[Amps] Fan Noise in GS-35b Amplifiers

N1BUG paul at n1bug.com
Thu Feb 20 09:26:55 EST 2014

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!

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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