[Elecraft] KPA1500 Power Supply Fan Noise

[eric norris via Elecraft]

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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[Elecraft] KPA1500 Power Supply Fan Noise

[STEPHEN R ZUMBRUN]

Hello, all and Happy Field Day. Say I just wanted to comment about Elecraft 
service and the help they provided me to make a mod to my KPA1500. My KPA1500 
power supply fan was rather noisy. I had seen discussion on the reflector about 
this so I contacted Doug at Elecraft service. He ask if I could solder.  I 
informed him I could and he sent me a new 22 ohm, 3 watt resistor and i swapped 
it out with the 10 ohm, 3 watt resistor on the LED board of the power supply. I 
am much pleased with the sound of the power supply fan now after the 
modification. My amp is an early serial number and the new amps come with the 
22 ohm resistor on the LED board. So...if your power supply is a bit noisy you 
might consider this mod and contact Doug at Elecraft Service. The Elecraft part 
number of the resistor is E500128. 73, Steve W0SZ.
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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[turnbull]

Eric, I do not understand your problem with the PS and audible noise.    The 
larger fans in my KPA1500 are quiet.   Any noise is at low freq.    The RF deck 
does produce noise and I wish it did not.    My Sony noise cancelling phones 
handle this noise well.   Maybe your PS has faulty fans.   Are the bearings 
okay?    Please do not get annoyed with me but this is my experience.I suppose 
cooling junction temperatures low takes a lot of air.    My Acom 2000A tube amp 
is much quieter.73 Doug EI2CNSent from my Samsung Galaxy smartphone.
 Original message From: eric norris via Elecraft 
 Date: 11/06/2019  00:57  (GMT+00:00) To: 
li...@w2irt.net, li...@w2irt.net, Elecraft Reflector  
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 WD6DBMSent from Yahoo Mail on 
Android__Elecraft 
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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[Jim Brown]

On 6/11/2019 12:20 AM, turnbull wrote:

Eric, I do not understand your problem with the PS and audible noise.    The 
larger fans in my KPA1500 are quiet.   Any noise is at low freq.


Do you work keydown modes at high duty cycles, like RTTY contesting or 
WSJT-X modes where high power is needed (6M, 160M, for example)?  If you 
do a lot of meteor scatter or FT8 or moonbounce, especially on 6M where 
the efficiency is lowest, it doesn't take long for the fans to scream. 
And that's because they are small, which they must be to fit in the 
height dimension of the power amp.


73, Jim K9YC


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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[Peter Hall]

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-boun...@mailman.qth.net  On 
Behalf Of eric norris via Elecraft
Sent: Tuesday, 11 June 2019 7:57 AM
To: li...@w2irt.net; li...@w2irt.net; Elecraft Reflector 

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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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[Eric Norris]

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  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-boun...@mailman.qth.net 
> On Behalf Of eric norris via Elecraft
> Sent: Tuesday, 11 June 2019 7:57 AM
> To: li...@w2irt.net; li...@w2irt.net; Elecraft Reflector <
> elecraft@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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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[John Langdon]

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-boun...@mailman.qth.net  On 
Behalf Of Eric Norris
Sent: Tuesday, June 11, 2019 3:47 AM
To: Peter Hall 
Cc: elecraft@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  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-boun...@mailman.qth.net 
> 
> On Behalf Of eric norris via Elecraft
> Sent: Tuesday, 11 June 2019 7:57 AM
> To: li...@w2irt.net; li...@w2irt.net; Elecraft Reflector < 
> elecraft@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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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[Roy Koeppe]

Eric -- this is not at all normal! My PSU is quiet...hardly hear it from 
under the table. I understand Elecraft changed to much quieter fans maybe 
two years ago. But even so, perhaps the voltage to your fans has soared way 
to high? I haven't looked at the circuit driving them. Maybe lost 
regulation, etc.


73,   RoyK6XK


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



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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[Larry (K8UT)]

Eric,

My shack is a relatively quiet operating environment, but declaring 
something as quiet or noisy is always somewhat subjective. The fans in 
my PSU are pretty quiet, but nevertheless the KPA1500 PSU is 
remote-installed in a closet in my shack.


I am absolutely no "audio" guy, but years ago installed a free, cheap & 
dirty noise level meter app on my android phone called "Sound Meter." I 
use it to complain to restaurant managers that the blaring music in 
their establishments is too loud for casual conversation, demanding that 
it be turned down.


With the KPA1500 turned off and phone situated 3 feet from the power 
supply, the noise level in that closet is 28 DB. Turning on the 
amplifier raises the noise level by 12 DB to 40 DB - a 12 DB difference. 
Not much difference, and certainly not the "piercing power supply fan 
noise" you describe.


-larry (K8UT)

-- Original Message --
From: "eric norris via Elecraft" 
To: "li...@w2irt.net" ; "li...@w2irt.net" 
; "Elecraft Reflector" 

Sent: 2019-06-10 19:57:02
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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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[Dan Atchison via Elecraft]

My KPA1500 s/n 156 had such a problem with PS audible noise.?? It was 
fixed with two mods available from Elecraft, one a new LED board and 
another with a resistor addition to the MeanWell power supply output?? 
The latter was probably not associated with noise but it's an addition 
that was not on my #156.


73,
Dan -- N3ND

On 6/11/2019 7:51 AM, Roy Koeppe wrote:
Eric -- this is not at all normal! My PSU is quiet...hardly hear it 
from under the table. I understand Elecraft changed to much quieter 
fans maybe two years ago. But even so, perhaps the voltage to your 
fans has soared way to high? I haven't looked at the circuit driving 
them. Maybe lost regulation, etc.


73, Roy?? K6XK


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



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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[Richard Thorne]

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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[Michael Walker]

How loud is the noise?

Can you measure it at all?  There are many smart phone apps that are really
good.

I compared my iPhone to a bench standard and it was off by less 0.5db at
most frequencies.  Pretty impressive actually.

Mike va3mw


On Tue, Jun 11, 2019 at 9:49 AM Richard Thorne  wrote:

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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[N4ZR]

And my SN 502 is perfectly acceptable, even with the stock fan-ware (is 
that a word?)


73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 6/11/2019 9:22 AM, Dan Atchison via Elecraft wrote:
My KPA1500 s/n 156 had such a problem with PS audible noise.?? It was 
fixed with two mods available from Elecraft, one a new LED board and 
another with a resistor addition to the MeanWell power supply output?? 
The latter was probably not associated with noise but it's an addition 
that was not on my #156.


73,
Dan -- N3ND

On 6/11/2019 7:51 AM, Roy Koeppe wrote:
Eric -- this is not at all normal! My PSU is quiet...hardly hear it 
from under the table. I understand Elecraft changed to much quieter 
fans maybe two years ago. But even so, perhaps the voltage to your 
fans has soared way to high? I haven't looked at the circuit driving 
them. Maybe lost regulation, etc.


73, Roy?? K6XK


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



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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[K9MA]

I suspect the reason the power supply fans run at constant speed is that 
they are part of the Meanwell power supply, and beyond Elecraft's 
control due to warranty issues, etc. I certainly can't fault Elecraft 
for using that power supply, as it's cost effective and probably helped 
get the KPA1500 on the market more quickly. We can hope that perhaps 
some day Meanwell will switch to a temperature controlled fan.


I don't find mine particularly loud, as the RF deck fans drown them out 
even at their lower speeds. Even the K3 fans will drown it out when I'm 
running in a CW contest. I use some very good passive headphones, 
however. I don't think it's realistic to expect to be able to operate 
with an amplifier in the shack without headphones. However, the KPA1500 
is fully capable of remote operation, so you could put it in the next room.


73,
Scott K9MA

On 6/10/2019 18:57, eric norris via Elecraft wrote:

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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--
Scott  K9MA

k...@sdellington.us

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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[exbpi]

Hi Steve,

Thanks for the update.

So, this is the LED board on the amp, not the power supply? Guess we don't
know at what serial number the change was made?

Mike
K7PI


-Original Message-
From: elecraft-boun...@mailman.qth.net  On
Behalf Of STEPHEN R ZUMBRUN
Sent: Saturday, June 27, 2020 16:39
To: elecraft@mailman.qth.net
Subject: [Elecraft] KPA1500 Power Supply Fan Noise

Hello, all and Happy Field Day. Say I just wanted to comment about Elecraft
service and the help they provided me to make a mod to my KPA1500. My
KPA1500 power supply fan was rather noisy. I had seen discussion on the
reflector about this so I contacted Doug at Elecraft service. He ask if I
could solder.  I informed him I could and he sent me a new 22 ohm, 3 watt
resistor and i swapped it out with the 10 ohm, 3 watt resistor on the LED
board of the power supply. I am much pleased with the sound of the power
supply fan now after the modification. My amp is an early serial number and
the new amps come with the 22 ohm resistor on the LED board. So...if your
power supply is a bit noisy you might consider this mod and contact Doug at
Elecraft Service. The Elecraft part number of the resistor is E500128. 73,
Steve W0SZ.
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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[Dave]

It is the LED board in the PS.

Dave wo2x

Sent from my iPad

> On Jun 27, 2020, at 7:55 PM, ex...@comcast.net wrote:
> 
> Hi Steve,
> 
> Thanks for the update.
> 
> So, this is the LED board on the amp, not the power supply? Guess we don't
> know at what serial number the change was made?
> 
> Mike
> K7PI
> 
> 
> -Original Message-
> From: elecraft-boun...@mailman.qth.net  On
> Behalf Of STEPHEN R ZUMBRUN
> Sent: Saturday, June 27, 2020 16:39
> To: elecraft@mailman.qth.net
> Subject: [Elecraft] KPA1500 Power Supply Fan Noise
> 
> Hello, all and Happy Field Day. Say I just wanted to comment about Elecraft
> service and the help they provided me to make a mod to my KPA1500. My
> KPA1500 power supply fan was rather noisy. I had seen discussion on the
> reflector about this so I contacted Doug at Elecraft service. He ask if I
> could solder.  I informed him I could and he sent me a new 22 ohm, 3 watt
> resistor and i swapped it out with the 10 ohm, 3 watt resistor on the LED
> board of the power supply. I am much pleased with the sound of the power
> supply fan now after the modification. My amp is an early serial number and
> the new amps come with the 22 ohm resistor on the LED board. So...if your
> power supply is a bit noisy you might consider this mod and contact Doug at
> Elecraft Service. The Elecraft part number of the resistor is E500128. 73,
> Steve W0SZ.
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Re: [Elecraft] KPA1500 Power Supply Fan Noise

[Steve]

As Dave mentioned the LED board is in the power supply. Take off the cover of 
the power supply and the LED board is small board located on front left side as 
you look at the amp from the rear. It’s held in place by two small screws. The 
resistor to change is located bottom of the board as your looking at it from 
the rear of the amp. The resistor needs to stand off the board a couple of mm. 

Your question regarding the SN when this change occurred is a good one. I don’t 
know the answer. My amp was one of the first with a very low SN. 73

> On Jun 27, 2020, at 6:43 PM, Dave  wrote:
> 
> It is the LED board in the PS.
> 
> Dave wo2x
> 
> Sent from my iPad
> 
>> On Jun 27, 2020, at 7:55 PM, ex...@comcast.net wrote:
>> 
>> Hi Steve,
>> 
>> Thanks for the update.
>> 
>> So, this is the LED board on the amp, not the power supply? Guess we don't
>> know at what serial number the change was made?
>> 
>> Mike
>> K7PI
>> 
>> 
>> -Original Message-
>> From: elecraft-boun...@mailman.qth.net  On
>> Behalf Of STEPHEN R ZUMBRUN
>> Sent: Saturday, June 27, 2020 16:39
>> To: elecraft@mailman.qth.net
>> Subject: [Elecraft] KPA1500 Power Supply Fan Noise
>> 
>> Hello, all and Happy Field Day. Say I just wanted to comment about Elecraft
>> service and the help they provided me to make a mod to my KPA1500. My
>> KPA1500 power supply fan was rather noisy. I had seen discussion on the
>> reflector about this so I contacted Doug at Elecraft service. He ask if I
>> could solder.  I informed him I could and he sent me a new 22 ohm, 3 watt
>> resistor and i swapped it out with the 10 ohm, 3 watt resistor on the LED
>> board of the power supply. I am much pleased with the sound of the power
>> supply fan now after the modification. My amp is an early serial number and
>> the new amps come with the 22 ohm resistor on the LED board. So...if your
>> power supply is a bit noisy you might consider this mod and contact Doug at
>> Elecraft Service. The Elecraft part number of the resistor is E500128. 73,
>> Steve W0SZ.
>> __
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>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>> delivered to ex...@comcast.net 
>> 
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