> That makes some kind of sense, but it has made me rather suspicious of
> blowing air onto one side of the tube without also making sure some air
> gets around the other side too.
Right on, Ian.
This is the same principal that makes an airplane fly.
The velocity of air passing around the tube envelope
must be sufficient to create a low pressure area. This
will allow the air stream to conform to the shape of
the tube envelope all the way around it. One can demonstrate
this principal by directing a hair dryer to the front of your
neck. If the blower is powerful enough, you can feel the
air all around your neck, and the hair on the back of your
neck will dry without direct application.
That is why I do not understand all the "dumbing down"
of amplifier cooling systems going on in the interest of
ham shack noise reduction. IMO, very few amplifiers designed
for the amateur market have excess air to spare. Few hams
have stood around an industrial 1500 watt RF generator and
heard the noise required for 100% duty cycle operation.
There is no free lunch here....our cooling systems should
be kept in a clean, well-lubricated state; not shackled with
rpm reduction devices in the line. Each blade in a blower
or fan is a miniature airfoil. Efficiency is greatly reduced by
dirt/dust adhering to them.
You fortunate guys that have a closet full of spare tubes
may disregard the above advice!
(((73)))
Phil, K5PC
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