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Advantages to using vacuum tubes?

KB1WKI

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Dec 3, 2011
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I got licensed fairly recently. One of the reasons I got licensed is because I enjoy making
electronics and wanted to experiment with RF.

I was looking at some DIY linear amplifier projects and a lot of them seem to be based around
vacuum tubes instead of modern transistors. Are there advantages to using vacuum tubes or is more of a novelty sort of thing?
 

W5LZ

Crotchety Old Bastard
Apr 8, 2005
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I would think that the type of device (tube/transistor) used would be determined by the type of primary power you have available, AC or DC. If you are talking about an amplifier that has AC power available, say at home, then the high voltages required by tubes is easier/cheaper to make than the low voltage but high current required for transistors. the opposite is true for where DC is available, say in a vehicle. Then it's a matter of the power desired, a single tube is capable of producing much more power than a single transistor. (That depends on the tube and transistor of course.)
It makes more sense to me to use tubes when talking about an amplifier at home. It makes more sense to me to use transistors if there's no AC available.
'New' or 'old fashioned' has little to do with it other than for availability. What about heat production? So what, both produce heat, deal with it. What about the other 'bad' characteristics of tubes or transistors? Same answer, deal with them. Both devices have been around long enough that the 'how' of dealing with those characteristics are fairly common. Size? Tube type amplifiers are generally larger in size than transistor amplifiers. What's so unusual about that, make room for whichever you decide on. If you are limited to very small spaces to put an amplifier then a transistor type should do okay, but in a fixed location you still have to figure the room for a rather large power supply. Use which ever suits your situation the best/easiest.
- 'Doc
 
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Captain Kilowatt

Professional Amateur
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Apr 6, 2005
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Doc is pretty much right on. It is far easier to build a power supply that will deliver high voltage at low current than it is to build a low voltage high current supply. The basic amplifier circuit of a tube amp is also much simpler especially when dealing with high power.Unless you want to get into some pretty high tech and expensive solidstate components it is easier to develop several hundred or even a thousand watts from a single tube than from a single solidstate component. Beside all that tubes look much better in the daylight and especially in the dark. ;)
 

KB1WKI

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Hmm, I might want to start playing with vacuum tubes.
Working with high voltages scare me though and its not
like something I can plop on my breadboard :p

Do you guys have any sort of introductory literature to getting
started with working with tubes that you would recommend.

Also, where the hell do I buy them?
 

Beetle

Sr. Member
Dec 7, 2005
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Are there advantages to using vacuum tubes or is more of a novelty sort of thing?

Since vacuum tubes were around for a LOOONG time before solid state equipment popped up, the "novelty" is not with them. "Novelty", implying "new", describes these upstart "tran-ZIS-ters" and DYE-odes and such. :D
 

KB1WKI

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Since vacuum tubes were around for a LOOONG time before solid state equipment popped up, the "novelty" is not with them. "Novelty", implying "new", describes these upstart "tran-ZIS-ters" and DYE-odes and such. :D

Well I figured that possibly because they are not used anymore that perhaps it was a novelty for a project being built around old technology.

Anyway, looking at some circuits they do seem to be very simple compared to a transistor equivalent. I'm assuming its harder to burn out vs a transistor too?
 

W5LZ

Crotchety Old Bastard
Apr 8, 2005
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The idea that tubes aren't around anymore is slightly exaggerated. They certainly are around and not rare by any means. Of course, that depends on the kind of tube. Typical 'transmitting' tubes can be had in a lot of different places.
Before I got too enthused about building an amplifier I think it would be a very good idea to know how they work, not just how they are put together. As for 'breadboarding' an amplifier, that's how most of them came about to start with. That does assume you are smart enough, and careful enough not to kill yourself when doing that. Them things definitely will 'bite' you if they get half a chance. If you aren't 'cautious' (meaning you ain't 'frad'a no voltages) pay up your insurance before starting. (Dam right I'm afraid of high voltage! I've seen what it can do.)
- 'Doc
 
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KB1WKI

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That does assume you are smart enough, and careful enough not to kill yourself when doing that. Them things definitely will 'bite' you if they get half a chance.

That's my primary concern with messing with them, I have no experience with working with high voltages! But as long as I don't make myself a path to ground and check, check, and recheck my wiring I think I could manage not to kill myself :unsure:

Where do you find them? I am assuming not all tubes are the same? I was going to try to hit up my local antique shop and buy an old cheap tube radio and grab tubes out of that?
 

W5LZ

Crotchety Old Bastard
Apr 8, 2005
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I think before you run out and buy up a few dozen tubes that you find out how they work and why. Then you get to find out why/how they are constructed, how many elements and what kind are in them and why. There are I-dont-know-how-many different kinds of tubes, each serve a particular purpose.
Safety. The simple answer is just don't touch nothing! Only touch things with one hand in your -back- pocket! You can inadvertently 'grab' something in that front pocket that will really hurt (involuntary muscle contractions you know). You can boil all that down to do a lot of thinking -before- doing/touching stuff. Dealing with high voltages is not simple, and safety is a relative term in that respect. If you don't know what you are doing, then don't do it.
Have fun... carefully! :)
- 'Doc
 

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