[Drake] Cooling fans - blow in or out?

[Steve Thompson]

On Monday 14 February 2005 17:19, Anthony W. DePrato wrote:
> >If you want to actively cool a component surface, you need to blow onto
> > it. Air naturally follows a path of least resistance. Air sucked into a
> > fan tends to have a neat, ordered flow and will skirt round components,
> > leaving a thin layer of stagnant air right on the surface. Air coming out
> > of the fan blades has a lot of turbulence, and it's this that breaks up
> > the stratified flow and gets moving air in contact with the component
> > surface.
> >
> >Steve
>
> Yes but does this not also make hot spots on the back side of the tubes..
> seems like a study was done years ago about cooling transmit tubes with
> side mounted fans.. and tests showed that a hot spot showed up on the back
> side of the tube away from the fan.
> air sockets came about for this reason. I alway put the fan on top of all
> six of my c-line transmitters during contest.
> correct me if i am wrong about this study.
I've heard and read the same, and doing the experiment myself is on the list 
of things to do one day. 

Lest anyone misunderstand my message quoted above, I didn't mean to imply that 
blowing was necessary to cool a typical Drake PA compartment - my intention 
was to highlight the situation where blowing rather than sucking is needed.

Cheers,

Steve