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Author Topic: Help with making a Valve radio  (Read 17566 times)
m1tch
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« on: March 08, 2010, 10:34:54 pm »

Hi everyone, I have a sudden urge to build a valve radio with a proper valve rather than those fake valve style radios, I have seen a few Ipod speaker setups with proper valves to give a much warmer sound than a digital system:



Can anyone point me in the direction of a kit (I have seen a Gaken kit but its quite a bit) or some schematics, I would like to learn how it all works and want to build it myself Smiley

I will make my own case etc and do all the wiring, it would be a good project as I will learn woodworking and electronic skills, plus I will have an awesome item at the end.

Can anyone help?
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JingleJoe
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« Reply #1 on: March 08, 2010, 10:37:00 pm »

Today I tried to make an audio amplifier but it went wrong and turned into a radio Huh
My advice: Try to byuild an amplifier and fail.

P.S. There's definately circuit diagrams out there if you find any yourself post here please Smiley
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m1tch
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« Reply #2 on: March 08, 2010, 10:56:10 pm »

The issue being that the older radios ran off a 90V battery, I could get an old school one and get a battery replacement kit so I can plug it into the mains, there are kits using printed circuit boards that run on 12V.

How cool would it be if I got a model steam engine, that ran a generator that then ran a low power valve radio Cheesy
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JingleJoe
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« Reply #3 on: March 08, 2010, 11:00:40 pm »

How cool would it be if I got a model steam engine, that ran a generator that then ran a low power valve radio Cheesy
Entirely possible but you need a decent size steam engine and a good pressure of steam to turn anything (as my experiments with my own model steam engine showed me Roll Eyes)

It is not hard to get a transformer to bring your voltage down to roughly the required level, however making it DC and making it sustain an even flow requires some voltage regulator circuitry which I am only familiar with for low voltage aplications.
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The Inventor
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« Reply #4 on: March 09, 2010, 04:55:48 am »

That would be amazing !
And well beyond my current set of skills, making circuit boards and such...
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Drew P
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« Reply #5 on: March 09, 2010, 05:49:12 am »

The latest issue of 'AudioXpress' has a good amp to try w/schematic + parts lists. Point to point wiring,no boards(the good way). Although,it doesn't state the total $$ for parts. But it probably beats the $$$ for a built one by far.  mmmmmmmmmmmm...high voltages.
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Satanic Mechanic
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« Reply #6 on: March 09, 2010, 05:50:28 pm »

M1tch,
I do not know your level of electronics knowledge but may I suggest you purchase an unused Heathkit vacuum tube radio kit?  There are some out there and the Heathkits usually are educational for beginners.  There are schematics out there if you know electronics. 
You will find it fun to work on tubes.  Myself and another engineer debated last week about the true definition of "plate neutralization" in tubes.  If you need some tubes, drop me an email, I'll check my collection and send you a couple.  It is more fun to homebrew the project in my opinion.

SM
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m1tch
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« Reply #7 on: March 09, 2010, 08:10:13 pm »

I have found a kit like this for about £40



It will let me use my own case etc which is good, but whilst searching for things I came across this site:

http://www.mds975.co.uk/Content/trfradios05.html

There is a schematic (seeming easy to make as there is a photo of one made) on that page, its also 12V so I won't get electrocuted when I mess up lol will probably just burn myself on the tube! lol

@satanic mechanic

thank you so much for the offer, it seems that valves (to be more precise the correct valves) are quite hard to come by especially the ones that actually work! I might have to ask you for some help if I can't find what I need!

I am rather new to electronics, I have done physics at A level, but I did cosmology, so slightly bigger than circuit boards! I am looking for a nice cool retro look with exposed workings and the warm sound of the valve Smiley

My mate is into electronics, he can basically find a problem and then just solder together a perfect solution in no time at all lol wish I was that good!

I will start looking at getting some parts together, where would be the best place to start? or should I find a broken radio and try and repair that?

I have seen quite a few 'retro' designs of modern radios with light up valves lol I don't like them as I know they are fake, so the real retro valve radios are what I am after as everything is too enclosed, I will be aiming for something like this (only not fake and less plastiky!):



Gotta get me a valve amplifer Cheesy

One valve radioDQ
« Last Edit: March 09, 2010, 08:23:22 pm by m1tch » Logged
Don Tragos
Guest
« Reply #8 on: March 09, 2010, 08:44:18 pm »

Here are a few sites that may help.

Nostalgia Air

Steve’s Antique Technology

Stay Tuned



And while they are not about valve radios in particular, I recommend these two books, they are great for inspiration.

Voice of the Crystal
Instruments of Amplification

« Last Edit: March 09, 2010, 09:28:20 pm by Don Tragos » Logged
Satanic Mechanic
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« Reply #9 on: March 10, 2010, 12:27:50 am »

thank you so much for the offer, it seems that valves (to be more precise the correct valves) are quite hard to come by especially the ones that actually work! I might have to ask you for some help if I can't find what I need!

Might I suggest a website to look at:http://www.nj7p.org/Tube.php.  This website is great to find equivalent tubes.  My friend, who is a vacuum tube audiophile, showed this to me and saved me a lot of money.  One tube I could not find had over twenty equivalents and I managed to find some of them.

SM
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chainmailleman
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« Reply #10 on: March 10, 2010, 06:12:51 am »

Here's a schematic of a 1 tube radio if you want to make it yourself.
Spoiler (click to show/hide)
D1 is a diode tube. The rest is pretty much self explanatory.
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KJ6GOT
m1tch
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« Reply #11 on: March 10, 2010, 12:16:35 pm »

Thanks so much for that schematic, what power does that need to run?
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chainmailleman
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« Reply #12 on: March 10, 2010, 03:48:16 pm »

Thanks so much for that schematic, what power does that need to run?

Whatever you want. All depends on the valve used. For example a 12ax7 will run at 12 volts and a 6l6 will run at 6 volts. The voltage rating is for the filament, which is the first number. You can use any tube so long as you have one cathode and one anode (connect all the plates to the anode with triodes, pentodes, tetrodes, etc.) 

Also, the schematic listed does not specify headphones. If you use crystal phones, you don't use C2. If you use conventional headphones you don't use R1.
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chainmailleman
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« Reply #13 on: March 10, 2010, 03:55:13 pm »

Correction: You can use any random tube so long as all the grids are connected to the anode.
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m1tch
Gunner
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United Kingdom United Kingdom


« Reply #14 on: March 10, 2010, 05:02:24 pm »

Sorry for such a novice question, but is a diode tube the same as a vacuum tube/valve?

I have seen on the Heathkit magiceye radios (the cool ones that glow and pulse green) are a diode tube, would it work with that schematic? Is there any part of the circuit I can use a ?reactive capacitor? it sharpens up the valve to give a better output - one is tuning, one sharpens up the signal, its on one of the youtube videos above (its the one connected to the valve amplifier).

What are the benfits of having a 2, 3 or 4 valve set?

I have just found the schematic with the values of each of the parts on oddmix.com:

http://www.oddmix.com/tech/cr_vacuum_tube_detector_radio.html

seems much easier Cheesy
« Last Edit: March 10, 2010, 05:23:40 pm by m1tch » Logged
chainmailleman
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United States United States


« Reply #15 on: March 10, 2010, 06:37:47 pm »

Asking questions is the only way to learn.

Do you mean reactive power? For I admit I have never heard of a reactive capacitor before.

A "Diode Tube" is short for a vacuum tube diode. A diode only allows the flow of charge to move in one direction but not the other (within it's breakdown voltage, but thats with solid state devices and are not a problem with thermionic valves). A detector is a diode.

Those schematics call for a 1.5 volt diode. Which is what any single disposable battery will produce. But since 1.5v tubes are rare, I recommend 6l6gc tubes. 1.00 a pop on ebay.

Just listen to a multi-valve radio vs. a single valve radio. You'll understand almost instantly. It's the difference between night and day.

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chainmailleman
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United States United States


« Reply #16 on: March 10, 2010, 06:50:06 pm »

A little about tubes.

Diodes have 2 electrodes, cathode and anode
Triodes have 3 electrodes, cathode, anode, grid.
Tetrode, pentode, ect. Have 4+ electrodes and have multiple grids.

All vacuum tubes can be used as a diode, as a diode has the lowest number of electrodes needed to make a thermionic valve.

To understand the tube, is to understand the transistor. And then you have understood modern electronics.

Check this out, it might help out some. http://amasci.com/amateur/transis.html
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m1tch
Gunner
**
United Kingdom United Kingdom


« Reply #17 on: March 10, 2010, 06:57:15 pm »

Asking questions is the only way to learn.

Do you mean reactive power? For I admit I have never heard of a reactive capacitor before.

A "Diode Tube" is short for a vacuum tube diode. A diode only allows the flow of charge to move in one direction but not the other (within it's breakdown voltage, but thats with solid state devices and are not a problem with thermionic valves). A detector is a diode.

Those schematics call for a 1.5 volt diode. Which is what any single disposable battery will produce. But since 1.5v tubes are rare, I recommend 6l6gc tubes. 1.00 a pop on ebay.

Just listen to a multi-valve radio vs. a single valve radio. You'll understand almost instantly. It's the difference between night and day.




I just replayed the video above, its uses a 1T4 tube, and also has a reaction capacitor, this is noted at 0:57 of the video, im not quite sure what that might be, but it does make quite a difference to very fine tune the output.

I will have a look for some 6l6gc tubes on ebay, I am in the UK so I don't know how easy they are to get hold of, but I will have a look around Smiley

I think I will start out with a 1 valve radio, something like this armstrong 1 valve radio:



Looks quite neat and easy to make, whats more everything is exposed which is what I want to go for.
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chainmailleman
Deck Hand
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United States United States


« Reply #18 on: March 10, 2010, 09:16:36 pm »

Yeah, if you can get low voltage tubes, snag em'. It's so worth it. Tubes are fun to play with.

I'll have to look into a reactive capacitor. Google shames me today.
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Satanic Mechanic
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« Reply #19 on: March 10, 2010, 09:35:08 pm »

I'll have to look into a reactive capacitor. Google shames me today.
I think he is talking about the tuning capacitor in the LC circuit.

SM
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m1tch
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United Kingdom United Kingdom


« Reply #20 on: March 10, 2010, 11:38:12 pm »

It seems that on that 1 valve radio in the video there is:

on/off switch
variable capacitor for tuning in the station
'reactive' capaciter for sharpening the valve up

On the schematic above from oddmix it has just an on/off switch and a tuning capaciter for tuning in the station.

I will ask my mate who did seem to know about reactive capacitors when I mentioned it so I will ask about it, I just had a look for a 6l6gc tube on ebay, they are retailing for about £6.50, so thats about $10 each Sad is that about right?
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Khem Caigan
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« Reply #21 on: March 11, 2010, 01:07:05 am »

Hi everyone, I have a sudden urge to build a valve radio with a proper valve rather than those fake valve style radios. . .
Can anyone point me in the direction of a kit (I have seen a Gaken kit but its quite a bit) or some schematics, I would like to learn how it all works and want to build it myself Smiley

Here are a couple of old posts with
lots of links to get you started :

Re: Period Electronics
« Reply #2 on: June 01, 2009 »
http://tinyurl.com/yb3gocx

    
Re: Steam Powered Radio
« Reply #14 on: May 19, 2009 »
http://tinyurl.com/ydeht8h
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Satanic Mechanic
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United States Minor Outlying Islands United States Minor Outlying Islands



« Reply #22 on: March 11, 2010, 01:23:13 am »

It seems that on that 1 valve radio in the video there is:

on/off switch
variable capacitor for tuning in the station
'reactive' capaciter for sharpening the valve up

On the schematic above from oddmix it has just an on/off switch and a tuning capaciter for tuning in the station.

I will ask my mate who did seem to know about reactive capacitors when I mentioned it so I will ask about it, I just had a look for a 6l6gc tube on ebay, they are retailing for about £6.50, so thats about $10 each Sad is that about right?
OK, you are talking about a regenerative receiver.  Your term "reactive" is called "grid leak".
$10 for a 6L6gc... that is a bit much.  At that price, there should be two, be brand new and tested.    Is this a local source or by mail?

SM

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chainmailleman
Deck Hand
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United States United States


« Reply #23 on: March 11, 2010, 07:06:58 am »

It seems that on that 1 valve radio in the video there is:

on/off switch
variable capacitor for tuning in the station
'reactive' capaciter for sharpening the valve up

On the schematic above from oddmix it has just an on/off switch and a tuning capaciter for tuning in the station.

I will ask my mate who did seem to know about reactive capacitors when I mentioned it so I will ask about it, I just had a look for a 6l6gc tube on ebay, they are retailing for about £6.50, so thats about $10 each Sad is that about right?
OK, you are talking about a regenerative receiver.  Your term "reactive" is called "grid leak".
$10 for a 6L6gc... that is a bit much.  At that price, there should be two, be brand new and tested.    Is this a local source or by mail?

SM



That clears up everything. Thanks for pointing that out SM.

I agree, that should be a package of at least 2, tested, and shipped to your door for that price.
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Mr.Surly
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United States United States


« Reply #24 on: March 12, 2010, 04:02:42 am »

I've done some work with tube equipment before.  It's important to note that many tube-based circuits require 150VDC to 350VDC or more, and have large ripple capacitors that can store a charge for a considerable time.

I've worked on a *lot* of electronics.  I won't hesitate to stick my hands into a 5, 12, or 24V circuit, but I'm very careful with the tube stuff, as it's much higher voltage, and they're often wired in a terminal post open frame manner that means a lot of potential places to come in contact with something lethal.
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