[Amps] Muffin Fans and hot exhaust

[Pete Smith]

At 08:38 AM 7/22/02 -0400, Ron wrote:
>In working with fans , pressures developed are less than 1 inch of water
>where 1 atmosphere is roughly 32 feet of water or about 14 lbs / sq. in.
>If it develops more than say 1/2 in of water , it is a blower.
>All my experiments show that it works better blowing than sucking for
>the reasons mentioned by Dave.  If there is no choice ,as in a high
>efficiency furnace with a blower placed on the exaust plenum,  you got
>to do what you got to do.

I'm sure this is all true, but in certain situations, a muffin fan in 
suction mode can be a great help.  I got a couple of 3" diameter 115 volt 
muffins, wired them in series, put one behind my transceiver to help 
exhaust air from the final heat sink, and the other atop the power supply 
section of my SB-220 to augment the main muffin fan which blows in across 
the tube envelopes.  In both instances, temperatures went down noticeably, 
and because of the reduced voltage the fans are inaudible.

73, Pete N4ZR

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