radio chips by adding a superhet stage that acts as a tracking filter. This converts to an I.F. then filters there then converts it back to the original frequency albeit now with just the channel needed present. Easy enough to do as you only need the one injection oscillator to convert down and back up again. They call it AirPrism which is a nod to the early Intersil prism radio chipsets that used superhet techniques as standard. Back in the AM radio days a 455khz I.F. was fine as the image was always out of band, however later they added double conversion. a common frequency for this was 10.7 MHz . this placed the image 21.4 MHz away and meant the entire shortwave band could be tuned from a single radio. they used double conversion so they could do most of their gain and selectivity at 455khz and have less stringent filtering at 10.7MHz. Even when broadcast FM radios came out the first I.F. was 10.7MHz , hence the band was usually 88 to 108 MHz, a 20MHz span , meaning the 21.4MHz image was again out of band at either end (depending if they mixed high or low). Later of course as the spectrum got more crowded and higher frequencies were used they had to increase this I.F. further and 21.4 MHz became popular then 45 MHz and even 90MHz as the technology, mainly in Crystal/ceramic filters improved and so did the high frequency performance of active components. Later still the early WiFi chipsets used SAW (surface acoustic wave) filters that were smaller and cheaper to make than crystal ones and operated in the hundreds of MHZ range. Now we are back at square one, using direct conversion because the technology we have allows it .. Full circle :)

The outtakes at the end are a real education in how difficult it is to speak clearly and accurately into a microphone. Makes me feel better whenever I stumble over my words.

The hair, the jacket, the voice, the wit... The more I watch this chsnnel, the more i love this guy. It doesn't hurt that his content is interesting, extremely well-researched and always clearly and rigorously explained.

As a youngster, I explored ( took apart ) many old radios obtained from various sources. I never had a clue how all that worked. Yours is the first real explanation I ever heard. Thanks for sharing.

I love your old "cringetastic" videos, though! They're what got me subscribed to you in the first place.

1:51 "ok, how does that help?" My response to everything I've looked at while trying to learn the dark arts of RF wizardry.

I'm really blown away by what a brilliant idea the whole superheterodyne thing is. You did an excellent job presenting it, not to mention figuring it out and how to demonstrate it. Also, your attention to details like mouth noises and such helps make yours an easy channel to watch.

6:38 fun fact, capacitors are called "kondensator" in Polish. I often mix those terms and get "condensator" in English and "kapacytor" in Polish