[Milsurplus] GRC109/R-1004A arrived!

[bcarling@cfl.rr.com]

Interesting thank you. That just dispelled a hole in my engineering knowledge due to lack of design experience over the years.

Sent from myTouch 4G

----- Reply message -----
From: "J. Forster" <jfor at quikus.com>
To: "gvbbcarling at cfl.rr.com" <bcarling at cfl.rr.com>
Cc: <milsurplus at mailman.qth.net>
Subject: [Milsurplus] GRC109/R-1004A arrived!
Date: Wed, Sep 14, 2011 10:39 am


Tradition.

Radiative transfer is proportional to (sigma) T^4

Sigma is the Stefan-Boltzman constant.
That is the Fourth power of absolute tempertature. Do the numbers.

-John

================

> Every piece of solid state power equipment I have ever used with a heat
> sink has it colored black. With a few exceptions for on painted aluminum
> surfaces, that is about it. Engineers have used this technique for about
> 40 years or more. No they usually do not run hot enough to melt solder.
>  I am fairly sure that the engineers who painted the grc109 boxes black
> did so for a reason.
>
> Sent from myTouch 4G
>
> ----- Reply message -----
> From: "J. Forster" <jfor at quikus.com>
> To: <bcarling at cfl.rr.com>
> Cc: <milsurplus at mailman.qth.net>
> Subject: [Milsurplus] GRC109/R-1004A arrived!
> Date: Wed, Sep 14, 2011 9:41 am
>
>
> Painting the heatsink black is essentially pointless. Unless the heatsink
> operates at high temperature...  think melting solder at least...
> radiative transfer is insignificant.
>
> -John
>
> ===============
>
>> Interesting thoughts Richard...
>>
>> I have never heard any amateur say that his GRC109 failed due to
>> overheating...
>>
>> Also note that the case is a giant heatsink and painted black which is
>> the
>> best color for
>> re-radiation of heat to the outside. Now maybe if you used it for 8
>> straight hours at field
>> day here in FLORIDA, you could overheat it! Now there is an idea for an
>> experiment and
>> a magazine article.,.... NAH!
>>
>> On 13 Sep 2011 at 20:18, Richard Brunner wrote:
>>
>>> Another thing: Military communications must be infrequent and
>>> brief,
>>> because most mil equipment is boxed up tightly with little concern
>>> about
>>> heating, and the GRC-109 is no exception.  The transmitter would
>>> have to
>>> be taken out of the box to survive amateur operation.
>>>
>>> Richard, AA1P
>>
>>
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>
>