James, I had to replace two of the switches when they broke.
I have have 572B's. A little $10 fan from the drugstore works good.
Best regards, Jim FitzSimons W7ANF
----- Original Message -----
From: "James Parsons" <k5rov@wcc.net>
To: <tentec@contesting.com>
Sent: Saturday, September 09, 2000 11:09 AM
Subject: [TenTec] Modifying the Centaur
>
> Hi, Gang...
>
> I have a Centaur amplifier that I bought new from TT some years ago. It
> has been a faithful performer (except for those cheap switches), but it
> sure does suffer from high fan noise. It seems that 100 CFM is a lot of
> air to move across those tubes. I built a lot of amplifiers during my 58
> years of hamming, and a number of them were 811 type, but I never blew
> that much air across them.
>
> I wonder if anyone has replaced the fan with a slower one, or maybe put
> a series resistor in the line with the existing fan? I need to do
> something because the constant blower noise over a period of operating
> hours is sure tiring. It seems my options are:
>
> 1. Replace the fan with a slower one (will the tubes get too warm?)
> 2. Slow the fan down.(how many CFM?)
> 3. Disconnect the fan and use some muffin fans on the top of the
> cabinet, blowing towards the tubes.
> 4. Replace the 811 tubes with 572B tubes and much less cooling.
>
> I have found that changing the mounting of the fan, as some have
> suggested, has not worked.
>
> Has anybody done anything about this? I have never figured out why TT
> found a need for 100 CFM for 811 tubes unless it is the way the fan had
> to be mounted and the fact that the tubes are in a line of three in a
> horizontal plane with the fan.
>
> I would like to hear from anyone who has ACTUALLY made a modification to
> this amplifier for this purpose.
>
> Thanks and 73 de Jim, K5ROV
> --
> James (Jim) Parsons, K5ROV USAF, Ret. Ham for 58 yrs.
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