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KPA500 Noise While Off

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Richard Wade

KPA500 Noise While Off

Yesterday I heard a faint "hum" in my shack but all of my gear was off. It
sounded like possibly a fan running or power supply noise. I did a very
scientific test of the sound source by putting my ear to each piece of
equipment in my shack and soon found that the noise was coming from my
KPA500! The amplifier was off but was still connected to the shack ac
power. I then removed the power cord from the KPA500 and the noise
disappeared. Does anyone have any idea how this could happen?

By way of further background, I have been dealing with QRN from a recently
installed solar system. I have traced the source of that noise to the
solar system by confirming that the QRN goes away when the solar system is
turned off while running my K3s on battery power.

If I had to venture a guess, I would say that somehow the unpowered KPA500
was picking up noise on the shack wiring. Very strange. Is that possible??

Dick, WM6G
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Bob McGraw - K4TAX

Re: KPA500 Noise While Off

Although the front panel switch is OFF, the control circuit of the power
supply remains ON as long as the rear power switch is ON or power is
applied. It is normal to hear a small amount of hum from the power
transformer and the left rear of the cabinet to be slightly warm. See
page 14 of the KPA500 manual for more detail.

73

Bob, K4TAX

On 6/27/2018 12:37 PM, Richard Wade wrote:

> Yesterday I heard a faint "hum" in my shack but all of my gear was off. It
> sounded like possibly a fan running or power supply noise. I did a very
> scientific test of the sound source by putting my ear to each piece of
> equipment in my shack and soon found that the noise was coming from my
> KPA500! The amplifier was off but was still connected to the shack ac
> power. I then removed the power cord from the KPA500 and the noise
> disappeared. Does anyone have any idea how this could happen?
>
> By way of further background, I have been dealing with QRN from a recently
> installed solar system. I have traced the source of that noise to the
> solar system by confirming that the QRN goes away when the solar system is
> turned off while running my K3s on battery power.
>
> If I had to venture a guess, I would say that somehow the unpowered KPA500
> was picking up noise on the shack wiring. Very strange. Is that possible??
>
> Dick, WM6G
> ______________________________________________________________
> Elecraft mailing list
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Ken Winterling

Re: KPA500 Noise While Off

In reply to this post by Richard Wade

Dick,

The KPA500 has a power supply switch on the rear panel adjacent to the
socket for the power cord. When you press the OFF button on the front
panel the control circuitry is still active. This permits software to
remotely power up the amp. If you turn off that rear switch all power is
removed from the amp; the same as pulling the plug from the wall socket.

Ken
WA2LBI

On Wed, Jun 27, 2018 at 13:38 Richard Wade <[hidden email]> wrote:

--

Ken
WA2LBI

Sent from one of my mobile devices
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Jim Brown-10

Re: KPA500 Noise While Off

In reply to this post by Richard Wade

On 6/27/2018 10:37 AM, Richard Wade wrote:
> If I had to venture a guess, I would say that somehow the unpowered KPA500
> was picking up noise on the shack wiring. Very strange. Is that possible??

It is if equipment in your shack is not properly bonded together, and to
house grounds that are also properly bonded together. Study N0AX's
recent ARRL book on the topic, to which I contributed, or the slides for
a tutorial talk I've done at several hamfests.

http://k9yc.com/GroundingAndAudio.pdf

73, Jim K9YC

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Matt Murphy

Re: KPA500 Noise While Off

My KPA500 makes a noticeable hum/thump when the laser printer that is on
the same circuit draws a lot of current.

73,
Matt NQ6N

On Wed, Jun 27, 2018 at 12:58 PM Jim Brown <[hidden email]>
wrote:

> On 6/27/2018 10:37 AM, Richard Wade wrote:
> > If I had to venture a guess, I would say that somehow the unpowered
> KPA500
> > was picking up noise on the shack wiring. Very strange. Is that
> possible??
>
> It is if equipment in your shack is not properly bonded together, and to
> house grounds that are also properly bonded together. Study N0AX's
> recent ARRL book on the topic, to which I contributed, or the slides for
> a tutorial talk I've done at several hamfests.
>
> http://k9yc.com/GroundingAndAudio.pdf
>
> 73, Jim K9YC
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

John Simmons

Re: KPA500 Noise While Off

My Astron RS35 does the same thing under the same conditions.

-John NI0K

Matt NQ6N wrote on 6/27/2018 1:20 PM:

> My KPA500 makes a noticeable hum/thump when the laser printer that is on
> the same circuit draws a lot of current.
>
> 73,
> Matt NQ6N
>
> On Wed, Jun 27, 2018 at 12:58 PM Jim Brown <[hidden email]>
> wrote:
>
>> On 6/27/2018 10:37 AM, Richard Wade wrote:
>>> If I had to venture a guess, I would say that somehow the unpowered
>> KPA500
>>> was picking up noise on the shack wiring. Very strange. Is that
>> possible??
>>
>> It is if equipment in your shack is not properly bonded together, and to
>> house grounds that are also properly bonded together. Study N0AX's
>> recent ARRL book on the topic, to which I contributed, or the slides for
>> a tutorial talk I've done at several hamfests.
>>
>> http://k9yc.com/GroundingAndAudio.pdf
>>
>> 73, Jim K9YC
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
> ______________________________________________________________
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>
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Bob McGraw - K4TAX

Re: KPA500 Noise While Off

Seems that the AC line supplying the equipment has a rather high impedance thus allowing the voltage to suddenly drop under the dynamic load and then surge to a higher than normal value.

A dedicated 120V and/or 240V service should be considered for the station power.

Laser printers do draw considerable power when they start.

Bob, K4TAX

Sent from my iPhone

> On Jun 27, 2018, at 2:00 PM, John Simmons <[hidden email]> wrote:
>
> My Astron RS35 does the same thing under the same conditions.
>
> -John NI0K
>
> Matt NQ6N wrote on 6/27/2018 1:20 PM:
>> My KPA500 makes a noticeable hum/thump when the laser printer that is on
>> the same circuit draws a lot of current.
>>
>> 73,
>> Matt NQ6N
>>
>> On Wed, Jun 27, 2018 at 12:58 PM Jim Brown <[hidden email]>
>> wrote:
>>
>>>> On 6/27/2018 10:37 AM, Richard Wade wrote:
>>>> If I had to venture a guess, I would say that somehow the unpowered
>>> KPA500
>>>> was picking up noise on the shack wiring. Very strange. Is that
>>> possible??
>>>
>>> It is if equipment in your shack is not properly bonded together, and to
>>> house grounds that are also properly bonded together. Study N0AX's
>>> recent ARRL book on the topic, to which I contributed, or the slides for
>>> a tutorial talk I've done at several hamfests.
>>>
>>> http://k9yc.com/GroundingAndAudio.pdf
>>>
>>> 73, Jim K9YC
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>>>
>> ______________________________________________________________
>> Elecraft mailing list
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>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>
> ______________________________________________________________
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>
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ke9uw

Re: KPA500 Noise While Off

I’ve only noticed a thump with a piece of equipment which has a power supply when it turns on at a line voltage peak. On the occasion that it turns on at a line voltage zero crossing, it makes no noise at all.

Chuck
KE9UW

Sent from my iPhone, cjack

> On Jun 27, 2018, at 2:10 PM, Bob McGraw K4TAX <[hidden email]> wrote:
>
> Seems that the AC line supplying the equipment has a rather high impedance thus allowing the voltage to suddenly drop under the dynamic load and then surge to a higher than normal value.
>
> A dedicated 120V and/or 240V service should be considered for the station power.
>
> Laser printers do draw considerable power when they start.
>
> Bob, K4TAX
>
>
> Sent from my iPhone
>
>> On Jun 27, 2018, at 2:00 PM, John Simmons <[hidden email]> wrote:
>>
>> My Astron RS35 does the same thing under the same conditions.
>>
>> -John NI0K
>>
>> Matt NQ6N wrote on 6/27/2018 1:20 PM:
>>> My KPA500 makes a noticeable hum/thump when the laser printer that is on
>>> the same circuit draws a lot of current.
>>>
>>> 73,
>>> Matt NQ6N
>>>
>>> On Wed, Jun 27, 2018 at 12:58 PM Jim Brown <[hidden email]>
>>> wrote:
>>>
>>>>> On 6/27/2018 10:37 AM, Richard Wade wrote:
>>>>> If I had to venture a guess, I would say that somehow the unpowered
>>>> KPA500
>>>>> was picking up noise on the shack wiring. Very strange. Is that
>>>> possible??
>>>>
>>>> It is if equipment in your shack is not properly bonded together, and to
>>>> house grounds that are also properly bonded together. Study N0AX's
>>>> recent ARRL book on the topic, to which I contributed, or the slides for
>>>> a tutorial talk I've done at several hamfests.
>>>>
>>>> http://k9yc.com/GroundingAndAudio.pdf
>>>>
>>>> 73, Jim K9YC
>>>>
>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to [hidden email]
>>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>>
>
>
> ______________________________________________________________
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Chuck, KE9UW

Bob McGraw - K4TAX

Re: KPA500 Noise While Off

Yes that is the magnetization current of the transformer core.
Doesn't happen when powered up at the zero voltage crossing point.

One person advised to always turn on equipment at the zero crossing point. Seems like a good idea. Now if I could only get my finger timed correctly to do this.

Bob, K4TAX

Sent from my iPhone

> On Jun 27, 2018, at 2:42 PM, hawley, charles j jr <[hidden email]> wrote:
>
> I’ve only noticed a thump with a piece of equipment which has a power supply when it turns on at a line voltage peak. On the occasion that it turns on at a line voltage zero crossing, it makes no noise at all.
>
> Chuck
> KE9UW
>
> Sent from my iPhone, cjack
>
>> On Jun 27, 2018, at 2:10 PM, Bob McGraw K4TAX <[hidden email]> wrote:
>>
>> Seems that the AC line supplying the equipment has a rather high impedance thus allowing the voltage to suddenly drop under the dynamic load and then surge to a higher than normal value.
>>
>> A dedicated 120V and/or 240V service should be considered for the station power.
>>
>> Laser printers do draw considerable power when they start.
>>
>> Bob, K4TAX
>>
>>
>> Sent from my iPhone
>>
>>> On Jun 27, 2018, at 2:00 PM, John Simmons <[hidden email]> wrote:
>>>
>>> My Astron RS35 does the same thing under the same conditions.
>>>
>>> -John NI0K
>>>
>>> Matt NQ6N wrote on 6/27/2018 1:20 PM:
>>>> My KPA500 makes a noticeable hum/thump when the laser printer that is on
>>>> the same circuit draws a lot of current.
>>>>
>>>> 73,
>>>> Matt NQ6N
>>>>
>>>> On Wed, Jun 27, 2018 at 12:58 PM Jim Brown <[hidden email]>
>>>> wrote:
>>>>
>>>>>> On 6/27/2018 10:37 AM, Richard Wade wrote:
>>>>>> If I had to venture a guess, I would say that somehow the unpowered
>>>>> KPA500
>>>>>> was picking up noise on the shack wiring. Very strange. Is that
>>>>> possible??
>>>>>
>>>>> It is if equipment in your shack is not properly bonded together, and to
>>>>> house grounds that are also properly bonded together. Study N0AX's
>>>>> recent ARRL book on the topic, to which I contributed, or the slides for
>>>>> a tutorial talk I've done at several hamfests.
>>>>>
>>>>> http://k9yc.com/GroundingAndAudio.pdf
>>>>>
>>>>> 73, Jim K9YC
>>>>>
>>>>>
>>>>> ______________________________________________________________
>>>>> Elecraft mailing list
>>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>>> Post: mailto:[hidden email]
>>>>>
>>>>> This list hosted by: http://www.qsl.net
>>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>> Message delivered to [hidden email]
>>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to [hidden email]
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>>>
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>

chrisrut

Re: KPA500 Noise While Off

In reply to this post by Richard Wade

I may be wrong, but that may not be what Dick, WM6G, is referring to.

I've had a KPA500 for quite some time, so I have an idea of what
constitutes "normal."

In the last few months I've noticed that every morning, between roughly
9-10 AM, I hear brief 1-5 second pulsations of easily audible hum emanating
from the KPA500. The pulsing events last perhaps 30 seconds to a minute,
and may happen more than once.

Yes, this ceases if the power cord is out or the power switch on the rear
is OFF. But again, it is brief-lived when it occurs, and it's new.

To me, guessing, it sounds like something connected to the main AC feed is
coming up out of phase, then finally syncing, after which the hum stops.

A neighbor's solar array? I have no idea as of this point.

73 Chris NW6V

>Message: 23
>Date: Wed, 27 Jun 2018 12:48:19 -0500
>From: Bob McGraw K4TAX <[hidden email]>
>To: [hidden email]
>Subject: Re: [Elecraft] KPA500 Noise While Off
>Message-ID: <[hidden email]>
>Content-Type: text/plain; charset=utf-8; format=flowed
>
>Although the front panel switch is OFF, the control circuit of the power
>supply remains ON as long as the rear power switch is ON or power is
>applied.? It is normal to hear a small amount of hum from the power
>transformer and the left rear of the cabinet to be slightly warm.? See
>page 14 of the KPA500 manual for more detail.>
>
>73
>Bob, K4TAX

ke9uw

Re: KPA500 Noise While Off

In reply to this post by Bob McGraw - K4TAX

Triac switch would do it. Seems like a natural for equipment but seldom used.

Chuck Jack
KE9UW

Sent from my iPhone, cjack

> On Jun 27, 2018, at 2:54 PM, Bob McGraw K4TAX <[hidden email]> wrote:
>
> Yes that is the magnetization current of the transformer core.
> Doesn't happen when powered up at the zero voltage crossing point.
>
> One person advised to always turn on equipment at the zero crossing point. Seems like a good idea. Now if I could only get my finger timed correctly to do this.
>
> Bob, K4TAX
>
>
> Sent from my iPhone
>
>> On Jun 27, 2018, at 2:42 PM, hawley, charles j jr <[hidden email]> wrote:
>>
>> I’ve only noticed a thump with a piece of equipment which has a power supply when it turns on at a line voltage peak. On the occasion that it turns on at a line voltage zero crossing, it makes no noise at all.
>>
>> Chuck
>> KE9UW
>>
>> Sent from my iPhone, cjack
>>
>>> On Jun 27, 2018, at 2:10 PM, Bob McGraw K4TAX <[hidden email]> wrote:
>>>
>>> Seems that the AC line supplying the equipment has a rather high impedance thus allowing the voltage to suddenly drop under the dynamic load and then surge to a higher than normal value.
>>>
>>> A dedicated 120V and/or 240V service should be considered for the station power.
>>>
>>> Laser printers do draw considerable power when they start.
>>>
>>> Bob, K4TAX
>>>
>>>
>>> Sent from my iPhone
>>>
>>>> On Jun 27, 2018, at 2:00 PM, John Simmons <[hidden email]> wrote:
>>>>
>>>> My Astron RS35 does the same thing under the same conditions.
>>>>
>>>> -John NI0K
>>>>
>>>> Matt NQ6N wrote on 6/27/2018 1:20 PM:
>>>>> My KPA500 makes a noticeable hum/thump when the laser printer that is on
>>>>> the same circuit draws a lot of current.
>>>>>
>>>>> 73,
>>>>> Matt NQ6N
>>>>>
>>>>> On Wed, Jun 27, 2018 at 12:58 PM Jim Brown <[hidden email]>
>>>>> wrote:
>>>>>
>>>>>>> On 6/27/2018 10:37 AM, Richard Wade wrote:
>>>>>>> If I had to venture a guess, I would say that somehow the unpowered
>>>>>> KPA500
>>>>>>> was picking up noise on the shack wiring. Very strange. Is that
>>>>>> possible??
>>>>>>
>>>>>> It is if equipment in your shack is not properly bonded together, and to
>>>>>> house grounds that are also properly bonded together. Study N0AX's
>>>>>> recent ARRL book on the topic, to which I contributed, or the slides for
>>>>>> a tutorial talk I've done at several hamfests.
>>>>>>
>>>>>> http://k9yc.com/GroundingAndAudio.pdf
>>>>>>
>>>>>> 73, Jim K9YC
>>>>>>
>>>>>>
>>>>>> ______________________________________________________________
>>>>>> Elecraft mailing list
>>>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>>>> Post: mailto:[hidden email]
>>>>>>
>>>>>> This list hosted by: http://www.qsl.net
>>>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>>> Message delivered to [hidden email]
>>>>>>
>>>>> ______________________________________________________________
>>>>> Elecraft mailing list
>>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>>> Post: mailto:[hidden email]
>>>>>
>>>>> This list hosted by: http://www.qsl.net
>>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>> Message delivered to [hidden email]
>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:[hidden email]
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>> Message delivered to [hidden email]
>>>>
>>>
>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:[hidden email]
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to [hidden email]
>>
>
>

Chuck, KE9UW

Bob McGraw - K4TAX

Re: KPA500 Noise While Off

In reply to this post by chrisrut

It would seem prudent to install a recording power line monitor. This would give a clue if further line conditioning would be advantageous. Your power company may be able to assist in this matter.

Bob, K4TAX

Sent from my iPhone

> On Jun 27, 2018, at 3:00 PM, Chris R. NW6V <[hidden email]> wrote:
>
> I may be wrong, but that may not be what Dick, WM6G, is referring to.
>
> I've had a KPA500 for quite some time, so I have an idea of what
> constitutes "normal."
>
> In the last few months I've noticed that every morning, between roughly
> 9-10 AM, I hear brief 1-5 second pulsations of easily audible hum emanating
> from the KPA500. The pulsing events last perhaps 30 seconds to a minute,
> and may happen more than once.
>
> Yes, this ceases if the power cord is out or the power switch on the rear
> is OFF. But again, it is brief-lived when it occurs, and it's new.
>
> To me, guessing, it sounds like something connected to the main AC feed is
> coming up out of phase, then finally syncing, after which the hum stops.
>
> A neighbor's solar array? I have no idea as of this point.
>
> 73 Chris NW6V
>
>
>> Message: 23
>> Date: Wed, 27 Jun 2018 12:48:19 -0500
>> From: Bob McGraw K4TAX <[hidden email]>
>> To: [hidden email]
>> Subject: Re: [Elecraft] KPA500 Noise While Off
>> Message-ID: <[hidden email]>
>> Content-Type: text/plain; charset=utf-8; format=flowed
>>
>> Although the front panel switch is OFF, the control circuit of the power
>> supply remains ON as long as the rear power switch is ON or power is
>> applied.? It is normal to hear a small amount of hum from the power
>> transformer and the left rear of the cabinet to be slightly warm.? See
>> page 14 of the KPA500 manual for more detail.>
>>
>> 73
>> Bob, K4TAX
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

k6dgw

Re: KPA500 Noise While Off

In reply to this post by chrisrut

Perhaps this is because none of us actually inspect our electricity
before buying it? I don't inspect the gasoline I buy either, and by the
time it's in the tank in my truck, I've already bought it. [:-)

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 6/27/2018 1:00 PM, Chris R. NW6V wrote:

> I may be wrong, but that may not be what Dick, WM6G, is referring to.
>
> I've had a KPA500 for quite some time, so I have an idea of what
> constitutes "normal."
>
> In the last few months I've noticed that every morning, between roughly
> 9-10 AM, I hear brief 1-5 second pulsations of easily audible hum emanating
> from the KPA500. The pulsing events last perhaps 30 seconds to a minute,
> and may happen more than once.
>
> Yes, this ceases if the power cord is out or the power switch on the rear
> is OFF. But again, it is brief-lived when it occurs, and it's new.
>
> To me, guessing, it sounds like something connected to the main AC feed is
> coming up out of phase, then finally syncing, after which the hum stops.
>
> A neighbor's solar array? I have no idea as of this point.
>
> 73 Chris NW6V
>

Jim Brown-10

Re: KPA500 Noise While Off

In reply to this post by Bob McGraw - K4TAX

On 6/27/2018 1:33 PM, Bob McGraw K4TAX wrote:
> This would give a clue if further line conditioning would be advantageous.

I'm certain that some charlatan preying on high futility nuts would be
quite happy to lighten his bank account by at least as much as he paid
for the KPA500. These products provide no benefit to audio consumers,
and they would provide no benefit in a ham station. Their only function
is to transfer money from the buyer to the seller.

None of what's being discussed here should be a problem, and the easiest
ways to minimize the symptoms are 1) to simply beef up the wiring
between the power amp and the distro panel, or 2) shorten the wiring, or
3) provide a breaker dedicated to the shack. A single 15A circuit should
run all the RADIO equipment in the shack where the power amp is a
KPA500. Obviously, a 20A circuit provides more margin, bigger copper and
shorter copper reduce IR drop.

For the printer, as others have noted, the IR drop between it and the
breaker panel for the turn-on surge, so bigger copper for that part of
the run would also have to be replaced.

And yes, a solar array syncing could easily be the cause of that
9AM-10AM event reported by NW6V.

73, Jim K9YC

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