[Elecraft] KPA-500 fan noise

[Harry Yingst via Elecraft]

As I stated I do Not have a KPA500 It is in the future plans but I need to get some antenna work done first.

As I stated I replaced the Fans in my K3

I went with the Noctua brand because they are known for making a quality fan that is very quiet.


New Fan: Noctua NF-A6x25 FLX
Airflow: 17 cfm (29.2 m3h converted to cfm)

Noise: 19.3db
Speed: 3000 RPM (at 12 v)

Static Pressure: 2.18 mm
Current: 120 mA  (.12 A)

Original Fan: UTEC AT6015L-12L2B-ND2

Airflow: 15.4 cmf at 24.8db

Noise 24.8
Speed 3000 RPM (at 12v)

Static Pressure: 2.21mm
Current 100 mA

Yes I hear the air rushing but not the bearings




________________________________
 From: Jim Brown <jim at audiosystemsgroup.com>
To: elecraft at mailman.qth.net 
Sent: Tuesday, June 3, 2014 2:21 PM
Subject: Re: [Elecraft] KPA-500 fan noise
 

On 6/3/2014 7:19 AM, Harry Yingst via Elecraft wrote:
> Replacing the fans was a worthwhile improvement and made copy easier.

Something does not compute. The fan in my KPA500 is pretty quiet on RX, 
and only gets loud during long transmissions, continuing for a short 
time (a few seconds) after that. How does a fan that is noisy only on TX 
make copy difficult on RX?

Another thing that doesn't compute is that a lot of the noise I'm 
hearing is air flow. Perhaps the replacement fan is running slower, 
which would reduce air flow, which would reduce cooling. Again, I would 
approach all of this with great caution. Cooling of power devices is as 
important an element of the design of amplifier as any of the rest of 
the circuitry.

I think it's a mistake to think that we hear the fan because it's a 
"cheap" or inferior one. We hear it because it's working.


73, Jim K9YC

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