On Mon, 2007-12-24 at 12:22 -1000, Ken Brown wrote:
> My Titan 425 sits on some packaging foam sheets. The foam is between the
> front supporting bail and the desk top, and also between the rear fee
> and the desk top. That makes a huge reduction in the vibration
> transferred into the desk, and overall less noise in the shack. Someday
> I'll replace the grommets that are supposed to isolate the vibration
> from the chassis. If those grommets are as hard as the ones I removed
> from the vacuum relay mounting, new ones will make an improvement. I
> wonder if there is a way to get the squirrel cage precision balanced? It
> seems like the noise is mostly from vibration due to imbalance, and the
> air flow noise is not the problem.
> DE N6KB
> > Are there any proven approaches to quieting down the fan noise on the
> > TT 425 Titan amp? Slow speed is tolerable (but not great), but High speed
> > just causes lots of "rattling" noise.
Balancing a squirrel cage is possible. Even without fancy tool but it
will take much patience. Its easiest if the motor has no cogging, e.g.
no magnetic stopping points. Then you can start with the shaft
horizontal and see which side of the cage always stops down. Then you
add weight opposite the heavy spot (modeling clay is handy for the
initial experiments) until the cage will not stop the same place twice
after a bunch of slow speed spins. Then you replace the weight of the
clay with solder or glue. When that's set you can see if the static
balancing was good enough or if you need to move that weight in or out
on the blade to achieve dynamic balance. Alternatively once you find the
balance with clay, you can remove material from the opposite side to
match the weight of the clay. With practice it takes me about half an
hour to do a static balance on my trailer wheels in place. I can't
balance them on a machine because the bolts are out at the edge of the
drums and the drums are badly out of balance too.
73, Jerry, K0CQ
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