[Elecraft] KPA1500 Power Supply Fan Noise

John Langdon WOYB10051 at outlook.com
Tue Jun 11 05:29:56 EDT 2019


Eric,

My KPA1500 RF deck is mounted on a high shelf, and the power supply is on low shelf below the desk.  I have the fan speed on the RF deck set to 2 as a minimum.  I almost never notice the PS fans, when I hear noise it is the RF deck. During the ARRL DX CW the fans reached 4 and it was loud enough to need headphones, in most operation it is not.  The PS noise you are describing does not seem normal to me.  Can you make a video/audio recording and post it on the web somewhere?

73 John N5CQ


-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On Behalf Of Eric Norris
Sent: Tuesday, June 11, 2019 3:47 AM
To: Peter Hall <P.Hall at curtin.edu.au>
Cc: elecraft at mailman qth. net <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] KPA1500 Power Supply Fan Noise

Apparently I was not clear enough in my message.  It is the PSU fan noise that is deafening, not the RF deck.  Like Peter, my PSU sits on the floor underneath a wooden operating desk that holds the rest of the K-line.  The noise from the PSU is high-pitched and piercing.  The only thing I can liken it to is a four-rotor Mazda prototype IMSA GTP race car from the early 90s.  Brain-piercing, tear-your-hair-out, heard-from-every room-in-the-house louder than hell, and has been so since the day it darkened my doorway--with the RF deck at idle.

73 Eric WD6DBM

On Tue, Jun 11, 2019, 12:54 AM Peter Hall <P.Hall at curtin.edu.au> wrote:

> Hello Eric
>
> There's no doubt that a KPA1500 physical installation needs some 
> careful attention to the noise aspect.  That said, I'm a bit surprised 
> by your problem with the PSU fan.  I can certainly hear mine but, 
> overall, the noise is entirely dominated by the RF deck fans.  I've 
> located the PSU under my operating desk, which is made of a dense particleboard material.
> The RF deck sits alongside my TS-890S transceiver on the desk.   I can hear
> the PSU fan if I put my head below desk level but, even then, I don't 
> find the fan to be particularly high-pitched in its acoustic output.  
> Could you possibly have a faulty fan (maybe excess nearing noise)?
>
> On the other hand, I do find the RF deck fans test my patience a bit, 
> especially since the last round of major firmware updates which start 
> the cooling at a lower heatsink temperature.  That probably works well 
> in a high-output environment, where it no doubt delays the onset of 
> heat soaking.  But when the amplifier "loafs" in a low power, low duty 
> cycle environment as it does in some of my applications. it just 
> starts the noise prematurely.  It'd be great to see something like an 
> "80m rag-chew" option for those times!
>
> 73, Peter (VK6HP).
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> <elecraft-bounces at mailman.qth.net>
> On Behalf Of eric norris via Elecraft
> Sent: Tuesday, 11 June 2019 7:57 AM
> To: lists at w2irt.net; lists at w2irt.net; Elecraft Reflector < 
> elecraft at mailman.qth.net>
> Subject: [Elecraft] KPA1500 Power Supply Fan Noise
>
> More broadly, has there been any progress on reducing the piercing 
> power supply fan noise on the KPA1500 when only using it as a tuner or 
> an antenna switch?  I complained about this a year ago, and I find it 
> completely unacceptable.  No set of noise-reducing headphones that I 
> have tried works well enough to make the noise tolerable.  I've tried 
> moving the PS deck around with minimal improvement.  This just doesn't 
> seem to fit Elecraft's philosophy of a quiet operating environment.  
> Why do these fans have to operate at full throttle when there is 
> minimal current draw from the rf deck?  Why do these fans create such 
> a piercing high-pitched note? If there is no response from Elecraft, 
> what have other ops done--short of moving the PS into an adjoining room--to mitigate the scream?
> Thanks,
> 73 Eric WD6DBM
>
> Sent from Yahoo Mail on Android
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