[TMC] Rotron blower

[Robert Downs]

Bob,

These comments aren't specific to Rotron blowers but would apply equally to dynamotors and inverters.  You didn't say what type of bearings it has but I would guess most likely small precision ball bearings.  If the blower makes the same undesirable noise with new bearings as with the originals, I would guess that the armature has significant end float, and that the fix would be to either add (probably) or subtract (less likely) shims.  Ideally, you should set up a dial indicator measuring axial movement of the armature relative to the frame or housing.  With ball bearings, this should be zero.  At a guess, you need to add shims.

Robert Downs


-----Original Message-----
From: tmc-bounces at mailman.qth.net [mailto:tmc-bounces at mailman.qth.net] On Behalf Of Robert Nickels
Sent: Friday, September 27, 2019 23:58
To: tmc at mailman.qth.net
Subject: [TMC] Rotron blower

I'm looking for tips on noisy Rotron blowers, the one in question being 
used in a PAL-350 amplifier.�� I was told that bearing replacement is 
often needed so I got some new bearings and replaced them, but the 
rattly metallic noise continues unabated. The position of the armature 
between the end bells seems to be determined by shim washers in each 
end, and I kept the same number in the same place as originally, but is 
this something that is tweaked for each motor?��� I'm sure I didn't get 
the bearings in precisely the same position on the shaft but assume they 
move as needed when the end bells are attached and tightened.�� The 
motor starts and runs fine and produces plenty of air, it's just this 
mechanical noise in addition to the expected white noise of normal airflow.

73, Bob W9RAN

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