#355

Vacuum tubes are an old, but fascinating technology that was used before transistors were invented. We can learn how simple circuits were back then if we build a kit like this three-tube receiver. Join me on my discovery journey. I have no clue about what I am doing. But, after the video, we will know more, I am sure. Whether the receiver will work or not.
I am a proud Patreon of ‪@greatscottlab‬ , ‪@ElectroBOOM‬ , ‪@ELECTRONOOBS‬ , ‪@EEVblog‬ , and others
No Docker, Microsoft Teams, Zoom
Links:
Three Tube Receivers: www.aliexpress...
Example of a variable capacitor: s.click.aliexp...
AD9850 Frequency Generator board: s.click.aliexp...
Tecsun PL-660: s.click.aliexp...
Variable Capacitor: www.hdic.com.hk...
HackRF one original: amzn.to/34n6SP5
HackRF one Clones: s.click.aliexp...
Mr. Carlsons video: • How A Tube Works
Better diagram: theradioboard.c...
The links above usually are affiliate links which support the channel (no additional cost for you).
Supporting Material and Blog Page: www.sensorsiot.org
Github: www.github.com...
My Patreon Page: / andreasspiess
Discord: / discord
If you want to support the channel, please use the links below to start your shopping. No additional charges for you, but I get a commission (of your purchases the next 24 hours) to buy new stuff for the channel
My Amazon.com shop: www.amazon.com...
For Banggood bit.ly/2jAQEf4
For AliExpress: bit.ly/2B0yTLL
For Amazon.de: amzn.to/2r0ZCYI
For Amazon UK: amzn.to/2mxBaJf
For ebay.com: ebay.to/2DuYXBp
www.facebook.c...
/ spiessa
www.instructab...
Please do not try to Email me or invite me on LinkedIn. These communication channels are reserved for my primary job
As an Amazon Associate, I earn from qualifying purchases
#no#midroll#ads

[@MrCarlsonsLab]

Thank You for the kind mention Mr. Spiess!

[@AndreasSpiess]

You deserve it!

[@erygion]

I love your channel Mr. Carlson!

[@PhG1961]

@@AndreasSpiess Indeed he does !

[@marcdraco2189]

@@AndreasSpiess Both channels are soooo addictive! :)

[@Mosfet510]

You have a great channel too!

[@vincentpertoso3148]

I am 71 years old now so I not only remember tubes I learned basic electronics in the 50s from my father starting at age 5. I was building small radios at 10 and repairing tube TVs with my dad. Well I am retired now having been an Electronic Engineer for over 35 years. Got lots of old tubes around so can't wait to build a tube RADIO again.

[@AndreasSpiess]

Enjoy! You were even earlier with starting with electronics than I did. But you were lucky to have an involved father. Mine learned me to work with wood...

[@Kysushanz]

Ha, you were 71 three years ago - I'm 74 now so we are the same age. I had a next-door neighbour [Mr Auld] who was a senior person in the Post Office Telephone Exchange in my city and he was very interested in Radio. In his basement he had quite a big workshop. He initially got me interested in DXing and I had an old 11 valve, Atwater Kent radio which pulled in stations on Broadcast Band from some great distances. Anyway, he gave me some old Radio Engineering magazines and in one of the magazines was an article about "Hikers Radios" [I think from the 1920 ~ 30's]. They progressed from a Hikes One, Hikers Two and Hikers Three. Anyway, I got all excited about this as I had already built a Crystal Set under his instruction so I decided to make a start on a Hikers One. Immediately, we had to have a valve substitution because of non-availability. I can't remember the valve we had to replace, but I clearly remember the substitution - it was a DL92A valve. [It was a miniature valve]. I worked on that radio and even made a cabinet for it so that when I finished it, I was very proud. Being a one valve set, I had old headphones connected and could lie in bed at night, listening to the radio and mum or dad wouldn't know I wasn't sleeping! I found that by increasing the voltage to the valve, I could get better reception and stations further way - I also noted that the valve started to light up like a light bulb as I applied more power. In my quest to get more and more stations, one night my Hikers One didn't work! I planned to build the Hikers Three but never got around to it. Thanks for your article, it has brought back many memories. RIP - Mr Auld.

[@jimcompton4587]

My Morse is very rusty. But after several replays I got "Hi KZbinrs". Thanks for the fun video. 73's

[@AndreasSpiess]

The text is right! 73.

[@PhG1961]

Wonderfull project. Only 3 months ago I donated all my remaining tubes (quite a lot..) to a radio museum here in Belgium. Together with almost all my prehistoric radio's and a few TV sets from the late 50's/early 60's. I had no choise, they took too much space. However, I still have 3 left. One I inherited from my grand parents and is dated 1927. Your video is sure a trip down memory lane....

[@AndreasSpiess]

So you radios and tubes have a good place! I also once had a tube radio from 1925. But unfortunately, when I left home, my parents also once thought, they have not enough space...

[@PhG1961]

@@AndreasSpiess Yes, throwing it away would break my heart. I have a weak spot for old radio's and tubes.

[@Jogris]

Thanks for taking the time to make the video! I built the kit with point to point wiring and could not get it to work. Soon as you said L1 and L2 were “confused” that sorted it out for me. I know this post is a year old now, thanks again and keep up the great content!

[@AndreasSpiess]

Glad your radio works now!

[@justusgronts3882]

I built a three tube five band radio from a Heathkit kit back in the 60s as a kid. Started my career in electronics, was a great learning experience. Nicely done video.

[@AndreasSpiess]

Thank you. I was not involved in tubes when I was young. Only linear amplifiers had them, of course.

[@McTroyd]

I was fascinated by electronics from when I was young. My grandfather even bought me my first soldering iron when I was 10. But, it wasn't until I stumbled across Mr. Carlson's Lab a couple years ago, that I finally understood how analog circuits work. You are quite right; Paul Carlson is not only an authority, he explains himself and his process well. I'm hoping to use his methods to restore an old (circa 1952) AM/FM tube radio that I bought from a local antiques market. (Even broken it was US$90! These things are getting expensive.) Mr. Carlson suggests using them to listen to period-correct music. It's a rare opportunity to hear how that music was experienced back then.

[@AndreasSpiess]

So good luck for your restauration. It seems easy if you watch Mr. Carlson on KZbin. But I am not so sure about reality ;-)

[@McTroyd]

@@AndreasSpiess Thank you. Mr. Carlson makes a lot of things look easy. Benefit of experience, I guess. He does indicate what parts tend to take lots of time and meticulous, precision work. On that basis, I'm considering it an "informed decision." 😁

[@Richardincancale]

I think my first electronics project was a single valve radio of the same sort of design but without the audio amplifier - just used high impedance headphones. You really could hear the world. That got me started over 50 years ago!

[@AndreasSpiess]

These are the "live changing events"... Today it is not easy to get such high impedance earphones. They are low impedance these days adapted to today's voltages.

[@Richardincancale]

Andreas Spiess Yes indeed. Had a teleprinter (50 baud) in my bedroom aged 16 - and 50 valve ‘modem’ to drive it from my valve radio. Worked in telecoms all my life, from X25 data networks to microwave, fiber and satellite and mobile networks! An early hobby turned into a life!

[@dogastus]

I find it quite amusing to see such a crude radio being set up with all that expensive test gear - spectrum analyser, function generator etc. 'When I was a boy' I only had the receiver parts, no test gear. I think your next project should be a superhet radio :)

[@AndreasSpiess]

You are right! But you had more stations near you who could serve as a "function generator". These days it is hard to find strong stations... I am more in SDR than in superhets.

[@zachreyhelmberger894]

What fun!! Thank you for making this video! I remember when I was a teenager and I made a regenerative receiver out of a single 6BF6 vacuum tube and some coils on toilet paper tubes (it took the poor salesman forever to find one in his stock)!! I got the schematic from some hobby magazine. It was wonderful to hear all of these shortwave stations on the radio. I even made a coil for the CB radio band (27Mhz) and it actually worked! I could hear the locals talking on their CBs. The selectivity was not all that great so I would hear multiple channels at once but what fun!! The original circuit used a potentiometer to vary the positive feedback but it was really scratchy and really hard to get that super high gain without tripping it into oscillation. So I modified the tickler circuit by winding a pancake coil on a piece of cereal box paperboard and stuck it inside the main coil and arranged it like a butterfly valve so I could vary that magnetic coupling to the main coil as you turned it open or closed. It was AMAZING how smooth it was and I could sneak up on the gain to ridiculous levels and really pull in the shortwave stations!

[@AndreasSpiess]

You are welcome! The problem with winding the right coil and finding a good distance to the feedback coil is still there. One thing, however changed: We do no more have a lot of powerful radio stations on those frequencies.

[@jimgbf]

Enjoyed the video. Although not with vacuum tubes, I built a small transistor radio in the 60s from a kit. It was exciting to hear the AM station when it first fired up.

[@AndreasSpiess]

Today it is probably no more easy to get AM stations, at least not in Europe. Most are switched off by now.

[@ElectronixHobbyist]

Hello, I have tried to decode the Morse code that you Played in the Vaccum Tube Radio 😁 .... .. -.-- --- ..- - ..- -... . .-. ... "Hi KZbinrs" Is it correct ??

[@AndreasSpiess]

Yes, it is correct (at least the characters). I do not use points and dashes, I just listen to the signal ;-)

[@campchennai]

I like most your lucid way of explaining everything and taking pains to respond to most of the comments..My father a Physics teacher in India , motivated me in the 60s. An enchanting Hobby these low voltage tubes!! Lovely video .I'll be 80 soon and I want to build a One valver one day.I have a liking for those 4 pin directly heated Triodes for their sheer simplicity. Crosley pup is a fantastic radio .( I have'nt seen it physically though)

[@AndreasSpiess]

I am glad to have an 80-year-old viewer! I hope I will be able to do electronics when I am your age (only 15 years from now ;-)

[@fotografm]

HI KZbinRS. Thank you Andreas for this wonderful video. It took me straight back to my childhood where I bult many such projects. I never tried low voltage directly heated valves however. I was used to 300V / 6.3V PSUs as an 11 year old and I survived ! My memory is now flooding with ECC83, EF50, EL84, KT88 and QQVO6-40 ! 73 de G4EYR

[@AndreasSpiess]

You are right with the morse signal. It was probably better to start young. Now I know what can happen and fear high voltages...

[@newburypi]

This really carried me back. My very first electronics build was a Heathkit "All American Five" superhetrodyne AM radio. FM was still in the future :) Certainly the kit was much better documented and all the components fit the assembly. One thing that just came back to me... there was no printed circuit board. The components were either mounted to the metal chassis or strung between the mounted components' leads. A few inches of fabric tubing kept connecting wires from shorting. It was powered from 120 volts, yet still available for construction by youngsters. No health and safety committees back then. Thanks, yet again, for an interesting and memory jolting video.

[@AndreasSpiess]

That´s great! I never built one of those back then. I assume quite a few viewers will share similar experiences...

[@r1273m]

Heathkit were great. Back in the 1960's I built their Oscilloscope, it used either a 3" or 4" CRT. It worked perfectly from first switch on. The instructions detailed the length and colour of every piece of wire used. As you say no H&S then. Here in the UK we are on 240V and can only imagine the voltage on the CRT anode!

[@dennisyoung4631]

Built an HR-10b in 1973-4 - in the eighth grade. Needed help getting it running, as I had not yet learned to be “methodical enough.” Built the 6t9 transmitter from scratch. I learned about “Bee-Plus” (b+) voltage then, and got *tossed* by the 275+ volts on the plates.

[@robertsmiczsmiczamplificat593]

A great video. I’m a tube guy. I grew up in a radio and tv shop in our garage through the 60’s and 70’s. My dad had my head in the back of big color TV chassis’ at 5 yrs old. Of course teaching me what to and what not to touch. I still build, modify and repair tube gear. I work on a fair amount of tube ham radio gear, and a lot of guitar amps. There is so much work, because most techs wont mess with tubes because of the near 50O vdc B+ on many tube guitar amps. I have also made many tube RF amps for ham radio. Spanning from 100 watts to legal limit and more. It is an old technology, but nothing sounds as good as a Tube/valves in a guitar amplifier. One issue with tubes in guitar amps is that you need to turn the volume up very high to get that nice tube distortion that most players love so much.The tone is very sweet, but the amp needs to be very loud to get that warm tone. I make Tube Adapter Converters to replace typical 5-35 watt pentode tubes with a 1 watt miniature pentode tube. See www.smiczamps.com/tacs. This allows guitar players to get that great tube tone at low volume levels. Many audio tubes are manufactured to this day in China, Russia and other eastern European countries, such as the Slovak republic. There are many current manufacturers of tube guitar amplifiers due to the warm harmonic rich tone that tubes generate. Not even modern class D devices can generate that wonderful tube sound. Tube generated Even harmonic distortion which is pleasant to the ears. Modern Solid state device produce odd harmonic distortion which is not very pleasant. I am involved in all types of electronics, but i will always love the simplicity and sound that tubes generate. I loved the video. 73 de N1FQF.

[@AndreasSpiess]

You seem to have a lot of experience in tubes! It is interesting to see that distortion is a good thing in your profession! We mostly try to avoid it ;-) Concerning your "tube size reduction": An interesting idea. I am sure your customers are happy that somebody builds these things. One thing I wonder is if this distortions could be "simulated" by today's DSP technology and then amplified by a distortion free amp.

[@robertsmiczsmiczamplificat593]

Andreas Spiess . Everyone is trying to simulate tube distortion with DSP. So far nothing is as good or better then tubes yet, in my opinion.There are some pretty good sounding plugins out thete, but they are still not the same. They are an ok simulation, but not the same. Tubes have even harmonic rich distortion that is just so wonderful sounding. All the solid state device distortion, (even modern class D amps) is very bad sounding when clipped. It has hard clipping when hitting the power supply rails and generates much more odd harmonic distortion which is not pleasant to the ears. Tubes have a nice soft clipping effect filled with beautiful even harmonics. Tubes run in depletion mode where SS devices run in enhancement mode. In listening to music you don’t want distortion? When it comes to guitar, the tube distortion started a while new world of music beginning with the legendary blues. I am involved in all matters of electronics. I have been into ham radio since i was a kid and i was involved in wireless transmission most of my working career. i just fell in love with tubes in the late 60’s and have not been able to break from its grips. I made tube guitar amps that ran on battery back in the late 90’s into the 2000’s. It was the worlds first and i think only all tube battery powered amp? I don’t build amps commercially anymore? I still build a few one off custom amps for a small group of customers. The tube adapters are an easy way to get that cranked amp tube distortion without waking up the neighbors or having the police at your door. Its an ancient technology that still can not be beat for tone with guitar. It’s a bug i just cant seem to shake. Plus i just love the smell of hot tubes. Its the while thing. The tone the smell. It’s tremendous. I’m building a couple of tube amps as we speak. I have tried every DSP amp simulator i can hear, but they are just not there yet. They sound similar, but they just don’t have the dynamics and the rich harmonics. Take care. Thanks for the email. If you need any tube info ever? Let me know. I have lots of stuff rattling around up there in my brain. I have hundreds of tube books. Theory, circuits, specs. Also scanned to files as well.

[@AndreasSpiess]

I can imagine that clopping on modern amplifiers do not sound good. And good to know that I have a specialist in my viewers!

[@robertsmiczsmiczamplificat593]

Andreas Spiess. You have Mr Carlson as well. He is another professional tube head. I watch all his videos as well. Thank you. Take care my friend.

[@GuilhermeHuet]

Hi Andreas, I love tubes, specially in the audio environment. This one was one of your best videos! Congratulations to explaining basics on electronic to young hobbits.

[@AndreasSpiess]

Glad you liked it! I am not too much in audio and therefore do not have a lot of knowledge, unfortunately...

[@gwesco]

I "cut my teeth" on vacuum tubes back in the mid '50's. The first digit of the tube number is usually the filament voltage. Most rectifiers like the 5U4 and 5Y3 were 5 volts. Most other tubes were 6 volts. Some were 12 volts with a center tapped filament so they could be wired in parallel to work off 6 volts. Battery powered radios in the mid 50's tended to use the 1 and 2 volt tubes because they had a couple of batteries, one for filaments and a higher voltage for B+. Typical B+ in old tube equipment ran as high as 700 VDC in some cases. A few dozen milliamps but enough to give you a big jolt.

[@AndreasSpiess]

Good information on the numbering. Thank you! In military we had transmitters with 10kW output. They also had very high anode voltages. I never liked it :-(

[@irvingc4255]

Brings back memories! As a teenage amateur radio geek back in the day I built a 144MHz (2M band) power amp using push-pull 2CX450 valves running 400v or so on the anodes. About 150W RF output from memory (it was almost 55y ago). I don't think my parents would have approved if they'd have known. How I managed to avoid electrocuting myself is amazing! RF power transistors were way outside my Saturday job income, but army surplus even then was cheap and plentiful... though it was several months of saving for those valves.

[@AndreasSpiess]

150W RF output on 144MHz 55 years ago. This was marvelous! My first 2m rig had 2 watts if I remember right :-(

[@emptech]

When I was in high school in the '60's, each student built a radio receiver. The tube sockets were mounted on a block of wood. The resistors and capacitors were soldered to terminal strips. The coils were wound on plastic tubes, the number of turns specified. I remember it was silk covered wire, not the varnished wire you are used to. The tuning was done with a variable capacitor. What was different, this was called a TRF receiver, a Tuned Radio Frequency receiver, not the superhetrodyne receivers which were very common. Actually, many car radios were TRF radios, if I recall, they had better selectivity than the superhet radios. Printed circuits did exist but they were beyond our capability. Later on, I built a darkroom timer, it did have a printed circuit board and a single 12AU7 vacuum tube, a simple multivibrator circuit, you would count the ticks to know how long your film or paper was developing. I also remember when a single BIT of storage in a computer was a master-slave flip-flop, made up of two vacuum tubes. ONE bit, not a byte. It took lots of tubes to make up the memory that a computer needed in those days, no wonder they needed all that air conditioning. Yes, the good old days. Jim

[@AndreasSpiess]

If I see what technology we have today at nearly no cost, I would say, today is much better. But of course, we were young then and did not know how fast things will move. I am glad that I was able to see all the development in electronics of the last nearly 50 years. What a journey if we look back at your tube radio on a block of wood. But still: They worked!

[@peter.stimpel]

I am very happy tubes are no standard for hobbyists anymore. My wife would kill me if I had an eqivalent of valves laying around here. The small transistors and diodes can hide ;) Thanks for this journey into history

[@AndreasSpiess]

You are right. A "tube PC" would be too big even for our living room ;-)

[@hesspet]

If you are a hobbyist who builds guitar amps with valves like me, you have other problems than small glas tubes, trust me. Ask my neighbours about testing 100w tube amps........ :-)

[@peter.stimpel]

@@hesspet In my family, we play drums. No need to tell me about angry people around me :D

[@gendragongfly]

Thank you very much for the video, I've always wanted to build an amp or radio with tubes but I never did it because of the high voltage, high price and sometimes poor documentation. This video will be a great reference for anyone who wants to build a radio with tubes. I think I'll start looking for a nice kit now 😊

[@AndreasSpiess]

Enjoy the build when you got the right kit!

[@dennisyoung4631]

Depends on the tube(s). There are a fair number of tubes that use (relatively) low voltages, e.g. 1t4, 1ad4. The latter is especially interesting, as 1) it’s very small; 2) it has a fair level of gain; and 3) it runs well on less than 45 volts. I’ve run these on 27 volts in a small regenerative radio.

[@planker]

Oh boy, we just had the video on the Transistor Survival kit. I commented on that one but I was a little shy, I guess the 2n2222 is my favorite piece of silicon but not my true love. Fat resistors and tube sockets now occupy my dreams. I haven't figured out how to drive NeoPixal's with a 6au6 yet but I'm on it. Excellent work on your build.

[@AndreasSpiess]

Cool! Hopefully you will get a tube device running!

[@TheBalconyWorkspace]

Holy Moly! I never expected this kit would be sold to Europe! The tubes inside were made by Beijing Electron Tube Works, and this is exactly the same kit which I bought here in China!

[@AndreasSpiess]

AliExpress is quite good in bringing the Chinese products to the world ;-)

[@mawamatakama5150]

I love the clear sound and the warming light of the vacuum tubes

[@AndreasSpiess]

Unfortunately those miniature tubes do not glow a lot. The heating power is too low.

[@jackpatteeuw9244]

Best explanation of a 3 tube receiver I have seen !

[@AndreasSpiess]

Glad you think so!

[@adzak6569]

16:01 In the photo "Bolero" a Polish tube radio receiver produced from the beginning of 1960.

[@AndreasSpiess]

Thanks for the info. I did not know. It looked nice ;-)

[@mikegross6107]

You think YOU didn't know what you were doing, just imagine putting together a TV kit! That's what I did in my younger days (thanks to a kit company named Transvision). I DID have some experience with a soldering iron and use of a volt/ohm meter but I succeeded! This was in the '60's when everything was operated by with tubes, impossible nowadays with transistors (or almost impossible). This clip brought back a lot of memories!

[@AndreasSpiess]

That happened to quite a few commenters. I was a little too late for the tubes in education. So I had to do it now ;-)

[@beekeeper8474]

I love tube equipment. They sound so warm and clean.

[@AndreasSpiess]

Unfortunately, I am too old to hear a lot of difference :-(

[@Uncle-Duncan-Shack]

Hi Andreas, Another great video it is. Just yesterday I watched Paul Carlson aligning a six tube Fada which he restored. That Vedolyzer was quite a bit of test equipment. I was not aware that one can get these radio kits, maybe something to try. Some early radio sets of course did live of batteries and taps of the battery bank at various voltages for the heaters and the plates. The battery box was bigger than the radio. The stuff worked, they did a lot with very little as we say. Kind regards, Duncan

[@AndreasSpiess]

That is what fascinated me, too. With one tube (or later transistor) they built a working radio! When I was young we bought old military batteries and gave it to friends to touch both ends. What they did not know before they tried was that their voltage was 110 volts ;-)

[@Uncle-Duncan-Shack]

Andreas Spiess that’s funny yes

[@G56AG]

For my 8th grade science project I built a 3 band AM and shortwave receiver from a semi kit. This was in 1960 so it was all vacuum tube construction, built on a metal chassis, all hand wired, no printed circuit boards, built on the family breakfast table. I took it to my Dad's TV shop and he walked me through the alignment using an oscilloscope. Quite a project for a 14 yr old kid, it took me around 45 hours to build. The semi kit included a metal chassis, a screen printed faceplate, and a whole bunch of parts, I think it had 8 to 10 tubes, the best thing about it was it had a good construction manual that walked you though the build.

[@AndreasSpiess]

So you were lucky to have a dad which knew the stuff! But it was quite complicated back then without PCBs I assume...

[@SynZ777]

Build a simple vacuum tube amplifier. I always love to watch the tubes glow.

[@AndreasSpiess]

Greatscott tried one last Sunday. But he thought there is not a lot of value... Nixies are probably better if you like the glow.

[@waynethompson8416]

Really enjoyed this video! Nice bit of history as well. Paul, "Mr. Carlson", is doing a video on one of my favorite radios. It is the BC348 which was used in aircraft during WWII. Among the very interesting things about it to me are that it uses an IF frequency of 915 Khz, and the 4 gang tuning capacitor ( 4 sections each 14-331 pF) which includes a potentiometer attached to the shaft of the tuning capacitor! The potentiometer is used to keep the noise level somewhat constant from low end to high end of each band. Low resistance at the low frequency end of the band, and high resistance at the high frequency end of the band.

[@AndreasSpiess]

The engineers back then had to be very creative, I think. Their technological possibilities were much smaller than what we have today.

[@freesaxon6835]

Interesting video, always thought valve radios have more soul. The more expensive valve radios used to have what was called a " magic eye tuner " It was basically a valve, and you either viewed it end, or side on. As you tuned a station in two green beans of light got closer.

[@AndreasSpiess]

I remember these "magic eyes". But I do not know which signal it was connected to.

[@d942yd42]

kzbin.info/www/bejne/o6emqK2CpNyghdE He repairs a valve radio and builds a magic eye in one video

[@jimharman5748]

@@AndreasSpiess The Magic Eye was connected to the receiver's AGC or Automatic Gain Control, which adjusts the gain so strong and weak AM stations come in with about the same volume. The gain adjustment was done with a "remote cutoff" pentode whose gain depended on the amount of grid bias.

[@mrdovie47]

When I was in my teens, I bought a multiplex converter kit for a tube FM radio. I had to modify the FM demodulator, but I got stereo out that sounded wonderful to me at the time. You hardly ever hear a stereo FM receiver called a Multiplex Receiver anymore, but it sounded cool in the day.

[@AndreasSpiess]

Interesting! We had good solutions when we were young. But it was often replaced with even better stuff! The development during my career was mindboggling!

[@rbphilip]

Dude! You're only 4 months older than me. :) A lovely video. Exactly what I imagine all my Ham radio friends did when they were kids. While I was toggling boot loaders into early PDP-8 computers. :)

[@AndreasSpiess]

Two different careers... But it was easier to make money with computers than with radios ;-) So your decision was probably not bad.

[@rbphilip]

@@AndreasSpiess Yeah - computers have done me well over the years. Still are!

[@fotografm]

@@rbphilip ooh - I was doing the PDP8 thing back then aswell. All those toggle switches just to start up the punch tape reader :-)

[@rbphilip]

@@fotografm Exactly! We've advanced more than a little with modern bootloaders! On the other hand, my octal-to-decimal skills were much sharper back then!

[@fotografm]

@@rbphilipand my morse code reading skills also just got sharpened :-)

[@ricksteiner1250]

This video is nice. I agree the schematic isn't worth the trouble but your process if putting this together showed me where I went wrong and how to fix... Just not sure where the speaker is connected...thanks!

[@AndreasSpiess]

I hope you will find out!

[@DanBowkley]

We should do a crowd sourced tube radio. Schematic, board layout, the whole works. BOM readily available on AliExpress and boards from JLC or PCBWay. 73 de KG6OHK

[@AndreasSpiess]

Everybody is free to start such a project. I would probably join with one of the "tube" KZbinrs. On this channel, the interest in such things is not too big...

[@patchnplay]

I've seen these kits on Ali as well but never bought them exactly for the reasons you encountered: bad documentation and unclear expectations. Very glad you made this video about them!

[@AndreasSpiess]

So maybe you try one now...

[@patchnplay]

@@AndreasSpiess I might do so but I hoped the kits were designed for the FM band so it would be usable as a normal radio. Probably not possible due to the high frequency of FM? I'm a licensed HAM as well but living in the city the reception of the 40m band is terrible due to interference. A good magnetic loop antenna might be a first project ;-).

[@y2ksw1]

I found today an old valve, EC86, before I checked on KZbin ... I made transmitters and high quality audio amplifiers. In one word, I love valves! Even more than computers 😄

[@AndreasSpiess]

As I said, I do not understand a lot of tubes. But it was interesting for me to dive into the matter. It is somehow similar to transistors from a logical point of view. And interesting how these engineers solved the problems with "primitive" tools compared to now.

[@y2ksw1]

@@AndreasSpiess These were days, when the tubes technology was of centimeters density 😄

[@simonboerboom1620]

It’s like camping: no easy, always working, sophisticated devices; just the curse of simple, difficult to operate tools

[@AndreasSpiess]

Those days the tools were simple, but the skills to use them were bigger. Today 90% of the effort is in UI development to make it easy for the user. And complex for the machine.

[@blacksmock445]

A useful video. I keep receiving e-mails from AliExpress re this type of kit.. Nice to know that it actually works using the supplied valves, unlike some audio amp valve kits, where the valve is just for show and the actual amp is solid-state.

[@AndreasSpiess]

Indeed, this is not a fake valve. Otherwise I would not have shown it...

[@LandNfan]

To get the full flavor of tube technology, you need to build on an aluminum “bread pan” chassis, using point to point wiring. In the early 1970’s, I built my own amateur transmitter from a Heathkit DX-60. Looking back through the haze of all the years, I remember being amazed that it worked on the first try. When I started in amateur radio, it was when novice licenses were first allowed to use variable frequency oscillators. Prior to that our transmitting had to be crystal controlled, or “rock bound” as it was called. I had a lot of fun on 40M CW as WN4BCG.

[@AndreasSpiess]

Things changed considerably over the years and it is a privilege to live in such times, I think. I remember those chassis. But a PCB is of course much easier...

[@valdisblack1541]

I don't know why, but when I see vacuum tube suddenly "Rammstein - Radio" starts playing inside my head ;D

[@AndreasSpiess]

Interesting! I am not sure they were already playing in the "tubes ages" ;-) It probably should be "Beatles" or Elvis"

[@abysspegasusgaming]

Seeing the resurgence of tube tech is enlightening. Pun aside, tube radios sound wonderful compared to the solid state counterparts. I had a 1950's RCA Victor that worked great for as old as it was, unfortunately the tuning band snapped and i couldn't figure out how to repair it, let alone have the high school electronics lab do the repair to it. And I just made myself feel old even though I'm only 35...

[@AndreasSpiess]

This seems more like a mechanical problem... I am sure you will be able to solve it.

[@abysspegasusgaming]

@@AndreasSpiess I'm sure I would be able to had the radio not gotten thrown out by a past step-parent. I had the radio when I was in my teens (acquired roughly 2000-2001). Thanks to a divorce though in 2010, through that I gained at least 150 working vac tubes that I could build my own radio, if not that, at least an amplifier.

[@paulmathison2906]

Thank you Andreas for sharing, a very enjoyable video. Very pleased you got your radio working as well, interesting about the frequency range and hence the tuning difficulty. I haven't been able to check that on mine as I don't have a suitable generator at home, and it does explain why it's so difficult to tune.

[@AndreasSpiess]

Without a signal generator it is probably too difficult. If you are lucky you find a strong station.

[@captainpugwash4100]

They look beautiful at night! Wonderful decoration.

[@newburypi]

I had an old Westinghouse long band, medium band, shortwave receiver (back in the day) with 6 or 7 tubes. It was seldom in its case, and I would listen to radio at night in just the glow of the filament heaters.

[@AndreasSpiess]

The tubes I have unfortunately do not glow a lot. Even if they use quite some current, they are low-power :-( But the big ones definitively are nice to look at.

[@captainpugwash4100]

Dale P. Newbury Gosh, that is almost romantic!

[@newburypi]

@@captainpugwash4100 ha ha! It could have been so, but then she tried to do me in (after I dropped my hand on the top-cap of one of the tubes in the audio amp section).

[@TiptreeJams]

I love old tech like vaccum tubes / valves and so a great overview of the pros and cons of this kit. For me I think the cons outweigh the pros which puts me off buying the kit. A traditional mechanical metal air spaced capacitor would improve the kit but at about $12 for a new one it would up the price of the kit alot. I have previously bought an old valve radio made in the 1950s that requires attention and will be spending time fault finding, buying parts, repairing, and hopefully ending up with a fully working radio in a traditional wooden case.

[@AndreasSpiess]

A specialist like you looks differently at things than a noob like me, I assume. I ordered a bigger capacitor, even with a gear reduction for 23 dollars (used) because I want to try it out. I did not see many other tube kits around these days...

[@goodboiadvsp3297]

Good, I'm gonna need these basics when I start restoring my old Zenith record cabinet

[@AndreasSpiess]

Good luck!

[@joewoodchuck3824]

Tube theory as well as transistor theory were being taught in courses at tech school back in the late 60's. I graduated equipped for both. I'm sure tubes were dropped from curriculum not long after though. I'm still nostalgic about tubes.

[@AndreasSpiess]

You are right. In 1977 it was no more part of my education.

[@I_love_our_planet]

Vacuum Tubes have been used in Nuclear Shelter for a long time, during my Navy Time I had to maintain these until mid of the 90 ;-) The benefit was that Vacuum Tube-based Electronics survive the EMP of a Nuclear Detonation.

[@AndreasSpiess]

That's what the salesmen told the purchasers ;-) For sure they were much more robust than today's equipment. Later they tried to sell NEMP filters for the same purpose. Fortunately, we never needed them.

[@sevenacregreen]

Great video. I am of an age that one of the lab experiments on me EE degree course involved plotting the transfer characteristics of a valve, all open wire on the bench. Also my memories as a youngster of buying a portable valve radio from a jumble sale. The cost of the 1.5v and 90v batteries was not good on my limited pocket money. My parents talked of taking a heater battery to a shop to be recharged. FETs make life much easier.

[@mikegofton1]

I’ve never used valves in any circuit design, although I admit they have a retro charm - FETs with pilot lights. There are audiophiles and guitarists who are convinced valve amplifiers are more ‘musical’, however I’m sceptical. Apparently valves produce more even order harmonic distortion, and this results in a ‘warmer’ tone - I’ve not seen any spectral analysis to verify this though.

[@r1273m]

My grandparents didn't have electricity in their house. For their radio they bought a 90v battery which lasted a long time as the HT only consumed a few mA. The 1.5V valve heaters however were powered by an accumulator. These were glass cased cells that were rechargeable and a guy called round every week and you simply did a swop for a newly charged accumulator. In 1958 they moved into a house with electricity and bought a "battery eliminator" to power the radio from the mains.

[@AndreasSpiess]

Interesting stories! Each time had their solutions. Today they start to talk again about a "sharing economy. It seems history is moving in circles ;-)

[@softdorothy]

Edwin Howard Armstrong was, I suspect, a time traveler. He developed the regenerative receiver - a design that became the absolute standard for all radios of the era. He later topped himself with the superheterodyne receiver and that too then became the standard design for all radios produced since.

[@AndreasSpiess]

Looking what he achieved I would not focus on his dead. He obviously was a brilliant engineer.

[@Spookieham]

Didn't realise you were a fellow licence holder👍 thanks a great video. 73 de VK6HIL

[@AndreasSpiess]

Since 1977... 73 de HB9BLA

[@chrisvanaalst1960]

Andreas, thx for excellent video, you made my day, as I always wanted to build a tube receiver; I've" bought this kit about 2 months agoo and got stuck, I couldn't find any documentation, I figgered out most of the parts & connections, but the variable capacitor was too much ...

[@AndreasSpiess]

So maybe you can finish it now. I ordered a bigger capacitor because I did not like this small one. But it nearly doubled the price of the kit ;-)

[@johnlr1964]

I really enjoyed your video, it was great. I've been into Vacuum tubes all my life thanks to my grandfather who owned a radio shop in the 1930's. I inherited his original equipment that he used. I ordered on of these 3-tube regen kits about ten days ago, it hasn't come in yet. Do you have a link to the better schematic that you found? I think I could use it. Thanks

[@AndreasSpiess]

Hi John, KZbin does not allow links any more. But you can search with Google with these keywords "tube radio diagram 2p2 1b2" . Select "images" and you will find various diagrams.

[@johnlr1964]

@@AndreasSpiess Thank you very much!

[@cheif10thumbs]

Built one of these for my Radio Merit badge in the BSA. 1970

[@AndreasSpiess]

Quite some time since! For sure you were able to hear more stations than today.

[@cheif10thumbs]

@@AndreasSpiess Used to listen to Radio Free Europe, BBC World, School of the Air, Pravda, Tass and of course Voice of America All on AM and Shortwave. We lived on a small island on just below the equator and almost right on the IDL. The skip was crazy!

[@Bristoll170]

Yes, had to shut the eyes and drag out the Morse from years ago. Subscribe wasn't it, but after about eleventeen replays, "Hi you tubers" finally made sense of the dots & dashes. Of course, it might have been several beers being consumed that made it take eleventeen replays :-) I'm going to order one of those kits just for a trip down memory lane. Thanks for the video :-) Cheers Pete'

[@AndreasSpiess]

You are right with the text. And you were not the only who had to repeat the signal. The statistics shows a big increase for that passage ;-)

[@gbotti82]

Thanks again for another great Video with "the swiss accent" ;) Of course you're right about Mr. Carlson informative channel. He's also one of my favorites. If you haven't seen it already, I wanted to recommend KZbin Videos of ElektorDE, where Mr. Van der Veen is talking about "How to build Tube Amplifiers" and what characteristics Tubes have. It was also very satisfying to see this. Unfortunately the Videos are in German. The Videos are from 2016, but especially with Tubes, this does not even matter ;)

[@AndreasSpiess]

Thanks for the link. I understand German, I just do not speak it properly ;-)

[@gbotti82]

@@AndreasSpiessyou'e welcome. I guessed you speak german a little. :D This was intended more for non english speakers ;)

[@doggo7567]

> won't be killed > cool feature

[@apollorobb]

I think if i was going to build this kit id scrap that Circus board and build it point to point wired in a metal chassis with a full power supply and get rid of the batteries . But then again ive worked on tube type equipment for years so im a bit fussy lol . Seems a reasonable kit for education but thats about it .Great video Andreas .

[@AndreasSpiess]

Otherwise I probably never would have tried tubes...

[@ingmarm8858]

Hi Andreas, I'm not sure if anyone else has picked it up but at 5:33 the choke does NOT remove the high frequency components going to the next stage. It is there to isolate the RF/high frequency components from the power supply rail. I.e. it will have a high inductive reactance (aka resistance) to the RF but a very low resistance path for the power supply DC to the tube. If the RFC was not there then all the other stages of the circuit would have the RF superimposed on their signals too. I could be wrong (been a very long time!) but it looks like C4 the 270pF capacitor on the output of the second valve would provide a low impedance path to ground (589 ohms at 1MHz) but allow audio (589k ohms at 1kHz) to pass. This would achieve the filtering your refer to earlier. 73 VK1BGT

[@AndreasSpiess]

You are right. I mixed it up. 73 de HB9BLA

[@jamesdinsmore9022]

My first job in electronics midway through college was at a small mobile radio shop that still serviced 140 MHz commercial radios with 3 tubes in the RF power amplifier. I fondly remember getting hold of the 300 volt b+ and lodging a screw driver into the ceiling. They also had a wicked relay-driven high voltage generator that hummed loudly to convert the vehicle 12 volts to 300 volts. Good times. I have seen similar kits and wondered how feasible they would be.

[@jimharman5748]

That was a "vibrator" power supply

[@AndreasSpiess]

High voltages always kept me away from tubes. But I assume you can learn how to deal with it. But it will be dangerous even if you know how to deal with it. And generating high voltages was for sure more difficult those days. Now we order a "boost" converter for a few bucks and get 400 volts...

[@jordypaulussen7821]

Than you for the information Andreas .

[@AndreasSpiess]

You are welcome!

[@TheEvertw]

About air entering the tube: there are metals inside the tube to catch any oxygen and hydrogen that enter over time or are left from production. This is the silvery layer on the top of most tubes. It is produced by heating a Barium cup (the "Getter") after the tube is sealed. If air enters the tube, this layer will turn white: a visible sign the tube is faulty.

[@AndreasSpiess]

Very good Information. Thank you!

[@jimmiller5891]

I maybe wrong but I thought the getter was to catch the remaining air molecules after the tube was vacuum pumped and sealed. Sorry that sounds contradictory, that is not the intent. What I mean I don't think the getter will do that [catch air molecules for the purpose of keeping the tube alive] afterwards i.e. yes it turns white but it does not help if the tube gets air into the tube over time.

[@TheEvertw]

​@@jimmiller5891 It is, but the barium stays reactive after production so it also catches any oxygen that enters later. "or are left from production" should be read as "after sealing"-activating the getter happens as part of production. Barium won't catch all molecules, just the reactive ones like oxygen, that cause the most problems in tubes.

[@jimmiller5891]

@@TheEvertw Thanks for the clarification. :)

[@notadroid4406]

Is the message? "Send help. I'm not really Swiss, I''m trapped in this basement…"

[@AndreasSpiess]

No :-))

[@hesspet]

Real radios glow in the dark.... :-)

[@AndreasSpiess]

This one unfortunately not. Too low-power :-(

[@hesspet]

@@AndreasSpiess Add some orange LED underneath. Tubes must glow! :-)

[@RESISTAGE]

I learned A LOT. THANK YOU.

[@AndreasSpiess]

You are welcome!

[@Iamalizard]

I am a grandchild, I'm going to do this with my grandfather, thanks for the tutorial.

[@AndreasSpiess]

I am sure he will like this idea!

[@fido139]

I built tube radios as a teenager in the 60's.

[@AndreasSpiess]

So this topic is not new to you. I was probably a little too young to see tubes in my education.

[@pankajroy5124]

Great video on vaccum tube valves. I always wanted video in this topic. As always your videos rock!!!

[@AndreasSpiess]

Thank you!

[@Robert08010]

If you look closely at 8:24, I think the spec sheet does tell you. I see C1 AM (Ant) and C2 AM (Osc). I presume that means C1 is the input side (antenna side) and C2 is the output side towards the Oscilator.

[@AndreasSpiess]

These are two capacitors and obviously used for these two purposes. However, the transistor radios they are or were used are not regen type.

[@kungufupela]

Excelent project! You have a well equipped laboratory there!

[@AndreasSpiess]

Thank you!

[@gene7511]

Great video! I'm saving this in my post-apocalypse reference videos.

[@AndreasSpiess]

You can add my "Mesh communicator" video, too ;-)

[@Paul_VK3HN]

Liked how you used 2000s technology to test 1950s technology, digital spectrum analyser, HackRF SDR. I thought you might take it upstairs and attach a wire so we could hear one of those big European broadcast AM stations. Are there any still on air? 73 Paul VK3HN.

[@AndreasSpiess]

I do not know about all AM stations. But here they are converted to museums. And I assume the same is the case for most European stations. 73 de HB9BLA

[@marklomax242]

Total Respect to you. You make it look so easy. It is a pleasure to learn from your videos.

[@AndreasSpiess]

That is my goal: To make it look easy. Thank you!

[@dieSpinnt]

Thank you for the great video, Mr. Spiess:) But what do you mean with old technology? I'm smiling right now to my left side where my trusty Engl guitar tube power amp resides. To "these tubes work till today": You can achieve a very good seal with glass and heated-strangulation technique. Also most left over gases (oxygen, nitrogen, carbon dioxide and so on) can initially be adsorbed by the tube's getter. If this media is saturated, R.I.P. tube. Oxygen will burn the heating-element/filament through or other gases impair the function of the tube. You are absolutely right with keeping an eye on the tube-specs (RTFM): - Underheating releases oxygen from the oxide layer, which is deposited on the cathode surface and thus reduces the emission of the cathode (poisoning the cathode) - Overheating increases the evaporation rate of metallic barium from the oxide layer, which also reduces the emission. Tubes are great. Not only do they sound warm, they also warm your heart. ... and the tinkering basement:)

[@AndreasSpiess]

Thank you for the additional information! And tubes still seem to have a big fan community.

[@John_Smith__]

Super fun project no doubt! Thanks once again Andreas! Great Video.

[@AndreasSpiess]

Glad you enjoyed it!

[@3rd_Millennium_Engineering]

Wooo HOOoooo! I'm getting ready to build mine as well...

[@AndreasSpiess]

Very good!

[@jmaguilarr]

thx maestro for a fun video

[@AndreasSpiess]

You are welcome!

[@avejst]

Interesting as always. Thanks for sharing 👍😁

[@AndreasSpiess]

You are welcome!

[@Crypt0Crossf1re]

I just had to comment! Thanks it made me laugh when you had said; "I don't know what I'm doing..." line it was so funny! Good one!

[@AndreasSpiess]

And it was true! I had to learn a lot during this video...

[@dz-abouttechnique1849]

Excellent video!

[@AndreasSpiess]

Thank you!

[@crazystuffproduction]

Thank you, this will for sure help someone doing one of these kits down the line! i like the VFO! would love to see one added...

[@AndreasSpiess]

I am not sure if this would be easy with a regen radio. Needs for sure some amplification, I assume.

[@freesaxon6835]

Thanks your video explanation will help iron out any problems 👌🏻👍🏻

[@AndreasSpiess]

:-)

[@timnixon2889]

I am a ham, electronics guy, and software engineer.. Do I remember something about tubes like "dip the grid and peek the plate" or was it the other way 'round? I first learned electronics in the US Coast Guard and we learned vacuum tubes and transistors (This was 1974) and I worked on high power LORAN transmitters

[@AndreasSpiess]

These were the days... BTW: I created a second channel just for HAM radio if you are interested...

[@r1273m]

22.5V Batteries were very common back in the 1960's. They were used extensively in hearing aids and also flash guns.

[@AndreasSpiess]

Good information! I did not know.

[@fumthings]

and in such radio receivers, i am guessing you cannot find one now.

[@hesspet]

Yes but they are hard to find today and really expensive. I've a portable tube tester from the old days and there is a realy big slot for such a power source. I think they put in 4x6V blocks. Not so hard to replace with some modern cells. and a small regulator :-)

[@mannhansen9337]

And 70's. My first universal V/A and ohm meter from 1975 used one. Hioki AS100-D. The battery was available until early 90's. Today I use two A27 batteries and 2 1N4001 diodes in series to drop voltage.

[@TheDunnock]

My homebuilt regenerative radios in the 50-60s used 45v or even 90v batteries ... probably hard to find now!

[@mitchellatta9808]

I built my first 3 tube kit in 1957. A much better experience. Nice case, schematic, and documentation. Mom and dad were not impressed 🤓🤣

[@AndreasSpiess]

I am born in 1957. So you definitively had an advantage back then ;-) These early kits were of a much better quality I think. But probably also more expensive compared with an average income.

[@geoffjones5421]

Also: Sir John Ambrose Fleming (1849-1945) was an English electrical engineer and physicist, known primarily for inventing in 1904 the first vacuum tube. It was also called a thermionic valve, vacuum diode, kenotron, thermionic tube, or Fleming valve.

[@AndreasSpiess]

Thank you. Other Englishmen already mentioned this fact. I was not aware of it :-(

[@GeorgeWMays]

Thanks for an interesting and enjoyable project. It's appreciated.

[@AndreasSpiess]

Glad you enjoyed it!

[@JimSky]

Commenting 2 years later; Did you ever try it with an outdoor antenna and listen to actual stations? Even in a basement, I am surprised you couldn't pick up some stations with a couple of meters of wire (at night , of course). I must admit it takes a lot of patience to use a regenerative receiver of this caliber. BTW, I love your channel.

[@AndreasSpiess]

No, I did not try it outside. I have better rigs ;-) Still, it was a fun project for me.

[@ananthavishnus.u4771]

It is a 300pf Gang capacitor widely used in radio. Now very difficult to get. Nice work 😃

[@AndreasSpiess]

Thank you for the info. It seems the still sell it on AliExpress

[@ananthavishnus.u4771]

@@AndreasSpiess But unfortunately it is very tough to get anything directly from China.

[@ananthavishnus.u4771]

@@AndreasSpiess On watching your video I was taken to the days when I was building a radio receiver. Four years before I tried. At that time this capacitor was not available in the market so I had to go to scrap store to get old radios. I had to teardown most of the radios to get a working gang capacitor. But unfortunately I had the same issues with the capacitor that you faced. I works when I touch the capacitor.

[@erygion]

Thank you Mr. Spiess, great video. Truth be told it would take me a cool 20 mins or so to decode that, I'm envious that you can do all that by ear! That is incredible! How long did it take to master that? A cool Arduino project stores all Morse code letters and numbers in the EEPROM and you type the message in the serial monitor and it blinks the message in Morse code through LEDs, it was fun.

[@AndreasSpiess]

These days you can build morse transmitters as well as receivers. But this is not wat we want, of course ;-) I started to learn it at the age of 16 and then in the army. Afterwards I was a radio operator for the red cross abroad. It took quite some time to learn it.

[@erygion]

@@AndreasSpiess How cool, very admirable. I bet you have some stories. Thank you for your reply 😁

[@pulesjet]

Growing up in the 60-70 times, vacuum tubes were just about finished. I always avoided them not liking the high voltages involved. In the Military I still had to work on some things mostly communications equipment related. Microwave radio and radar was mostly still Tube operated in the 80's. High Power still is today. We've not got there with semiconductors. You have one in your microwave oven today.. Yep it's a Tube.

[@AndreasSpiess]

So we are very similar. I also had tubes in the high power RF transmitters in military service. The rest was already transistors.

[@mannhansen9337]

Same here. Air Traffic Control radars i 1981-82. Take a look here radionerds.com/index.php/AN~MPN-13. The IF strip was built with transistors, 30 MHz. Rectifier diodes (tubes) big as 1.5 L soda bottles.

[@pulesjet]

@@mannhansen9337 Yes Sir, All Traveling wave tubes or Magnatron.

[@pulesjet]

@@mannhansen9337 reflex klystron opened the gate to HIGH Power Microwave.

[@Chriva]

About the oversized resistors; Given their size I suspect they're rated for quite high loads -ie high power dissipation. Better to mount them "free floating" to give them better air cooling and prevent charring of the board :)

[@AndreasSpiess]

They are 1 Mega Ohms...

[@acrodrigues1]

I may try to build the kit whenever they have smd tubes 😁

[@AndreasSpiess]

These are SMD tubes compared with the "normal" tubes back them ;-)

[@mosquitoMKT]

Hello Andreas, your video helps me a lot! I bought the same kit some weeks ago...but till now didnt worked, so Im trying to do another one (solderless version)...but one question I have: your video at 5:39 shows the circuit with "earth" line (down below), so with +1.5V line, and another with + 22.5 or +9~80V line. Ok so far so good. But the upper "minus" source line will make a "short" at the paralell 22 uF electrolytic capacitor and 510ohms resistor if we plug at earth or 0V negative. I have to put this minus line with 9 volts negative? Which are please the purpose of this capacitor and resistor in parallel? Sorry if I complicated the things lol...73s, Daniel...

[@AndreasSpiess]

I do no more remember the details. But I do not see that I needed a negative voltage in my design. Did you do the steps of testing the audio amplifier? Then you should know in which stage the problem is.

[@mickgibson370]

I have built a radio like that that but it used 2 tubes in the 60's.

[@McTroyd]

Did it drop an amplifier stage for the speaker? The first two stages might be adequate if listening via headphone...

[@AndreasSpiess]

I also found several designs in the internet. Three valves are probably better for loudspeakers, as Ted mentioned

[@rohnkd4hct260]

It is a SORRY kit. But you did a great job getting it to work. 73 de KD4HCT

[@AndreasSpiess]

The live is too easy otherwise... It is also not too expensive, I think. European kits are better quality but more expensive.

[@tobiwonkanogy2975]

RTFM indeed. smart advice for any confused being

[@AndreasSpiess]

:-)