AA5 Radio Signal Flow

AA5 Radio Signal Flow

[@frankmooney7282]

I've been away from electronics since the late 80s. At 65 I got my ham liscence and been on a relearning curve for last three years. Thanks for this and other videos which finally give me a ahaaa moment . Your succinct explaination in a short video gelled so much info. Appreciated in this over the hill brain.

[@AllAmericanFiveRadio]

Thanks and your welcome.

[@ranuts2]

Thank you Rick, for such a basic walk-thru. It really pulls together so many things for me. This video is terrific, outstanding, really. You have really raised the bar with this recent graphic. I very much appreciate the time you put into these videos.

[@JeffBishop_KB3QMT]

I know this is an old video, but I wanted to say "thank you." This video clearly explains how the AVC works, including the negative side of the audio signal. That's something I've had trouble grasping, the negative audios impact on the AVC. I knew it was there, but never knew how it got there. Thank you.

[@AllAmericanFiveRadio]

Thank you, and you are welcome. Time does not matter; this is the way it works.

[@aspendesign]

Thanks to you Rick. I'm finally getting it. I have found your videos extremely helpful. I've bought an old Grundig 5077 that needs work and I've been trying to do this myself. I'm a mechanical Engineer and so far my understanding has not been sufficient to do this. The radio has got Hum when you up the volume, Has poor FM reception and the volume periodically changes on its own. It has had most of the Caps changed (by the previous owner) but not all. I was finding the circuit very complex and difficult to follow but slowly with your tutorials it is coming into view. Very grateful to you for your clear and concise videos.

[@AllAmericanFiveRadio]

Thank you, and your welcome. I think my FREE eBook may help. PASSWORD is allamericanfiveradio drive.google.com/file/d/1HHmaWYr7UMACfmS4W5uL6PADoem2KlRp/view?usp=sharing

[@aspendesign]

​@@AllAmericanFiveRadio Thank you Richard. This is absolutely brilliant. You are most kind.

[@AllAmericanFiveRadio]

@@aspendesign Thank you, and your welcome.

[@coptertim]

This may be a primitive design by today's standards however; you have to admire the brilliance of the engineers who designed it. Great video!

[@AllAmericanFiveRadio]

You may like this 100 year old circuit. !923 Vacuum Tube, Amplitude Modulation Detector Circuit in Detail kzbin.info/www/bejne/m2HJkpSuaLipndk

[@danielsteele7544]

Thankyou for being a great mentor and teacher to us out here that are trying to learn. You do so much to help us understand.Great video,I just fixed my first radio ,a bad .02 cap leaking badly to ground on an old Hallicrafters s40a ham set.cut it loose and the old girl came to life with a new 1000 ohm resistor installed that was toast.

[@AllAmericanFiveRadio]

Thanks

[@petercunningham4000]

I realise that this is an old video,. but I have just come across it today. Thank You for a very clear and concise explanation of the signal flow through a radio. Your colouring of the signal path at the different stages makes everything very clear.

[@AllAmericanFiveRadio]

Thanks

[@Bleats_Sinodai]

That was a really great video! I've studied electronics and I got my diploma as a technician, but the course was really short (2 years) so we didn't have time to go too deeply into stuff like that. Now I understand how a radio works. That's really cool!

[@AntiqueRadioandTV]

Wow Rick! I have been in electronics, professionally since the 70's and have NEVER seen a more definitive and clear presentation of how the signal flow in a radio schematic works in all my life. Bravo! If some day you could do the same for a vintage CRT based TV. This would also be absolutely fantastic. Excellent job! The pinnacle of demonstrations.

[@johnallenrichter]

Totally awesome video Rick.... Your patience and expert teaching style have helped me to understand AA5 and other radios so well. It's really humbling trying to find the words to thank you for carrying this knowledge forward.....

[@Lesstroublesleeping]

Extremely informative and thorough explanation. Thanks for taking all the time to put this together and providing the links.

[@AllAmericanFiveRadio]

Thanks

[@vibra64]

Fantastic video! Thanks. Nice refresher for me. BTW in describing the first IF you said the frequency that will be used was 455kc and 455Hz. Just wanted to mention that. Thanks for all your hard work

[@acdcjustthebest....8980]

Thanks very much for getting back, I really appreciated it. This Astor BPJ I was working on was a customer repair, I have been doing this for nearly 5 years and have fixed all the sets I have worked on, probably about 40/50 or so and this fault was really doing my head in as he bought it on Ebay “working” and it had a few loose joints a broken leg of a new cap and a O.C resistor. I have been looking at this for weeks and trying different things, then yesterday the way you broke up this video in stages made me think if I connected some headphones to the input of the power tube after c15 in you schematic that may narrow down the fault which it did. So You did help me. So Thanks again.. Great video

[@AllAmericanFiveRadio]

Thanks This video may help also. Build a Audio and RF Signal Tracer using a Guitar Amplifier kzbin.info/www/bejne/h4bQgXV4o9-eiKc

[@gerrygoyette5891]

Your AM radio videos are the best I've viewed on KZbin! I have learned so much from you! Thank You and keep them coming!I also downloaded you PDF book Thanks!

[@AllAmericanFiveRadio]

Thanks

[@ggattsr]

Thanks Rick for another great video. Watching your videos always seem to increase my understanding of topics I thought I knew. Thanks for re-educating an old HAM.

[@AllAmericanFiveRadio]

Thanks Philip Booth, R13 and R14 are biasing resistors. R14 races the voltage of the cathode 5.2V above ground, R13 sets the bias voltage at pin five for the control grid.

[@abeleballestri612]

Beautiful video how the radio signal goes through all the stages ,from the aerial to the loudspeaker and the AVC circuit very clearly explained how it works as well as the oscillator circuitry. The colouring of the path where the signals go through is simple wonderfully clear. Thanks for the very tutorial explanation and the clear lesson.

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@THOMMGB]

Rick, Thanks so much for showing, with your highlighted schematic, how an AA5 operates. I knew the basics, but your video shows all the details. The good news is that I can re-watch your video as often as necessary until it sinks in and takes hold. Regards, Tom

[@ragbearebikegoodlife6693]

Thanks so much Richard... This is the best video on this aspect of radio that I have ever seen. This really helps to clear things up for me. Thanks for the downloads too.

[@AllAmericanFiveRadio]

Your welcome and Thanks

[@eagle7267]

@@AllAmericanFiveRadio Sadly, links are now broken.

[@TechTins_Projects]

Really nice work Richard!! I particularly like the way you explained about the effective zero output of audio (signal cancelling out) if you tried to sample signal before it goes through the detector. Crucial information explained well. That was great fun to watch!

[@AllAmericanFiveRadio]

Thank you.

[@AllAmericanFiveRadio]

Pin five, a plate, and pin three, the cathode, is a rectifier. It cuts the signal in half. The 155 pF capacitor drains off most of the 455 kHz signal and blocks the audio. The audio then travels down to the high side of the volume control.

[@kd0imp]

Very good explanation! I feel like someone just told me the secret to a magic trick that I've not been able to figure out. Understanding is a beautiful thing! You are an awesome teacher. Keep up the good work.

[@skycarl]

Thanks again Rick. Once again just a fantastic presentation.

[@torcelo]

Thanks for your generosity.

[@AllAmericanFiveRadio]

Thanks

[@windmilljohn]

Fantastic, fantastic video. It clarified a lot for me; albeit I'm late to the party! I just need to clarify for my self the AVC. If it reduces the negative to the grids, I thought that would lower the plate current!. I'll do more reading.

[@AllAmericanFiveRadio]

Thank you , and your welcome. Here are two videos that may help. Automatic Volume Level Control AVC ALC kzbin.info/www/bejne/hIbIo4KFlrB5hpo Superheterodyne AA5 from End to End kzbin.info/www/bejne/nZ3EnKKEg5mfraM

[@windmilljohn]

@@AllAmericanFiveRadio Thank you

[@RandyCornetta]

Great video! I love the simplicity of the AA5.

[@AllAmericanFiveRadio]

Thanks

[@Ronbob59]

This is what I've been searching for, Rick. Thanks so much for posting it...

[@mentalvmaxrider]

Wow!!!! Old upload but so so informative. Thank you for the clear and concise explanation.

[@AllAmericanFiveRadio]

Thanks, age does not mater. The truth is the truth.

[@lengle73]

Thanks for the demonstration, very well put together.

[@AllAmericanFiveRadio]

Thanks

[@Chondrule]

AVC is staring to make sense for me after this video, many thanks!

[@AllAmericanFiveRadio]

You are welcome and I'M glad it helped!

[@HobokenHam]

That was the first, really clear explanation of signal flow I've encountered since I began playing with radios 50 years ago (Yikes, did I really say that? 50 years, phew.)

[@k1rod]

Thanks Rick for this awesome video. I am trying to restore an old Hallicrafters S-38E which I believe is an AA5, just using a slightly different set of tubes. I appreciate all the effort to highlight the parts of the circuit as you were addressing them. This must have been a good bit of work but it makes your explanation very clear. Kind of funny, I just purchased a book about the AA5's on Amazon that appears to have been authored by you! Can't wait to get it! Thanks again. -rod (K1ROD)

[@seongwoonyoon1057]

very good very good very good .. best educational video i have ever seen

[@AllAmericanFiveRadio]

Thanks

[@AndyDaviesByTheSea]

Hi Rick, 13:06 running time but I know it took many hours in the making. I hope your work stays on KZbin for many years as I'm sure your efforts will go a long way to help folk in preserving some lovely old radios that would otherwise bite the dust through lack of understanding. A very useful description in 13 minutes well done! Kind Regards ... Andy

[@rayhindle642]

Thanks for a really detailed explanation, I guess I could troubleshoot an AA5 now without much trouble thanks to you, also helped with all valve radio troubleshooting.....................Ray H. ( from the U.K. ) Liked and subscribed.

[@AllAmericanFiveRadio]

Thank you.

[@AllAmericanFiveRadio]

Thanks Cosmos142857 Yes, the flow for a basic transistor AA5 is the same.

[@K4JOE]

Another great video Rick. I hope you ment 455 kilo Hertz in stead of 455 Hertz for the IF frequency Or for older terms 455 kilo cycles / second. Joe

[@bxb590]

This was much better than just good. Many thanks, I learned a lot.

[@AllAmericanFiveRadio]

Your welcome.

[@appale7]

excellent work

[@AllAmericanFiveRadio]

Thank you.

[@CL-ty6wp]

I received a 5r10 hallicrafters and it is on as soon as it plugs in. The volume has an off but doesnt work, unless it clicks off hard? The powercord comes in with both lead going right to the first tube.- No switch. Also the r19 220 ohm 1w resistor is half broke and reads 120 ohm now. The tuning cord was routed wrong and had to be cut. I ended up just going from knob to pulley above it and it works! I left the back open to look at the variable cap to get an idea where in the frequency I am. Eventually I plan to fix the tuning cord & needle, atleast replace the broken resistor and put a polarized plugged cord on.

[@AllAmericanFiveRadio]

I hope you can continue with the restoration, back to 100%.

[@abeleballestri612]

Ain't was a very tuition way of explaining step by step the path of the signal from the aerial input to the loudspeaker including the circuit for the AVC according to the strength of the received signal . Thank you very much indeed. I think you should print a book accordingly , it would be a bestseller for the electronics basics.

[@dwtees]

Rick, Your explanations for amplifier stage phase inversion, and detection are very clear. Much better than any textbook I have read besides yours of course. I have two questions. 1. When and how is the other detector plate pin 4 of the 12SQ7 used? 2. Is a vacuum tube detector more efficient than the galena crystal or say the 1N34A diodes used in crystal radio circuits?

[@francismannion7075]

Wow that was great , it was a very clear and easy to follow explanation . Thank you.

[@AllAmericanFiveRadio]

Thanks

[@RickO.-vq8oh]

Key note: As C1 is varied, it changes the resonant frequency of the LC Tank circuit - this allows you to tune to the desired station

[@AllAmericanFiveRadio]

Yes that is correct. Superheterodyne AA5 from End to End kzbin.info/www/bejne/nZ3EnKKEg5mfraM

[@DannerPlace]

Very good, thank you for posting.

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@vtradio]

I found the video very informative. I recap old shortwave receivers once in a while, and struggle with the flow of the schematics. Soon, I plan to recap a Zenith 6G601. 73 Paul AA1SU

[@AllAmericanFiveRadio]

THANK YOU!

[@AllAmericanFiveRadio]

Thanks GeoN0JRJ You're welcome to use this video for your ham club, I hope it helps the members to understand superheterodyne receiver's. The two links to the drawings I made to fit on an 8.5 x 11 sheet of paper. Hope this helps, Rick

[@microreniassance2929]

Excellent video! Great analysis!

[@AllAmericanFiveRadio]

Thanks

[@AllAmericanFiveRadio]

Thanks Douglas Tees I thought I sent a reply but I can't find it, must be another KZbin improvement. In the circuit the vacuum tube would work better because it matches the impedance of the IF secondary. Generally, solid-state is more efficient but it is low impedance.

[@JDBolt1958]

Thank you for sharing this knowledge. Marvelous!

[@AllAmericanFiveRadio]

THANK YOU!

[@williefleete]

excellent video, learned quite a bit on how superhet radio's work

[@ivanmollo8495]

Muy bien explicado su video acerca del funcionamiento del receptor superheterodino, muchas gracias. CE1GWX, 73.

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@granz8855]

great explaination of the signal flows. thank you

[@AllAmericanFiveRadio]

Thanks and your welcome.

[@LyonsArcade]

Thank you Sir, i'm still learning the basics and this is very helpful. I don't completely get it but i'm starting to :)

[@AllAmericanFiveRadio]

Thank you. These videos may help. Superheterodyne AA5 from End to End kzbin.info/www/bejne/nZ3EnKKEg5mfraM Superheterodyne RF Mixer Visual Color Demonstration kzbin.info/www/bejne/hZi4ZpR3r8-FY80 Superheterodyne Radio, heterodyning frequencies together, how it works kzbin.info/www/bejne/a3eQmn6fodmYqbc

[@AllAmericanFiveRadio]

Thanks John Richter

[@AllAmericanFiveRadio]

Thanks Joe Allen

[@AllAmericanFiveRadio]

Thanks Joe Minor Yes, I put a note in the video and I corrected the downloadable file.

[@patrick4228]

If the question is: for what purpose do you use the internet most of the time? Then watching, enjoying and learning from KZbin channels like AllAmericanFiveRadio would definitely be in my top 3! I can’t thank you enough for all the time and effort you put in these video’s. Oh, and also thank you for the free ’The Vacuum Tube Shortwave Radio' E-Book I just discovered! Now I can watch one of your video’s, and then read, and than watch another video, and then read some more,…

[@AllAmericanFiveRadio]

Thanks you Patrick. I'm glad that you find my KZbin site useful. When I started my KZbin I was wondering if any body would be interested.

[@patrick4228]

Thank you for your personal reaction Richard, much appreciated. I can only hope you have as much pleasure making your video's than all we viewers have when watching them.

[@AllAmericanFiveRadio]

Thanks jim maddog If C-17 opened the audio would have a high pitch to it, possibly generating noise. If C-17 shorted the audio output would be greatly reduced and possibly damage the 50L6 and the audio transformer.

[@kka10001]

Thanks, I can understand the way you presented it. Lot of info

[@AllAmericanFiveRadio]

Thank you, and you may like this video also. Superheterodyne RF Mixer Visual Color Demonstration kzbin.info/www/bejne/hZi4ZpR3r8-FY80

[@AllAmericanFiveRadio]

Thanks sahhaf1234 Mostly want C-17 does, is it attenuates the high audio frequencies a little.

[@Museudaeletronica]

Please, what is the make and model of this radio? Thanks! Congratulations on the video!

[@AllAmericanFiveRadio]

Thanks. It is a Croley E10BE

[@AllAmericanFiveRadio]

Thanks Ron Pearson

[@jonathangauci2182]

Thanks for great explanation, i have one doubt about capacitor of avc. Positive of capacitor to ground but as i know its non polarity capacitors used.

[@AllAmericanFiveRadio]

Thank you, and you are welcome.

[@jonathangauci2182]

@AllAmericanFiveRadio can I ask what type of capacitor it is that one that you talk about for avc?? That you had positive goes to negative?

[@AllAmericanFiveRadio]

Thanks Philip Booth

[@AllAmericanFiveRadio]

Thanks Tony T.

[@barn5923]

love the videos

[@AllAmericanFiveRadio]

Thank you, and your welcome. You may like this. How Superheterodyne Works kzbin.info/www/bejne/oILHY3-cibSUas0

[@willbdiggin3967]

Great video Ric, it's much easier to see on video compared to reading many pages in a book. This will help many people learn much faster.

[@LouinVB]

Excellent lesson.

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@tennesseered586]

Very well explained. Thank you.

[@AllAmericanFiveRadio]

Thank you, and you are welcome.

[@guerramar]

Good afternoon and thanks for reading. I have an American radio that does not work because the local oscillator coil is broken. And I know it's broken because I got an ebay radio for parts and extracted the coil and put it on the radio mute and it works fine. The thing is, I want to make an equal coil but I do not know how to do it. I thought it was simple but I stumbled with difficulties. Measuring the new coil, between the first winding there are about five ohms and with an LC meter read about 148 uH and then between another second winding about 112 uH, but the coil has yet other turns that must be in the air and act by induction. One part of the coil goes to the short section of the variable capacitor and the other to ground. And the other two points go to cathode and one of the bars of 12BA7 (pins 1 and 2). Well, I've made a coil with these approximate values ​​and it does not work for me. I should have done something wrong and for this I ask for help. I send you the radio layout. Very grateful for his teachings on video. I am a follower of yours in YT. Gerardo. NOTE: Although the schematic carries the series 12SA7, 12SQ7, etc., my two radios carry the series 12BE7, 12BA7, 50C5 and 35W4.

[@AllAmericanFiveRadio]

Glad you got it working!

[@ericklassen742]

Thanks for this video Richard. I refer to it often. Can you tell me the purpose of the plate on pin #5 on the 12SQ7? I don't seem to get it cleared up in my mind. Everything else that you covered in good.

[@AllAmericanFiveRadio]

Pin#5 Plate and the Cathode are a Diode. This diode cuts the modulated RF in half so that the AM signal can be amplified. (AM Detection) This video may help you understand this process. If you have questions, let me know. How Superheterodyne Works kzbin.info/www/bejne/oILHY3-cibSUas0

[@ericklassen742]

Thanks Richard. I finally got some time to look at that video. I appreciste all your work over the years.@@AllAmericanFiveRadio

[@mikepasko7493]

Thanks for the great info.....

[@AllAmericanFiveRadio]

Thank you and your welcome.

[@pd1rwk825]

Thank you, thank you, thank you, for this fine explanation. Van you do this also in a BX373a?

[@AllAmericanFiveRadio]

I have colored the section of each tube and labeled it's function. If you send me an email I'll send it to you, Make the subject Philips BX373A. [e-mail]

[@ovi_4]

Really good explanations regarding the signal path and everything else within the radio. Thank you. Have subscribed. Just a beginner here trying to learn some radio basics. I have a question however, regarding the last part of the video (the Automatic gain control path via the R5). Why is it also tied to the Oscillator coil (B terminal) ? What does it do. ? Isn't that a somehow a typo on the drawing? Or. would that be a way to reduce the oscillators 455KHz level and in turn further reducing the overall amplification (in the event of a strong station ? Thank you.

[@AllAmericanFiveRadio]

R5 supplies the DCV stored by C8 for the ALC. It is common that a component has more than one function. C8 stores the ALC voltage, it isolates the OSC secondary from DC ground, and is the RF path for the OSC secondary to ground. I will do a video on this soon. Here are a few videos you many find helpful. How Superheterodyne Works kzbin.info/www/bejne/oILHY3-cibSUas0 !923 Vacuum Tube, Amplitude Modulation Detector Circuit in Detail kzbin.info/www/bejne/m2HJkpSuaLipndk MY FREE EBOOK Password is allamericanfiveradio kzbin.info?event=channel_description&redir_token=QUFFLUhqa2hhVTRycWdJd1FUbTFCZWNmdGtQNlZCRmEzd3xBQ3Jtc0tuOFQ2bFhRcWdjdUdIcUREcnZFaHc0M2xURGhITVRuWDE2cGlDakdYUF9uODktNzc3TVRJTWdROUt6R3NLN2lla3hFS2lIM0RnOXR1dXFxMGx2cUNtWDhXb1Zvc2RCbGQxTThoendmN2E5R0lJdmI0Yw&q=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F1HHmaWYr7UMACfmS4W5uL6PADoem2KlRp%2Fview%3Fusp%3Dsharing

[@AllAmericanFiveRadio]

Thanks vibra64 Yes I put a note in the video and corrected the drawing

[@AllAmericanFiveRadio]

Thanks Andy

[@dman52566]

Great video!

[@AllAmericanFiveRadio]

Thanks I hope this video helps.

[@lupojacobo9892]

Thanks you Boss. I will try this on my equipment schematics

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@lyntonprescott3412]

Brilliant! Many thanks from a novice. Lynton

[@AllAmericanFiveRadio]

Thanks

[@radiotvrepair1059]

Thank you very much , good explanation of the signal flow

[@AllAmericanFiveRadio]

THANKS

[@TheCondoInRedondo]

Great job! Could you please explain the purpose of the signal transformers? The output transformer is clearly to impedance match the tube driver to the low-ohmage speaker. But if the first I/F transformer is for adjacent signal rejection, what does the second transformer do?

[@AllAmericanFiveRadio]

The first IF filters out over 90%, the second IF filters out over 90% of whats left. So with two filters the usable signal is almost 100% pure.

[@TheCondoInRedondo]

@@AllAmericanFiveRadio Thank you for taking the time to explain.

[@AllAmericanFiveRadio]

@@TheCondoInRedondo Thanks and your welcome.

[@Cosmos142857]

Beautiful! Thank you for this video. I have so much difficulty following these more complicated circuits and these 'signal trace' videos are very helpful and very much appreciated. I suppose the tube could be replaced with transistors?????

[@SatishVasane]

Thank you from India

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@AllAmericanFiveRadio]

Thanks blackcorvo

[@rob_scooter6199]

thank you.

[@AllAmericanFiveRadio]

Thank you, and your welcome.

[@AllAmericanFiveRadio]

Thanks AntiqueRadioandTV

[@sahhaf1234]

This is an extremely nice video. I couldnt understand one thing, though. What is the job of C17 and why he takes a middle tap from the primary of C3 when he connects in the power supply. Anyways, thanks for the very informative video. Actu

[@Kennynva]

Can you use a 455khz crystal where the first IF can is to do the same thing..???

[@AllAmericanFiveRadio]

455kHz crystal filter.

[@jrallen870]

Great video... love circuit walk throughs

[@stevenm6592]

What it’s the purpose of the 12SA7 pin 4 screen circuit 12SK7 pin 6 screen an pin 3 screen ground 50L6 GT pin 4 screen

[@AllAmericanFiveRadio]

12 SA7 pin 4 is held positive which helps in pulling electrons off of the cathode and directing them to the plate. This grid also helps in mixing the radio frequency and local oscillator together. 12SK7 pin 6 is held positive which helps pull electrons from the cathode and directs them to the plate. pin 3 is held negative. Some of the electrons that reached the plate bounce off. This grid being negative helps direct these electrons that bounce off the plate, back to the plate. 50L6 pin 4 is held positive which helps pull electrons from the cathode and directs them to the plate. This increases the amount of electrons that reach the plate which increases the current. Superheterodyne RF Mixer Visual Color Demonstration kzbin.info/www/bejne/hZi4ZpR3r8-FY80

[@AllAmericanFiveRadio]

I think my FREE eBook may help. PASSWORD is allamericanfiveradio drive.google.com/file/d/1HHmaWYr7UMACfmS4W5uL6 PADoem2KlRp/view?usp=sharing

[@sahhaf1234]

Sorry, in my last message C3 must be T3 (ie, the transformer) and the last word "Actu" must not be there. Thanks again,

[@johnallenrichter]

Hi Richard. May I add a link to this video in one of my videos? This is such a great explanation of the AA5 I'd like to send viewers here if they would like to get a firm understanding of the AA5... -John

[@AllAmericanFiveRadio]

John Richter John RichterSure you can link to this video. I'm glad you like it.Rick

[@RadioHamGuy]

Great explanation and very helpful.

[@saarike]

Your videos are really nice!

[@AllAmericanFiveRadio]

Thanks

[@schweizerd6303]

Thanks for the explanation it was very detailed, useful and easy to understand! I am new to the hobby and trying to restore a RCA Victor V305 1950s AM Radio. It has a highly similar concept to this one but uses (Loop Antenna)===>>12BE6===>>12SF7===>>12SG7===>>2x35C5===>>Audio Transformer===>>(Speaker) instead, with a selenium rectifier opposed to 35Z5 shown here and dual gang capacitor for antenna and oscillator tuning. Instead of having one 35C5 tubes at the output end, they put two in parallel. The previous owner swapped one of the tubes for 50C5, so it now has one of each at the output. What advantage is there to have two tubes, and why would they have used a 50C5 instead? Also could the phono jack be used as input from a mp3 player for example? It has two phono jacks, one labelled 78-33 and the other 45 not sure what the differences are electrically.

[@AllAmericanFiveRadio]

I'll look up the model and try to answer your questions.

[@AllAmericanFiveRadio]

Found the schematic. The difference between the 35C5 and 50C5 is the filaments, 35VAC and 50VAC respectively. So I don't think the 50C5 is doing much. Contact me at this email and put the subject as RCA V305. [e-mail]

[@AllAmericanFiveRadio]

My free eBook (password is allamericanfiveradio) The Vacuum Tube Shortwave Radio www.richardmcwhorter.com/vacuumtuberadio/

[@donalddesnoo5303]

I went to a electronics high school class in 1959 our final exam was to draw that from memory .I was only one to do it doubt it would have worked 🤗

[@AllAmericanFiveRadio]

I made an AA5 and chassis, in High School electoric shop class. 59-63

[@billhubbell3414]

I am unable to find your eBook mentioned in the comments.

[@AllAmericanFiveRadio]

password is allamericanfiveradio drive.google.com/file/d/1HHmaWYr7UMACfmS4W5uL6PADoem2KlRp/view?usp=sharing

[@MrSeeuu]

Very nice explanation.

[@AllAmericanFiveRadio]

Thank you, and you are welcome. You may be interested in this video. How Superheterodyne Works kzbin.info/www/bejne/oILHY3-cibSUas0

[@RadioDude1969]

After the 12SQ7; how can C15 conduct the rectified signal? Capacitors can only conduct AC. This is DC (varying). Can you please expain.

[@AllAmericanFiveRadio]

+RadioDude1969 I'm going to talk about the positive half of the modulated RF signal. As you noted the height of this half of the DC varies. When the audio signal is louder the height of the DC increases proportionally and when the audio signal is less the DC decreases proportionally. Let's start at the highest point, the loudest, as the signal becomes less as we mentioned previously the DC becomes less and to do this the electrons are actually moving in the opposite direction from the highest point, even though the signal never becomes negative the electrons have to move in the opposite direction otherwise it could not decrease. When the signal becomes strong again the electrons reverse direction again. So when the signal is moving up to a strong signal the electrons are moving in one direction and when the signal is decreasing the electrons are moving in the opposite direction. This is the definition of AC. So what this signal has is DC with AC floating on top of it. As you mention capacitors block DC but the changing direction of the top of the DC is AC and it is this AC audio signal that passes through the capacitor.

[@RadioDude1969]

+AllAmericanFiveRadio Thank you!