Vintage Radio Electronics

[total-recoil]

I recently got into radio electronics although I had been dabbling in basic electronics before I specialised in radio. After doing a bit on transistors, I decided to go back in time to the old tube or valve sets and came to see there is a large network of hobbyists online in all countries. Such people enjoy picking up old tube radios and getting them to work again. I have a book devoted to tube radios which apparently has had a fairly bad review as it does contain a few unpardonable errors. People have referred to misprints and spelling mistakes but I also think I found a few tiny circuit diagram errors. However, the book is helping me learn a lot more and is still quite useful.
What you need to think about with this hobby is these radios have a real history. Some would have been used during the war. I have one that's a very early transistor set, made in 1960.
I often wonder why I would want to learn old technology anyway as I seriously doubt I'd make any money fixing up broken tube radios (assuming I get to the stage of actual service). I guess it's just interesting.
I think the best way for me to start really would be to buy a DIY transistor radio kit and just make a radio up, following the instructions. That way I can get the hang of soldering circuits again. Later on maybe start to test valve sets and detect what components need to be replaced and so on.
For anyone who may be interested, valves or tubes basically worked as diodes or amplifiers. They were used to detect signals and amplify signals but the big drawback was that power demand was high so most tube sets were 240 volt supply. Now with tiny silicon transitors which act just like valves all you need is a 6 or 9 volt supply.

 

[smith2267]

Yes this sort of thing is interesting. I got into it a bit when I was young

 

[Nolan1971]

I love old tech like tube radio's! I started with crystal/transistor radio kits when I was 4yrs old. I later started modifying store bought electronics at 5 installing better speakers or adding more of them. Some of the tube or early transistor amps had cleaner sound with far less distortion than the average stuff does today.
One high-power tube amp radio shack used to sell had only .002% distortion while most today are around 10%.

 

[total-recoil]

I'm currently on TRF thirties tube radios as I'm taking my time. The book I have has been criticized a bit for mistakes or rushing ahead at too fast a pace but I'm still finding it useful and I throw in electronics books as well. I find if I don't supplement with electronics theory as well, I tend to get rusty over basics.
So, I've covered early stuff such as grid leak circuits and backfeed. The TRF tube radios usually have 3 tubes, one for amplification of tjhe signal, one as a detector and the final tube again amplifies the audio output. So, I haven't yet tackled superhets.
Pity that the exclusive study of vintage radio is highly unlikely to make me any money and I guess at the antique sales I go to they'd have trouble giving sets away. I was recently informed there are virtually no experts on vintage radio in this country that have actually written any books so the majority of books come from the U.S.A. However, the other night I found an actual university in the Ukraine that takes radio technology students from abroad.

I love old tech like tube radio's! I started with crystal/transistor radio kits when I was 4yrs old. I later started modifying store bought electronics at 5 installing better speakers or adding more of them. Some of the tube or early transistor amps had cleaner sound with far less distortion than the average stuff does today.
One high-power tube amp radio shack used to sell had only .002% distortion while most today are around 10%.

 

[Nolan1971]

From what I see the popularity of tube & other older electronics is going up at least for nostalgic reasons.
The demand for turntables is going way up with record companies releasing vinyl again and since nobody makes turntables
anymore there are few to be found. There may not be a high demand for repair of the old stuff but that might change.

 

[wyverary]

From what I see the popularity of tube & other older electronics is going up at least for nostalgic reasons.
The demand for turntables is going way up with record companies releasing vinyl again and since nobody makes turntables
anymore there are few to be found. There may not be a high demand for repair of the old stuff but that might change.

As far as vacuum-tube components go, it's not just nostalgia. I first heard an entirely tube-based stereo setup a few months ago, and the difference between tube-powered gear and more modern solid-state components is startling. There are those who prefer one over the other, but for me, I fell in love with how *smooth* the tube sound was - they aren't quite as detailed as some digital or solid-state gear, but it is a lush, full sound, with a beautiful midrange and a nice hefty low end - a word I hear a lot that I think is accurate is "enveloping." The tube CD player sounded amazing, but the turntable sounded even better - I think I finally get why "analog" is still highly-prized among audiophiles. I can't wait till I can afford to buy my own tube gear!

And yes, there is a demand for repair - this same person recently sent his amp off to get new tubes, and it's great.

 

[Nolan1971]

I remember when I was 6 my mom still had a old furniture style tube system AM/FM, turntable & 8 track.
I would love to find something close even a seperate component system.
One feature I miss on a good turntable was the pitch control so I could slow down a track

 

[Nolan1971]

This is alot like the stereo I remember it has 2 amps one for the 4 speakers in the cabinet and the other for external speakers.

 

[total-recoil]

There is still a demand for sound system tubes although vintage radio is still only a minority interest. For the moment my interest is just vintage radio but perhaps later I could expand somewhat.
For anyone following this who may not know how tubes (or valves) work, I'll describe the basic theory. Essentially, the most usual tube is called a triode because it has 3 terminals. The first is the filament. Second is the grid. Third is the anode. It works very simply. The battery powered thirties radios I'm now studying had one battery called an L.T. battery that heated the filament in the tube. This heat creates a cloud of electrons around the filament. A very low powered battery called the G.B. battery is connected to the grid, the purpose being to hold the grid close to 0 volts but still at negative potential. In fact it acts just like a transistor gate. The final terminal is the anode which is positive and connects to a 90 volt H.T. battery. Now, here's the essential part: The negative electrons that emerge from the heated filament of the valve immediately are head towards the positive anode of the valve but the grid regulates this flow. If the grid becomes more positive, the electrons flow straight through in a strong current towards and out of the anode into the circuit. However, if the grid becomes too negative, electrons cannot pass the grid at all and are repelled back to the filament. Thus what we have is a diode. The filament is the cathode and the anode of the valve is positive. Current can flow through the valve only one way so any reverse battery connection would kill the circuit.
In all of this, the grid is the most important. The potential of the grid has to be spot on so current can pass through it but it also tends to oscillate due to slight changes in grid potential.
Valve technology goes way beyond this simple summary but, when all is said and done, valves are just high powered transistors in principle. There were all sorts of problems encountered with them so new valves such as tetrodes and pentodes evolved in labs in order to try and improve efficiency of the radio.
All I described so far is kind of dated as I'm still on battery powered sets of the thirties but very soon I'll be going onto mains and maybe in a few weeks Superheterodyne sets.

As far as vacuum-tube components go, it's not just nostalgia. I first heard an entirely tube-based stereo setup a few months ago, and the difference between tube-powered gear and more modern solid-state components is startling. There are those who prefer one over the other, but for me, I fell in love with how *smooth* the tube sound was - they aren't quite as detailed as some digital or solid-state gear, but it is a lush, full sound, with a beautiful midrange and a nice hefty low end - a word I hear a lot that I think is accurate is "enveloping." The tube CD player sounded amazing, but the turntable sounded even better - I think I finally get why "analog" is still highly-prized among audiophiles. I can't wait till I can afford to buy my own tube gear!

And yes, there is a demand for repair - this same person recently sent his amp off to get new tubes, and it's great.

 

[wyverary]

This awesome. I wish I could hang out in your workshop so I could watch you work and pick your brain!

 

[Vulcanel]

I don't like to call it obsession but maybe it is. I am the same way about tube sets and there was a time when I would go on eBay and just buy old tube sockets and tubes and I amassed quite a collection. I picked up a 500W linear amplifier and repaired it, changed out the power supply capacitors. Once it was fixed I tested it and after ascertaining it was working just fine, it has now sat on my shelf for 6 years, although I look at it every day. Then I found another one at a radio fest but it was linear amplifier for a CB radio but has tubes in it. I finally hunted down the power transistors (yes it has both tubes and transistors) and got it working (runs on 12 volts) and it is on the shelf now too. I learned quite a bit about all sorts of things radio, Edwin Armstrong and his battles with his old friend the CEO of RCA back in the day, tons of info. I still become emotional when I think about Edwin Armstrong walking off like he did and the circumstances he had to deal with, highly suspect he was an Asper

 

[total-recoil]

I don't like to call it obsession but maybe it is. I am the same way about tube sets and there was a time when I would go on eBay and just buy old tube sockets and tubes and I amassed quite a collection. I picked up a 500W linear amplifier and repaired it, changed out the power supply capacitors. Once it was fixed I tested it and after ascertaining it was working just fine, it has now sat on my shelf for 6 years, although I look at it every day. Then I found another one at a radio fest but it was linear amplifier for a CB radio but has tubes in it. I finally hunted down the power transistors (yes it has both tubes and transistors) and got it working (runs on 12 volts) and it is on the shelf now too. I learned quite a bit about all sorts of things radio, Edwin Armstrong and his battles with his old friend the CEO of RCA back in the day, tons of info. I still become emotional when I think about Edwin Armstrong walking off like he did and the circumstances he had to deal with, highly suspect he was an Asper

I'm still hard at it although now I work long hours there is less time. I've been having issues with radio waves or (better said) radio signals. In former times these were sent out via valves at lower frequencies on the Kilohertz scale. Problem I always have is conventional books don't explain in enough detail things I really need to understand. Seems better to me always to tackle the basics over and over again and the issue that I find confusing is usually voltage in relation to current. With tubes, voltage directed at the grid has a direct effect on the anode current and they call this a curve. In the older vintage radios the grid had to be biased by a specific battery called the Grid Bias battery and strangely enough this was somewhere around the negative scale. The reason voltage is so important is because radio waves are basically A.C. signals and the fact they arrive at a radio detector at alternating frequency has a huge impact on coils and capacitors. Evidently capacitors act almost like a resistor at lower frequencies and coils can only be used as transformers if there is an alternating voltage.
At the moment I've gone back to revise the basic principles of batteries, magnetism, coils and A.C, generators.

 

[total-recoil]

This awesome. I wish I could hang out in your workshop so I could watch you work and pick your brain!

I'm only on theory at the moment. Actual repair of a vintage radio is something that will come later. i was thinking my best bet for now might be to buy a DIY transistor radio kit and solder up a ready made printed circuit. Of course, these are not valves but it would be a beginning. Funny thing is transistors are really just the same as valves but far less voltage required. I did delve into transistors a bit - the different types.

 

[Vulcanel]

I'm still hard at it although now I work long hours there is less time....

Oh you're going to love this:

SWRadio

If you go to the link in the last sentence of the first paragraph where it links to the Cenco catalog for the thing, if you can read through it then it will advance you quite a bit !!

))

 

[total-recoil]

Oh you're going to love this:

SWRadio

If you go to the link in the last sentence of the first paragraph where it links to the Cenco catalog for the thing, if you can read through it then it will advance you quite a bit !!

))

I'm currently a bit stuck on something. Apparently the twenties and thirties tube radios called TRF radios had multiple coils on one former. So, one former could have a LW and MW coil and be called primary and the secondary could also consist two coils. Where I get foxed is how the switch selects a waveband. My book reprints a diagram that shows the switches and merely adds, "switch one shorts out LW to enable MW." All I can see in the diagram is the switch connected to the upper part of the coil which, when flicked, runs to chassis. Problem is no more explanation is given. This happens a lot in books - you seek more detailed information but it's left as it is. Anyway, TRF radios had push buttons that allowed bands to be selected so inside the radio were several coils. I'm told TRF's have made a comeback using transistors instead of valves.

 

[total-recoil]

Presently delving into rectifiers. Quite a complex topic really which I think needs an understanding of magnetic fields as a preliminary. As many of us know, AC electrical supply is alterntaing current in the form of a sine wave and not suitable to power radios, DVD players or P.C. circuits directly. For this, A.C. has to be stepped down and rectified to D.C. What I find is in the old days vintage radios again used valves to rectify alternating current. By placing a valve in a coil circuit, only the positive pulses of an A.C. supply can pass the diode valve into the circuit(not negative cycles) (half wave rectification) but sometimes two diodes were used for the full wave rectification. Other coils called chokes were used to chop the sine waves to eventually get a fairly steady D.C. current.
However, it's a bit more complicated than this and I struggle to find a book that really explains all the angles. For some reason nobody ever explains it from the very beginning (which goes back to magnetic fields and coil induction).

 

[total-recoil]

This is still ongoing. I spent a bit of time revising and am now doing superhet valves for the first time. It's now getting a lot more difficult since superhet valves have what's called oscillators. Where I'm struggling a bit is the writer keeps printing diagrams he doesn't fully label so I struggle to make sense of any quoted superhet circuits.
The part before this on mains valve radios was interesting for me as it shows how valves were also used to convert AC mains to DC. Apparently the positive cycle of an AC sine wave was directed at the valve anode and emerged as a pulse at the valve cathode. Tbis was single wave rectification. Two valves (or a diode bridge) was used for full wave rectification.
Anyway, I am still going ahead and hopefully at some point in time I'll find an old clapped out valve radio and hopefully service it so it works again.

 

[The Penguin]

This is a very interesting post. When I was in Sweden, my gf took me to the Radio Museum. I got a chance to learn allot of older technology. My gf also spotted a few postcards from Canada. I have attached one of the pictures I taken when I was there