Bill Turner wrote:
> I notice that some posters are using the term "conduction cooled"
> lately and I'm curious what they mean by it. Aren't all amplifiers
> "conduction cooled" one way or another? Heat is conducted away by
> some means, whether directly by air or liquid or indirectly to a heat
> sink which is in turn cooled by air or liquid.
>
> I'm aware of "radiation cooling" too, but I doubt many high power
> amplifiers use that.
>
> Some clarification would be appreciated.
There are 3 ways for something to cool - conduction, convection and
radiation. See for example
http://www.mansfieldct.org/schools/mms/staff/hand/convcondrad.htm
Radiation (electromagnetic) is unique in that it occurs in a vacuum too,
whereas both convection (flowing fluid) and conduction (solid contact)
both need two items in contact.
Conduction tubes are cooled by mounting to a heatsink. See for example a
Y799 amp, with a conduction cooled variant of the 4CX250B. Note the
berrilium oxide link to *conduct* heat.
http://www.g8wrb.org/y799.shtml
Note, in *any* practical system there will be a combination of
conduction, convection and radiation cooling. That Y799 will emit IR
radiation, so cool by radiation. It is also in contact with air, so will
pass heat to the air by convection. It is just that conduction will
dominate.
--
David Kirkby,
G8WRB
Please check out http://www.g8wrb.org/
of if you live in Essex http://www.southminster-branch-line.org.uk/
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|