[Milsurplus] GRC109/R-1004A arrived!

[Bruce MacMillan]

According to the AAVID/Thermalloy website:

"Heat sinks cooled by natural convection may benefit from an anodized 
finish, but the added cost of the finish may not be justified when the 
part is used in forced convection cooling.
Surface emissivity limits the amount of heat transfer due to radiational 
cooling. With 1.0 being perfect (black body) emissivity anodized 
aluminum is 0.85 and unfinished is 0.05."

This could explain why early mobiles like the Motorola T-power had black 
heatsinks and relied solely on convection whereas computers & test 
equipment with fans use plain.

Perhaps the designer of the RS1/GRC109 thought that because the unit was 
sealed that there was enough heat generated by the vacuum tubes to 
warrant better thermal dissipation.
Then again black is harder to spot. The later replacement RS6 is black 
as well but well ventilated. A lot of the WW2 spy sets were available in 
black only (standard spy colour).

Bruce   ve7mt



On 9/14/2011 5:15 PM, John Hutchins wrote:
> All -
> Black heat sinks seem to dissipate, distribute, suck off, more heat from
> the device; when looking at the heat sink specifications.
> I believe units painted  the Black in WW2/Korea/Viet Nam was:
>    1. cheap paint.
>    2. for light, reflection, glint, abatement
> Now I could be wrong.... being anything with a tube ran hot anyway.
> Hutch
>