[Amps] Fan Noise in GS-35b Amplifiers

[Carl]

Dont overlook a good muffin fan either. The EBM Papst 4600N was used in 
later production LK-800's using the 3 3CPX800A7's at about 3100V. That is a 
lot of fin area and back pressure.

They are also fine to run at reduced voltage in receive or low duty cycle.

Carl
KM1H


----- Original Message ----- 
From: "N1BUG" <paul at n1bug.com>
To: "Jack C. Shutt" <w9gt at frontier.com>; <amps at contesting.com>
Sent: Thursday, February 20, 2014 9:26 AM
Subject: Re: [Amps] Fan Noise in GS-35b Amplifiers


>I don't know what the "recommended" blower is, but bear in mind slow speed 
>blowers can be much less noisy than high speed ones. They tend to be 
>physically larger, however. On some prior amps I used high speed (2500-3000 
>RPM I think) blowers that were physically rather small. They got the job 
>done but were very noisy. On my current generation 4CX1500B amps I use 
>Dayton 2C647 blowers. They run at 1500 RPM, but move about the same amount 
>of air by using a larger squirrel cage. They are much quieter. I suspect 
>even this amount of noise would be objectionable to many people but those 
>blowers are far less noisy than the 4" fan in my rack mount server case 
>that houses the shack PC. Something has to be done about that fan!
>
> 73,
> Paul N1BUG
>
>
> On 02/19/2014 11:07 AM, Jack C. Shutt wrote:
>> I have gathered from all the info that I have read on amps using
>> the GS-35b that a healthy air flow is necessary to keep these
>> tubes happy.  Unfortunately, the 100 CFM squirrel cage blower
>> that is recommended for this purpose is quite noisy.  Any
>> suggestions for an effective cooling arrangement that is quieter?
>> I thought about remotely locating the blower and using a hose
>> duct to the amp, but this is just not practical in my shack.
>> Suggestions?   73,  Jack, W9GT
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