[Amps] Anodizing aluminum, painting etc.

[Will Matney]

Jim,

That's what I'm getting at really. The amount of solid aluminum in the heatsink will cause it to stay cooler longer, and the fins are used to dissapate the heat into the atmosphere (surface area). Since RF transistors are only producing power mostly while a signal is present, their duty cycle is lower than one which is powered up continuous. This allows the heat from the transistors to be dissapated between key downs, and the size of the heatsink is what counts here along with the design of the fins. Someone mentioned about Avid saying to use black where there's no other source of heat around. To me, this is pretty hard to do especially in a mobile situation. Since black abosrbs heat, I would think what heat is absorbed would be added to the heat that the heatsink has to dissapate into the atmosphere from the device. Black would be ok I guess in a dark room, but in the daylight, I can't see it unless it's hidden from infrared radiation. You can leave something with a dark color inside a car, and it will get hot on a sunny day. Matter of fact, it can get pretty darn hot! Since the heatsink is already this hot, when you turn on the amp, and the transistros produce their own heat, that heatsink would have to be hotter than it normally would be if IR radiation hadn't gotten to it. It would have to be an addative effect. If it was silver, it would have reflected this IR radiation, and to heatsink would have been much cooler for the starting operation of the transistors. That's just the way I see it, or is my personal opinion.

Best,

Will

*********** REPLY SEPARATOR  ***********

On 8/17/06 at 1:16 PM Jim Tonne wrote:

>> Making the heat sink heavier by making it a larger block 
>> doesn't necessarily make it a better heat sink.
>
>I look "mass" (weight) as a time-constant.  Bigger sink
>stays cool longer while it is soaking up heat.  But then too
>it retains that heat for a longer time than a light-weight sink.
>
>>  it is surface area that gets rid of the heat.
>
>- JimT
>
>
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