82. AM Radio Basics - A Block Diagram

[@reverendstabard17]

I started building this kit and go so interested in radio and RF that I got my ham radio license. I've not finished the kit yet, too many other projects! lol. I started 2 years ago. I keep coming back to your videos because as I learn more, I can get more from what you're presenting. Thank you for your effort. I'll understand exactly how all this works (except the magic part) eventually. Thanks again!

[@SailingRuneStar]

I use this kit in a college course I teach and your series has helped me further my own understanding of it. Thank you for what you have done here!!

[@jeffharrison1090]

I suppose the 455khz modulated wave out of the mixer is an industry standard, but exactly why? Is it because 455khz is an easily amplifiable frequency that the rest of the internal radio components won't have a hard time with (inference)? Or perhaps music which has a wider bandwidth than voice will be reproduced better? At 10 khz bandwidth does 455khz ensure that range of audio sounds are reproduced more faithfully? Thanks for the video illustration!!!

[@tadonplane8265]

The “super” in super heterodyne was actually short for supersonic. That term was used in the early days of radio to describe any signal with a frequency higher than the 20KHz limit of human hearing.

[@marinvidovic763]

Very good presentation !!! Tanks for your time and effort. Lot of interesting details to pick up here !!! I just realised an interesting idea ...in this moment : In "*any SuperHet. system" 80% of the inside of the receiver is always desling with 455 kHz waves - (!!!) irespectively of the Original differences between diferent transmitted Radio STATION FREQUENCIS . Basicaly - a super-Het receiver I first stage !!! - copies inteligent info= ((Amplitude modulation )) onto the internaly created 455kHz waves ... ... and Then... eliminates everything else out... so ... after that (!!!) the rest of the aparuts is much easier to design and cotrol/ = keep.stability - as every radio station will gbecome {a 455kHz wave} in there. With imprinted its audionsignal ( program) on the top of The uniform 455kHz wave. I am Wright or wrong here ????? P.S. Thanks for NOT just throwing some techno jargon arround ... and instead of atracting a novice into the Field - ... (scarring a shit out of him/ her). " 62 yoa kid playing again" .

[@pstowitts]

I really enjoy your videos. Thank you for making them! I just finished the AM portion of the Elenco AM/FM kit and I ran into a problem when I assembled the separate transistor amplifier portion. Once I installed the amp into the 8 pin socket, the header pins, being bigger than the DIP pins, spread the contacts within the socket to the point where the LM386 chip wouldn't work any longer. I replaced the socket and then put a "sacrificial" socket on the end of the header pins that allows me to insert the amplifier without damaging the socket. It doesn't hold it very well but maybe you or someone else has a better idea on how to deal with this issue.

[@wagsman9999]

Very interesting, and well-explained.

[@t0raneko]

Thank you thank you thank you for restarting this. I blew out the am section of my elenco radio trying to align it and for the life of me can't find out why or what component is bad.

[@suhailasaba1051]

24:29 Don't we need to have a capacitor after the diode to pass the carrier frequency to ground as we do with the superhetrodyne system and then have only the intelligence signal go to the audio amplifier ? Thanks for the video.

[@TheOffsetVolt]

Yes, you are correct but this is just a block diagram so not much discussion of the actual components. The demodulator will need a low pass filter at the output.

[@suhailasaba1051]

@@TheOffsetVolt Thank you for your explanation.

[@electronicssciencebysherry5050]

Amazingand incredible videos keep it i av learnt a lot 4rom u. Thanks and do more 4 us am most interested in amplifiers and radio making.

[@TheOffsetVolt]

Thanks, will do!

[@Scrogan]

Do I really want to watch a half hour video going over the specifics of AM radio? Yes I do.

[@willbrooks3490]

This is all new to me and so these are likely very dumb questions. Your presentation involves getting only 455Khz at 2nd AM Amplifier stage. But what use is only 455Khz when the AM spectrum at lowest band is 535Khz? There wouldn’t be anything to hear? So, is the signal further amplified after 2nd AM Amplifier stage? Or is it the case that purely for convenience to illustrate the entire process you chose 1000KHz for simplicity? Thanks

[@Wtfinc]

How does the fm detection work? Like am is easy but fm is stuck in fm

[@drstrangelove09]

Why cannot the am signal (after amplifying and filtering) just be sent through a diode to just recover the audio?

[@Scrogan]

Neat video! I was wondering if it would be a fun project to make a direct-mixing AM receiver, where you heterodyne the 1000kHz RF signal directly with a 1000kHz sine oscillator. Back when the superhet was developed this wasn’t an option, but if you locked a PLL to the RF signal and used its output as the oscillator (give or take a phase shift) , you’d be able to directly get the audio signal out with a single-pole low-pass filter. You’d need a tuning circuit and maybe an RF amplifier circuit on the input to ensure locking, but these days even a cheap op-amp can handle a few MHz. I think the whole of the AM band is in the range of a bargain-bin CD4046 and NE612, which is certainly more interesting than a DDS, but making a discrete VCO and ring mixer would be a nice challenge too.

[@fabienburguera386]

Thank you

[@davidluther3408]

GOOD REVIEW FOR ME.

[@TheQuantumFreak]

Awesome.

[@TempoDrift1480]

This is a little further into what I follow. I need to find something a little more elementary.

[@linkavichtruousky1]

Thank you

[@TheOffsetVolt]

You're welcome