Or, of course, anyone who really doesn't care about noise but wants to move
a lot of air in the equivalent space could use a Nidec TA500 wide body
B34607-16, like I do....190 cfm, about double the air volume for the same
back pressure as all the Pabst 120mm models...sounds a bit like a 747 on
full takeoff thrust, though. -WB2WIK/6
"Success is the ability to go from failure to failure with no loss of
enthusiasm." -Winston Churchill
> -----Original Message-----
> From: W0UN -- John Brosnahan [SMTP:shr@swtexas.net]
> Sent: Wednesday, February 18, 2004 5:09 AM
> To: amps@contesting.com
> Subject: [BULK] - Re: [Amps] tube cooling
>
> My experience had been that there were only TWO kinds
> of muffin fans that can be added to the back of an Alpha
> amp.
>
> 1) Quiet ones that make no difference in the actual
> temperature of the exhaust air.
>
> 2) Noisy ones that push a lot of air and can drop the
> exhaust air by as much as 10 deg F or more.
>
> On my own 87As I had some muffin fans that I added
> that were very effective but noisy. During my tenure
> at Alpha/Power I decided to see if there was a muffin
> fan out there that moved enough air to lower the
> exhaust temp significantly and was still relatively quiet.
> Finding a muffin fan that can work into a back pressure
> and still be quiet is not an easy task.
>
> I found ONE model of muffin fan that I was happy with and
> that is what Alpha began supplying. If you are not using
> this muffin fan then your amp is probably either noisy
> or not really being helped all that much by an auxiliary fan.
> I found that the exhaust air was reduced by about 8 deg F
> by these two models.
>
> The 115v quiet model is a Papst 4530Z,
> and the 230v quiet model is a Papst 4580Z.
>
> And if you really need a lot of extra air movement then
> the 230v higher flow (noisy) Papst 4650Z and the
> 115v higher flow (noisy) Papst 4600Z is the answer.
> They are quite a bit more noisy but are probably the
> best if a lot of extra air is needed.
>
> The exhaust temps were measured with a thermometer
> in the air stream on top of the amp during normal contest
> operation. Typical values on the Alpha were in the 140+ deg F
> range.
>
> 73--John W0UN
> << File: ATT170726.txt >> << File: ATT170727.txt >>
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