[Elecraft] KPA-500 fan noise

[Don Wilhelm]

Do you have the full design parameters for the KPA500 cooling, air flow 
required at specific temperatures to protect the MOSFETs, current and 
voltage capable of being delivered by the KPA500 circuits to the fan at 
each of 3 fan speeds?  I certainly do not have those parameters.  That 
information would be required to make any intelligent swap of the fan.

I would not know what parameters would qualify a fan to be of higher 
quality than what is in there already-  Greater air flow usually means 
more noise, and could mean more current draw.
A lower fan speed would be less noisy, but would likely reduce the air 
flow and cause greater heating of the MOSFETs.

I do not think changing the fan would be a task to be taken lightly, 
there are too many factors at play.

Sending the KPA500 back to Elecraft because the 'new improved' fan 
needed more current than the KPA500 could supply, or sending it back to 
change the PA sandwich after installing a slower fan (or one with a 
lower blade pitch) that was more quiet, but failed to move enough air 
could become an expensive task.

73,
Don W3FPR

On 6/3/2014 10:19 AM, Harry Yingst via Elecraft wrote:
> I would tend to believe that replacing the cheap fans with
> higher quality fans would be a improvement in design.
>
> If the K3 cannot handle what little extra current draw the fans have
> then I would certainly question the well engineered aspect of it.
>
> As in any product cost is a factor and I'm sure Elecraft
> has to weigh the cost associated with various parts.
>
> For many the noise will not bother them for others it will so for the ones
> who  do find the additional noise bothersome they can simply swap out
> the fans for a higher quality fan and enjoy the reduction in fan noise.
>
> To my ears (and I'm partially deaf from when I was in the Navy) the stock
> fans in the K3 had a grating sound that added to the background noise.
> Replacing the fans was a worthwhile improvement and made copy easier.
>
> I'm not afraid of improving a design where there is room for improvement.
>
>
>
>
>
>
>
>
> ________________________________
>   From: Jim Brown <jim at audiosystemsgroup.com>
> To: elecraft at mailman.qth.net
> Sent: Monday, June 2, 2014 11:16 AM
> Subject: Re: [Elecraft] KPA-500 fan noise
>   
>
> On 6/2/2014 7:56 AM, AG0N-3055 wrote:
>>> You could always try replacing the fan with a quieter fan.
>> I would consider that myself, but only with one recommended by the good people at Elecraft.
> It is generally a bad idea to try to re-engineer a product, especially
> one that is well designed. In this case, I would consider it a really
> bad idea.
>
> 73, Jim K9YC
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