Yes, I know it sounds like a stupid question. And maybe it should be
stated as "How do tubes get hot?"

But, think about it: tubes are full of vacuum. Vacuum is an excellent
insulator. What makes the glass hot?

The only think I can think of is that the internal components must radiate
a lot of infrared light (which, by black body theory, means they must be
really hot), and the glass envelopes absorb it.

Does anyone here know what actually happens?

/kenw
Ken Wallewein
K&M Systems Integration
Phone (403)274-7848
Fax (403)275-4535

www.kmsi.net

You already answered, plain glass is partially "black" to IR.

Ciao

Fabio
ha scritto nel messaggio
...
Yes, I know it sounds like a stupid question. And maybe it should be
stated as "How do tubes get hot?"

But, think about it: tubes are full of vacuum. Vacuum is an excellent
insulator. What makes the glass hot?

The only think I can think of is that the internal components must radiate
a lot of infrared light (which, by black body theory, means they must be
really hot), and the glass envelopes absorb it.

Does anyone here know what actually happens?

/kenw
Ken Wallewein
K&M Systems Integration
Phone (403)274-7848
Fax (403)275-4535

www.kmsi.net

wrote:

Yes, I know it sounds like a stupid question. And maybe it should be
stated as "How do tubes get hot?"

But, think about it: tubes are full of vacuum. Vacuum is an excellent
insulator. What makes the glass hot?

The only think I can think of is that the internal components must radiate
a lot of infrared light (which, by black body theory, means they must be
really hot), and the glass envelopes absorb it.

Does anyone here know what actually happens?

It is indeed the infrared radiation. Same as a light bulb.

Graham

wrote:
Yes, I know it sounds like a stupid question. And maybe it should be
stated as "How do tubes get hot?"

But, think about it: tubes are full of vacuum. Vacuum is an excellent
insulator. What makes the glass hot?

Thermal conduction, the conduction of heat through metal
elements of the tube such as the pins. There is never an absolute
vacuum in a tube, there is always a small amount of gas left in the
tube from manufacturing and as a tube is used more gas is released.

Surf my site: http://www.RetroTech.ca

Thermal conduction,


** ROTFLMAO !!



the conduction of heat through metal
elements of the tube such as the pins.


** Wacky !!!


There is never an absolute
vacuum in a tube,


** Really?

News to all those dumb electrons.



there is always a small amount of gas left in the
tube from manufacturing and as a tube is used more gas is released.


** Rocket scientist - no doubt.



.......... Phil

wrote:
Yes, I know it sounds like a stupid question. And maybe it should be
stated as "How do tubes get hot?"

But, think about it: tubes are full of vacuum. Vacuum is an excellent
insulator. What makes the glass hot?

The only think I can think of is that the internal components must radiate
a lot of infrared light (which, by black body theory, means they must be
really hot), and the glass envelopes absorb it.

Does anyone here know what actually happens?

/kenw
Ken Wallewein
K&M Systems Integration
Phone (403)274-7848
Fax (403)275-4535

www.kmsi.net

In article .com,
says...


wrote:
Yes, I know it sounds like a stupid question. And maybe it should be
stated as "How do tubes get hot?"

But, think about it: tubes are full of vacuum. Vacuum is an excellent
insulator. What makes the glass hot?

Thermal conduction, the conduction of heat through metal
elements of the tube such as the pins. There is never an absolute
vacuum in a tube, there is always a small amount of gas left in the
tube from manufacturing and as a tube is used more gas is released.

Surf my site: http://www.RetroTech.ca


There is no problem with heat being radiated through a vacuum.
Consider the Sun....

Don wrote:

In article .com,
says...


wrote:
Yes, I know it sounds like a stupid question. And maybe it should be
stated as "How do tubes get hot?"

But, think about it: tubes are full of vacuum. Vacuum is an excellent
insulator. What makes the glass hot?

Thermal conduction, the conduction of heat through metal
elements of the tube such as the pins. There is never an absolute
vacuum in a tube, there is always a small amount of gas left in the
tube from manufacturing and as a tube is used more gas is released.

Surf my site: http://www.RetroTech.ca


There is no problem with heat being radiated through a vacuum.
Consider the Sun....

The tube has a hot cathode and anode, and both conduct some heat
down the support rods to the glass, so it warms up, but the majority
of glass heating is because the heat radiating through the glass is partially
absorbed
so the glass gets hot.

And yes there is always some gas in any tube.
The gettering process is continuous through the tube's life,
and it is constantly absorbing atoms of gas.

Nothing is perfect though, but it doesn't need to be perfect
for a tube to work OK.

Large transmitter tubes have vacuum pumps connected to evacuate them
and prevent the cathodes from bombardment by heavy positively charged
molecules and atoms
of gas.

The sound of gas is much harder to discern when the gas quantity is
extremely small, as it is in most tubes that operate wiothin thier
spcification,
but usually gas causes noise and and if enough gas is present the tube fails
to operate correctly.

But that's another story; but there us sometimes no shortage of hot gas
in the postings sent to r.a.t sometimes.

Patrick Turner.

On Tue, 10 Jan 2006 15:12:29 GMT, wrote:

Yes, I know it sounds like a stupid question. And maybe it should be
stated as "How do tubes get hot?"

But, think about it: tubes are full of vacuum. Vacuum is an excellent
insulator. What makes the glass hot?

There's your mistake, vacuum is not an insulator, exactly... it allows the
passage of electromagnetic waves, which manifests as heat when hitting something
and being absorbed, such as glass... go outside and look up - see the big bright
ball in the sky?

The only think I can think of is that the internal components must radiate
a lot of infrared light (which, by black body theory, means they must be
really hot), and the glass envelopes absorb it.

Black body theory? Like Lola Felana?

Does anyone here know what actually happens?

yes

/kenw
Ken Wallewein
K&M Systems Integration
Phone (403)274-7848
Fax (403)275-4535

www.kmsi.net