Simple Regenerative Receiver For The 40m Amateur Radio Band 

David let me jump out of my bed and check the schematic and I'll get back to you right away. I also found one mistake in the drawing I made. Simple not critic. I'll write back in a bit.

OK... so... from the base of the transistor to the center pin of the potentiometer you have the 4.7k resistor.... the potentiometer is 22k... the other pin of the 22k potentiometer goes to the 10k resistor... and the third pin goes to ground. The mistake I made in the drawing... I will update the schematic tomorrow... the 100nF capacitor going from pin 3 of the LM386 IC that goes to ground... move that before the 10k volume potentiometer. Put it between the output of the 100nF capacitor that comes from the RF side ( audio output ) to ground. Pretty much same as it is now just before the potentiometer not after. As it is now because of the potentiometer combination with the capacitor is acting more like a tone filter than volume control ))) Let me know if you understand what I meant. 73.

@@dxexplorer All ok many thanks for your rapid response dave c

Great Dave. 73

Thank you so much. It is indeed... is like... I'm a little kid building my own toys hehehe... I'll always love and appreciate those more 😁😁 73.

Thank you. Hehe I miss building stuff this way. It just takes time and patience... and I don't have much time lately so I pick the easy way. But maybe this winter I get to build more stuff this way. 73, YO6DXE.

@@dxexplorer Oh, I know what you mean. Next one I do I will try this circuit! Thanks for sharing it!

@maskddingo1779 Always a pleasure. Thank you as well for watching.

I do too. I also used it a lot in many transmitter project... simple ones with only one transistor... or tiny transceivers usually with one or two transistors. I still can't believe that I get nearly 1W out of them... with this tiny transistor. So far I only got to burn one... my fault for pressing the key for too long )) 73

@@dxexplorer I remember my used was a 2N2222A model and hope this will be forever for generations😁 It is good to use a 2N2219 as a second stage HF amplifier. 73

@@jamesho703 I agree, I hope it will last forever ))) About the 2N2219 ... I couldn't find any, so I just replaced it with the 2N2222 ... better than nothing )) 73.

Have a look on the blog... you have two articles with this version of the receiver... but very much improved. 73

Thank you Bob. Ohhh yes the drawing was wrong. I updated the schematic long time ago 😁. 73, YO6DXE.

Yes indeed. Actually that is the main purpose.. the preamp thing is secondary. 73, YO6DXE.

That is great to hear Renato. Ohhh yes the voltage regulator should increase the stability even more.... and the varicap idea it's great. I always tell people that they are free to experiment and get the receiver in the desired band or frequency as they with to. Can you help me with the schematic of the preamp ? I tried one as well for the same reason.... but I just couldn't get it to work as the LM 386 was always going into oscillation. Here is my email: contact@dxexplorer.com ... 73 my friend.

@@dxexplorer Soon I'll be home and I'll send you ok 73!

@@renatoalves2282 I got them..... thank you so much. And I love yours by the way. 73 and have an amazing weekend.

@@dxexplorer other tests that I did with varicap diodes that give good range are 1SV149 and BB112, these reach the bands of 60.49.40 and 41 meters,it is necessary to use a 10k multiturn potentiometer. I will continue doing other tests. :)

@@renatoalves2282 That sounds amazing. I was hoping I will have time today to add one more video, but I just got home and I have to leave again. So I'm looking forward to the results you will have ) 73 my friend.

Thank you Mark. 73 and happy Sunday.

Thank you so much. Not perfect... but it was the best I could with the knowledge I had )). There is an updated one now on the blog. Two versions actually. 73

Thank you for the kind words. Ohhh I'm far from talented hehehe. Still learning... and lots more to learn. But I'm trying to do the best I can ) 73

Thank you so much. Wow I didn't think of that... to combine a little of the old with the new. I will do that.. you made me curious hehehe. And I think I just have another idea now too let's see if that will work ( ha ). 73 DE YO6DXE.

Thank you so much. Some turn out good... some not so much. I think it depends a lot of the capacitors used in the circuit as well... and the voltage stability as well. I could build three identical receivers ... none would be the same unless the quality of the parts is the same ))). I like diode tuning just because is hard to find good air variable capacitors... and when I do find them they are way too expencive. P.S. On the blog article I have the latest schematic I am using and also a PCB design. 73, YO6DXE.

@@dxexplorerYou're right on all counts. And thanks for the schematic update and information. Here's an article I found in the last few months. On page 5 there's a lot said about VFO stability. The part you mentioned about voltage stability is discussed, too. Online there's s few low volt regulators specified (advertised / promoted) as "precision" regulators. However, I've seen some regulators that say they're precision and according to their data sheets they're no more tight voltage tolerance regulators than any run of the mill regulators, so watch data sheets closely. There's an old, nearly forgotten VFO that gives really low drift. Some builders made videos showing how stable they are. The name of that VFO is "Franklin VFO." Maybe you already heard about it. Here's a link to Part 2 of a Franklin circuit: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-fRz9i3HFhAU.html It's found on MIKROWAVE1 channel. He gives good tips to get it working and shows how stable it is with a very convincing demonstration. There's a few things different about the Franklin oscillator. First it it uses 2 transistors instead of just one and second it uses a few "gimmick" capacitors to achieve feedback. The video gives good information about those capacitors. It's relatively easy to get oscillation. Good luck.

@southernexposure123 Ohhh yes I did heard about it and love that one. I like the videos as I learned a lot from them since I didn't had books and magazines... but then I got the book as a PDF and learned a lot more. I find old school analog VFO's very exciting. They are a lot like fly fishing. You put a lot of patience and work in getting them to work well and stable... but then is all just fun and joy 😁.

@@dxexplorer Oh I meant to include: There's a few large variable capacitors on Amazon, but they cost more than I want to give, around 38 dollars each. I did find some transistor sized variable capacitors advertised as 365pF maximum, so I bought a set of 5 for around 10 dollars. However their maximum capacitance is really only 165pF. I found a few old weathered ham radios and I harvested the tuning caps from those. The Vernier drive still works. I also got the tube load and tune caps out of the tube section, too. Oh, I have an idea of how to slow down the tuning of little capacitors. If I get that idea to work I'll post a video. You'll understand if I just say the idea is to add a couple of (not sure what to call them) pulleys? to use as tuners. The one I'll turn with my fingers will ne a really small diameter and the one attached to the actual capacitor will be a much larger diameter. There'll be a string that goes between those two pulleys. I'm not sure yet how to prevent the string from slipping. Maybe put a lot of bees wax on the string to give it traction against the pulleys?

@@dxexplorerUnderstood. I started tying flies again a little in the last few months, too. I'm about to gather the parts for the Franklin in a short while and see how it works for me. I already have some NP0 capacitors and a few C0G caps. It'll be an interesting experiment. I found the Wes Hayward book "Solid State Design" PDF and I have that one in paper anyway. I also have the Doug De Maw QRP little blue book. I almost read all the words off the pages a few decades ago. THEN life's little distractions made me drop out of building projects because of working so far from home. I barely had enough time to commute and get a short nap before beginning the commute for the next day. Oh well. I have the time to get back into building now.

I was using the same for both... 10k... but different circuits. I wasn't happy though so I came out with different solutions )) Have a look at the latest videos about the receiver. I think I put the links in the video description. 73 and thank you.

Thank you so much. I am literally working on the latest PCB design as we speak so now people can also order PCB board for any project posted here on RU-vid or in the blog articles. 73, YO6DXE.

Que bom que gostou meu amigo ... Espero que ajude. Os melhores votos da Romênia. 73

Obrigado Daniel. Dê uma olhada no artigo do blog também (coloquei o link na descrição). Mudei um pouco o esquema e também há um design de PCB. Não é um receptor incrível, mas acho que é fácil de construir e me ofereceu muita satisfação e muitas estações recebidas. 73, YO6DXE

Thank you 😁🙏 73

Hi Rob... Yes of course I can make a video. I will put it on my to do list then... I have to build a few for different things so I will post it pretty soon. About the LM 386... I thought that as well. The one I had it was "stolen" from my 49'er QRP kit hahaha as I had none available. It was the 300 mW version. But now I'm using the 1 W version and the output is the same. I tried all possible configurations but none seem to work. But... I think I discovered a mistake in the schematic about the 100 nF capacitor that goes from pin 3 to ground... that one I was supposed to have it before the potentiometer. So I will make the change and see if I can use other configurations having more audio output with ought having the IC going into oscillation. I will post another video when I'm done testing and making the receiver better looking and using a PCB version.... a proper PCB this time hahaha. Cheers and 73.

Thank you so much. 73

Thank you buddy. I hope the one you make now comes out well 😁😁 73

Thank you 😁

I guess replacing bipolar preamp with tunable FET or DGMosFet preamp will give nice performance

@@rakesh00712 I think so too. I must find a nice but simple schematic for that and see the results. I haven't found anything so far that satisfied me and make a big difference comparing to what I have now. 73 my friend. ( email me please if you have any ideas or suggestions: dxexplorer@gmail.com )

I love when I hear a lot from all over the place. Especially lately as I had no time to stay at the transceiver... so I just work with a receiver working in the background ))

I'm working now on a simplified version that will replace all the older ones and I will remove the older videos. Same performance with less parts but better design 😁😁

@@dxexplorer that sounds pretty neat!

That was the idea at first... to be simple to build... use as little parts as possible but still have some decent performance. Something that would be a great radio project for a beginner.

@@dxexplorer that sounds ideal for people like me 😅

@@bass9112 Or like me... is not like I'm some advanced builder in electronics either hehehe. 73 my friend.

Not at all. Is just a simple regen receiver meant mostly for beginners in radio construction. You can play sometimes with the regen control to make one of the sidebands "dissapear" but it doesn't always work well ... talking about SSB and CW.

My pleasure. 73

I know hahaha... thank you. It was a mistake in the drawing but I fixed the issue in the final schematic. Check the video here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-9opbXQFGn20.html 73 my friend and thank you one more time.

Thank you. I need to watch the video again to remember the schematic as now I am using an improved one.

Neata buna..... salutari de la Prejmer.... Sper sa apuc sa iau si eu indicativul curand. O zi faina... 73.

@@dxexplorer mult succes va asteptam intre noi faina lucrare 👌👍

@@tavirasz2760 Multumesc si eu. Abia astept si eu sa pot emite )) 73 si o saptamana superba.

The power LED or the RX TX ones ? The RX TX depends how you set the colors... no need for resistor as they are taking the power from the same resistor output of the power LED and that one already has a resistor )

Ohh wait... I just watched the video... yep I forgot to add the resistor to the power LED in the schematic. But it's fine as tomorrow I'm adding a link to a new properly made schematic on the computer. Thank you ) 73

@@dxexplorer yes, i meant that one. no worry, happens :-)

Yes hahaha... I was thinking that no way... the resistor is there... but that was in my circuit not in the schematic 😂😂

Check the latest videos or the blog article for the latest schematic of the receiver. This were my first tests that I have here in the video. 73, YO6DXE

Yes of course. I used so far 2N3904, 2N2222, BC107, BF200, BF214 and all worked well. Best results I had with the BF214 but is harder and harder to find.

The 3 capacitor symbols which value is it my friend

Not sure if I understand right. For the rx tx switching I just used a simple switch. But if you also want to use the LED indicators... then that depends the voltage you power up the circuit with... for 12v as example I am usually using 680 ohm.

Sorry to hear that James. Is it because of the AM broadcast band interferences ? Or its because of other issues ? I'm happy it works... but I'm a little bored of regen receivers now hehehe. I tried, I like it... but now I also want to try some DC receiver to see the difference. 73 DE YO6DXE.

I put it that way just so people understand that everything that goes to - is the ground. If you are not using a 50 Ohm antenna and you use a wire for example as the antenna... for better reception you connect the - to ground. I hope it makes sense hehehe. But in the video description you have the link to the article where you can download the new schematic and the pcb design that are way better now. Or check the newer version 1.0 Plus as it has an audio preamplifier as well and you can also use a speaker. Let me know if you have more questions. Feel free to email me. 73 my friend.

@@dxexplorer well... thank you. 73 from brasil. 👏👏👏👏👏👏 💚💛💙🇧🇷🇧🇷🇧🇷

Hahaha... si eu ma uit deci nu esti singurul 😅 da pai na... pasiune veche... dar nu ma gandeam ca ajung si pe RU-vid cu treaba asta 😅. Bun venit 😁 73

@@dxexplorer ce inseamna 73? Inca nu m-am apucat de transmit (inca nu am licenta), eu sunt mai mult cu electronica, radio fiind o sectie din ea. Stiu niste coduri Q si reguli dar cam atat cand e vorba de partea ce nu tine de electronica 😄

@@DiaconescuAlexandru2024 E mai bine ca ai inceput cu electronica. Partea de coduri e mai simpla )) 73 e un fel de "salutari" "best regards" )

@@dxexplorer Ahhh, ok, multumesc :)

@YoureNotGettingMyNameDolan cu drag... 88 e sarutari si imbratisari... pentru fete ))

What kind of file ? I am a little confused 😁😁

It depends. I honestly don't know 100% because most of the time I recovered parts from old boards. I think the only "expencive" components could be the potentiometers and the multiturn potentiometer... anything else is pretty cheap. I would say that with the prices we have here in Romania, converted to US dollars maybe something around 20 - 30$. It depends on the prices of the components in each country.

@@dxexplorerthank you for your input on my vague question. I just wanted to ensure that there wasn't some hidden million dollar pots before I tried to sort the parts. I am pretty new with building small kits but this one has me excited.

I have this one close to my heart as it got me back into the hobby and thanks to this receiver I now have my amateur radio license. I was dreaming about it since I was litttle... I never had the time for it though. I am pretty sure that if you insist you could make it way more expencive hahaha... but my idea was to keep it as simple and cheap as possible so anyone can build it... mostly from recovered components.

This one actually stands out to me at its total lack of stuff that's hard/expensive to buy, no air variable caps, easy to wind air core coil, no FETs that haven't been affordable common parts going on a decade now, etc. All jellybean parts,.@@josephroblesjr.8944

Not sure to be honest. That's a good question. Technically with the proper modifications I guess it should. But the Q factor or the LC circuit will change a lot... and I think the transistor may not go into oscillation. So for that there would be needed some more changes into the resistors and maybe also the regen potentiometer. I'll have to try one day.

Pretty sure the -9v is a typo.

No... it's just the regular + and - from a battery as usually. I noted the - as ground simply because I also use that as ground and wanted to make it easy to understand.

Have a look at the article on the blog please... I have some really crazy days at work and not much time to reply here. dxexplorer.com/sputnik-regenerative-receiver 73, YO6DXE.

Maybe Google is not translating well... but I can't really understand the comments. What do you mean by remote reception ?

22mm... its in the very big drawing of the coil in both articles I think ))

@@dxexplorer I see it now!!!! Thanks

@@grampysmagic3327 Always a pleasure. 73

It says13 mm on the drawing

The one in the video was the very first schematics I started experimenting with. The one on the blog and in the latest videos is the newest one and the result of all the experiments made in this older videos.

73, YO6DXE

I haven't tried but I don't think it will work on VHF. It's designed to work for HF only. 73

Have a look at the new article and schematic. This one in this video is the older version. dxexplorer.com/sputnik-regenerative-receiver/

I found it .45 mm

It is indeed yes. Because it will change the inductance value of the coil.

It depends... you can use a proper tuned antena, or you can just use some wire hanging between two trees. The shortest wire I tested it with was around 6 meters.

Sorry for the late reply... I was busy trying to finish the video for the new version. Have a look at the last two videos.. you may like it better and sounds even better as well. I think the transistor you asked about is equivalent to 2N3094... I use it for the RF and the AF preamp... I think it could work for the regen as well to replace the 2N2222... I just can't remember how well it performs. But if I remember well the difference is not that big. Try it and see how it is. 73 my friend.

@@dxexplorer Thanks, actualy your reply wasnt late at all tbh, iam gonna build the circuit so the transistor can be easily swapped, (like not that i desolder the transistor and the whole circuit falls apart, thanks for help, iam gonna check the new video, actually the reasson why i commented on this video is because i actually dont really need the RF preamp, i have a 20M long antenna so i dont really need a preamp.

Excellent idea my friend.... I should do the same when building test circuits. It's a struggle to solder and unsolder. About the RF preamp.... not really necesary but useful. It's just a few more parts. The thing is that the regen receivers radiate a little bit of RF... like a tiny transmitter... not much though. But sometimes that can bother other amateur radio neighbors. So the preamp prevents that RF going into the antenna. Another useful thing is that sometimes signals are way too strong... and using the potentiometer it's easy to limit that signal so it won't overload your receiver. 73 and I hope it all works well.

@@dxexplorer Thanks

Always a pleasure my friend.

Sorry I write in English but I am on the phone and I don't have a translation app. I don't know much about that multimeter. I have a few from Kaiweets but even if they measure frequency from power supllies... they do not measure RF frequency. If you want to get the receiver in the 40m amateur radio band... the easiest is to use an online SDR later in the evening when the propagation is good... you must listen to the SDR... and then try to make adjustments to the receiver until you are able to hear pretty much the same thing. If you used the latest schematic that is on the blog now... then you just play with the trimmer capacitor... I think is C16... and the value of C15 the one that is in parallel with the trimmer. This so you don't have to keep modifying the coil if the inductance of the coil is not exactly as mine. Usually this is the easiest way to tune the receiver in the right portion of the band with ought a frequency meter. Even though... it is a bit time consuming ... but this is how I did it for a long time for all my receivers until I managed to get a frequency counter. Maybe you can buy a cheap one like the one I used and posted a photo of it in the blog article. They have them pretty cheap on AliExpress if I remember well. They are not perfect... but they help you a lot. Let me know if you got it tuned... if not send me an email from the blog and I will try to help you. 73, YO6DXE.

@@dxexplorer Thank you for your detailed answer, I really like the way you shoot videos, you are great! I will definitely try to set it up as you wrote to me, I will definitely let you know how it went 73

@user-us9sv4be5y Thank you so much my friend. I've been really busy with work lately... but I hope I calm down slowly and I have time for more videos. Ok let me know how it goes... good luck as I know is not so easy with ought measurement equipment. 73 my friend.

Verifique a descrição do vídeo para o artigo do blog. Você tem lá o esquema atualizado disponível para download. Eu só tenho que recalcular a bobina quando tiver tempo. 73

Of course I'm happy to see what you had made. I will come over and have a look in a little :) 73.

Plz can you show me schematic with dds?

Thank you so much. 73

Yes I do have... I just posted on the community tab earlier today hehehe. I am finally a licensed amateur radio operator. I passed the final exam too. Yuhuuuu. Waiting to get my call sign now. Meanwhile I have 30 days to learn Morse code as that will be the main one for me at the moment until I can afford some proper transceiver 😁😁😁 73

@@dxexplorer Darn I didn't see that post. Congratulations for a job well done. Now you can enjoy the hobby in full. No harm in learning Morse, love it myself, it's magic. And now you must hope for a call that 'goes smooth' whilst keying. :-) Take care. Gust ON6KE

@@placeholder-065 I must pick one so I'm searching trough the database to see what's available hehehe. 73 my friend.

@@dxexplorer Good idea. In my time (1974) there was no choosing a call, they gave you one and that was it. Before I forget, DON'T key /QRP after your call, never. Many of us old farts will avoid you for that. Take care Ciprian. Gust ON6KE

Hahaha.. thank you so much. Good to know that))) 73

Ohhhh yes. Especially today when the variable capacitors are hard to find.... Is not as good as a variable capacitor, but it does the job :)

@@dxexplorer you're the man

Hahaha... thanks buddy. 73