Will Matney wrote:
> Bill,
>
> One thing about conduction cooled tubes to me is that there is a hot spot at
> 180 degrees from where it mounts to the heatsink. A convection cooled tube
> with heat fins has cool air passing over these fins 360 degrees around the
> circumferance. I'm not sure if any tests have been done, but this may lead to
> the conduction tube failing before the convection one, I don't know.
>
> Best,
>
> Will
I had a few email exchanges with Reid at Eimac about CC tubes.
Apparently they do run a lot warmer (typically) and so their life is
shorter than air-cooled tubes. The manufacturing cost is higher - much
of that due to the waste disposal problem of the BeO that is used is
carcegogenic. So all this adds to their cost and relative unpopularity.
Here is a data sheet on pretty big CC tube with an anode dissipation of
1 kW. I'm not aware of any bigger ones.
http://www.g8wrb.org/data/Eimac/Y-477.pdf
It's a special version of the 4CX1500B.
There are other conduction cooled tube data sheets at
http://www.g8wrb.org/tetrodes.shtml (tetrodes)
and
http://www.g8wrb.org/triodes.shtml (triodes).
>
> *********** REPLY SEPARATOR ***********
>
> On 11/3/05 at 1:26 PM Bill Fuqua wrote:
>
>
>>If a tube is convection, conduction, radiation, liquid or vapor phase
>>cooled has to do with how heat ,produced by the kinetic energy from
>>colliding electrons, is removed from the anode. From there it may pass
>
>>from one place to another until ultimately dissipated into the environment
>
>>by all sort of heat transfer mechanisms. There are some very minor points
>>about this that can be argued, such as, in the case of the convection
>>cooled tubes or even the radiation cooled tubes where there is thermal
>>conduction from the side of the anode where the electrons collide to the
>>surface where it is dissipated. But that is a very minor point except to
>>the nitpicking purest.
>>
>>73
>>Bill wa4lav
>>
>>
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>
>
>
>
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--
David Kirkby,
G8WRB
Please check out http://www.g8wrb.org/
of if you live in Essex http://www.southminster-branch-line.org.uk/
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