On Sun, 2006-06-18 at 21:07 -0500, Duane A Calvin wrote:
> Jerry,
> Carl's answer is the short and sweet one. I had an interesting
> exchange of letters with the TT president about the Centaur when it came
> out and I documented the noise level in my shack caused by it. No help.
> However, I did take it in to the acoustic lab where I work and had one of
> their engineers look it over. I had noticed that with the covers off,
> the fan was relatively quiet, but if you put anything close to the fan
> intake, it got very noisy very quickly. The engineer agreed and said it
> was the shock wave (if I'm remembering it correctly) from the leading
> edge of each fan blade which was striking the slot openings in the
> cabinet side (which is, essentially, too close to the fan). Sort of like
> playing cards on a spoked bicycle wheel. The best answer is to do what
> Carl did and remove the material in front of the fan, or, as one fellow
> did, use a pair of pliers and "twist" each of the bars so that it takes
> on a 45 degree (or so) angle. The latter option will reduce, but not
> eliminate the noise. I took the more expensive route, and traded my
> Centaur on a Centurion. No more noise - hi!
>
> 73, Duane
Its hard to quiet a siren (where the fan blades chop off the air flow
through holes), but maybe if the grill was removed and a few feet of 4"
flexible sound silencer duct was attached, it would be passably quiet.
Like used for high velocity air conditioning ducts. Or a box inlet along
side made of fiberglass lined rigid ducting material.
--
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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