[Elecraft] KPA-1500 Fan Noise - YouTube ?

[Don Wilhelm]

Only one bit of correction.  If the output power is 1500 watts and the 
efficiency is 50%, that 1500 watts is only half the total power 
consumed, so there is 1500 watts of power that must be exhausted as heat.

Yes, it is all thermodynamics, that heat must be dissipated somehow. 
Fans are the obvious solution.

73,
Don W3FPR

On 6/1/2018 8:59 PM, Dr. William J. Schmidt wrote:
> So just a bit of thermodynamics... if the input to any amplifier is 1500 watts and it is 50% efficient, since energy is conserved, 750 watts will come out in another form.. and in this case it's heat.  Doesn't matter what the converter is (transistor, tube, resistor, etc.).  It all behaves the same.  Need to get rid of 750 watts of heat.  The only difference may be the way the heat is taken away of the converter... convection (heat sink), forced convection (heat skin plus fan), liquid convection (water cooled heat sink).  The poison is the heat removal device not the converter.
> 
> 
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> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Bill Stravinsky via Elecraft
> Sent: Friday, June 1, 2018 7:33 PM
> To: Elecraft Reflector <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] KPA-1500 Fan Noise - YouTube ?
> 
>   Rich
> 
> You pretty much hit the nail on the head about solid state amps.  As they say there's no free lunch.  Solid state has made great strides in high power ampsbut its still solid state and a p/n junction or some form thereof.  1500 watts of heat in those junctions has to be cooled down or it won't be long before it needsnew parts.
> Depending on your operating habits (contesting, casual, or whatever) there will be varying degrees of fan noise.  The higher the duty cycle the higher thefan requirements.  Pick your poison, a small light weight amp easy to move around or one you need a fork lift to pick up.  I prefer tube amps for a few reasonsand have the Acom 2000a (and an Alpha 89 that now sits in the living room temporarily) but I'm still glad I got the kpa1500 at least so far.
> The kpa sits nicely on top of the Acom without causing the table they sit on to crash to the floor in pieces, hi.  I'm surprised nobody has made a you tube ofthe amp in operation actually.  But there are only just over 200 of the new amps out there.  Good luck with your investigation, Rich.
> BillK3WJV
> 
>      On Friday, June 1, 2018, 8:00:29 PM EDT, Richard Thorne <rthorne at rthorne.net> wrote:
>   
>   This fan noise issue has me concerned to the point that I’m considering cancelling my order.
> 
> While the amp won’t be on my operating desk, it will be on a rack next to my operating desk.  Remoting the amp is not an option. Quite frankly I have no interest in remoting the amp.
> 
> Is there anyone out there that has a KPA-1500 willing to post a YouTube video so we can hear the fan in action and judge the noise for ourselves?
> 
>  From the research I’ve done it appears that if you want a solid state amp, regardless of make, you need to be prepared for fan noise.
> 
> Thanks
> 
> Rich - N5ZC
> 
> Sent from my iPhone
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