[Amps] Fan sounds like F-15

[KA4INM]

On 11/21/13 11:32, Vic K2VCO wrote:

>     I've been using my new 4CX1000A amplifier for a few days. It works great.
>     But  there is one problem that I need to solve: the fan -- it's a flat
>     centrifugal type -- here's a construction photo from my website:
>     [1]<http://www.qsl.net/k2vco/4CX1000A/Underside.jpg>
>     which provides somewhat more air than is needed. But it also provides more
>     noise  than  is  needed,  somewhat  like  an F-15 pilot kicking on his
>     afterburner. OK, a little exaggeration. But not much.
>     I would like to implement a thermostatic control system. I envision a sensor
>     stuck in the chimney above the tube that would operate a relay to switch the
>     fan from low to high speed.
>     Has  anyone  done  this?  What  kind of sensor should I look for? What
>     temperature should it switch at? The fan is an AC motor with a capacitor
>     across half of the field -- is it safe to reduce speed by putting a resistor
>     in series with the motor?
>     I know a simple solution would be to remote the fan, but it would mean
>     building a new amplifier! And good noise-cancelling phones cost $300.

   Block off half or three quarters of the blowers air intake to unload 
the motor.
-- 
   Ron  KA4INM - Youvan's corollary:
                 Every action results in unwanted side effects.