[Premium-Rx] Fan Noise

[W2HX]

In the 110A, the fan noise is predominantly from the fact that it runs at
400Hz. The 110A is very, very difficult to replace the fan. Dozens have
tried (check the archives of this list and the harris-radio list).  I too am
among those who are trying! Many have tried centrifugal fans, but they don't
always push the air just in the right place to hit the safety interlock air
vane. If they don't hit the vane, the system won't start up.  I've been
working on the problem on and off for a few years. Did some intake/output
temperature studies at one point in time, but that was probably a few years
ago.

73 Eugene W2HX
-----Original Message-----
From: premium-rx-bounces at mailman.qth.net
[mailto:premium-rx-bounces at mailman.qth.net] On Behalf Of Tisha Hayes
Sent: Friday, February 11, 2011 12:25 PM
To: premium-rx at mailman.qth.net
Subject: [Premium-Rx] Fan Noise

You can try to run the fan when it is removed from the transmitter. Some
designs are just "screamers", usually this is due to the blade design but I
have run across some with very noisy bearings. A good example of a loud fan
is what is installed in the Harris RF-350K power supply deck. Many of those
suffer from bearing problems.

If you can find the right fan frame size you may run across a fan that will
give you the same CFM and pressure rating as what you are using now. When in
doubt, go higher.