[Amps] Fan Noise in GS-35b Amplifiers

Jack C. Shutt w9gt at frontier.com
Thu Feb 20 09:51:18 EST 2014


Yes, that Dayton blower is a good one to use, however, it is still quite loud even with the slower speed.  Of course, you can reduce the fan speed on receive, but when transmitting, the noise is objectionable.  I'm wondering if slower speed and higher volume really translates to adequate cooling if the actual air pressure is not there.  Many blowers will provide what seems to be adequate air flow, but with back pressure, just don't provide sufficient flow.  I have seen several European hams' GS-35b amps with what look like just "muffin" type fans.  Those things are pretty loud anyway and I don't think they move enough air.  I have seen examples, also where they are using two "muffin" type fans.....one above the anode cooler pulling air out of the enclosure and one below the chassis blowing upward thru the tube.  There has to be some of you folks out there who have a "quieter" solution??
73,  Jack, W9GT
 

________________________________
 From: N1BUG <paul at n1bug.com>
To: Jack C. Shutt <w9gt at frontier.com>; "amps at contesting.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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