Hi Jim,
I had this same problem with my Centaur, and communicated with TT
about it. I did not want to reduce the fan volume, although I'll bet you
could at least cut it in half and still get adequate cooling. If you do
that, you might want to open the case and swap the first and 3rd tube
every 6 months or so to keep them aging at a similar rate. Also realize
you need to provide cooling for the power supply as well, and it's behind
all the 811A's!
I had one of our thermal/acoustic engineers at work look at the
design because you'll find if you operate it with no cabinet that it's
quiet. The problem is the fan input is too close to the side of the
cabinet. (fan blade leading edge shock wave hitting the obstructions &
slots generates the noise) This engineer recommended a two-step solution
to me:
- First, try removing steel from the cabinet using a large
chassis punch. Round edges will be much quieter than the straight slots.
- If that doesn't help, then cut a round hole the size of the
fan input in the side of the case. You will need to cover the hole with
some sort of screening to reduce RF escaping the amp, but this should
completely eliminate the noise (depending on the screening you use).
I never tried the suggestion. Instead I traded my amp on a Centurion
which was VERY quiet!
73, Duane AC5AA
On Thu, 13 Sep 2001 09:14:40 -0500 "James Parsons" <res075cz@gte.net>
writes:
> I have a Centaur I bought new from TenTec some years ago. Because
> of
> interference to neighbors I have used it very little until now. I am
> now
> able to use it freely and I am enjoying it. My operation is solely
> CW.
>
> My problem is that durned fan! It drives me nuts and I can hear it
> even when
> using my headsets. Surely someone else has had this problem and has
> done
> something about it.
>
> I would like to hear of your modifications. I thought of a fan with
> less CFM
> mounted in the place of the original fan. But I wonder if that last
> tube in
> the row would get sufficient cooling? These tubes are no longer easy
> to
> procure, and I don't want to shorten their life too much. .
>
> I cannot use an external fan mounted on top because of my equipment
> arrangement.
>
> Thanks to all....
>
> 73 de Jim, K5ROV...
>
> James (Jim) Parsons, K5ROV, CMSgt, USAF, Ret., San Angelo, TX
> Ham for over 60 yrs. 90% CW
> k5rov@arrl.net, QCWA, ARCI, Fists, ARRL, ARMS.
> EX: W1RLA, K5FBB, K4FEO, SV0WN (CRETE), SV0WN (RHODES),
> DL4NC, DL4JP, KA2FC (JAPAN), KA2JP (JAPAN).
> JOHN 3:16
>
>
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>
Duane Calvin, AC5AA
Austin, Texas
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