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.
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
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Staunton, Illinois
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email: b...@wjschmidt.com
-----Original Message-----
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bill Stravinsky via
Elecraft
Sent: Friday, June 1, 2018 7:33 PM
To: Elecraft Reflector <elecraft@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
<rtho...@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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