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Hum on KPA1500

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Carl Yaffey-2

Hum on KPA1500

I have developed a loud hum with the KPA1500 on 17m and 15m. A slight hum on 20m. All other bands, no hum.
It’s power dependent. Loud at full power, hum reduces as power is lowered. Not too bad at 500w.
Suggestions?
73.

Carl, K8NU.
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Ken Winterling

Re: Hum on KPA1500

Carl,

Does this also happen when directly connected to a dummy load? If not then
maybe you have an RFI problem. Check all antenna connections and jumpers.

GL!

Ken
WA2LBI

On Sun, Apr 5, 2020 at 4:51 PM Carl Yaffey <[hidden email]> wrote:

> I have developed a loud hum with the KPA1500 on 17m and 15m. A slight hum
> on 20m. All other bands, no hum.
> It’s power dependent. Loud at full power, hum reduces as power is lowered.
> Not too bad at 500w.
> Suggestions?
> 73.
>
> Carl, K8NU.
>
>

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David Gilbert

Re: Hum on KPA1500

In reply to this post by Carl Yaffey-2

You'd probably get more useful replies if you mentioned whether the hum
was in your transmitted signal or was audio hum in the shack.

Dave AB7E

On 4/5/2020 1:50 PM, Carl Yaffey wrote:
> I have developed a loud hum with the KPA1500 on 17m and 15m. A slight hum on 20m. All other bands, no hum.
> It’s power dependent. Loud at full power, hum reduces as power is lowered. Not too bad at 500w.
> Suggestions?
> 73.
>
> Carl, K8NU.

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Carl Yaffey-2

Re: Hum on KPA1500

In reply to this post by Ken Winterling

Just tried a dummy load. No hum. So must be RF. On to the hunt!
Thanks, folks.
Carl K8NU

> On Apr 5, 2020, at 4:59 PM, Ken Winterling <[hidden email]> wrote:
>
> Carl,
>
> Does this also happen when directly connected to a dummy load? If not then maybe you have an RFI problem. Check all antenna connections and jumpers.
>
> GL!
>
> Ken
> WA2LBI
>
>
>
> On Sun, Apr 5, 2020 at 4:51 PM Carl Yaffey <[hidden email] <mailto:[hidden email]>> wrote:
> I have developed a loud hum with the KPA1500 on 17m and 15m. A slight hum on 20m. All other bands, no hum.
> It’s power dependent. Loud at full power, hum reduces as power is lowered. Not too bad at 500w.
> Suggestions?
> 73.
>
> Carl, K8NU.
>

Salvatore Ted K2QMF

Re: Hum on KPA1500

In reply to this post by Carl Yaffey-2

From the Power Supply or KPA1500?? Or Both??

On 4/5/2020 5:03:51 PM, Carl Yaffey <[hidden email]> wrote:
Hum is in the shack.

On Apr 5, 2020, at 4:58 PM, Salvatore Ted K2QMF <[hidden email] [mailto:[hidden email]]> wrote:

Hum on your Transmit Signal??
Or hum in the shack??
Where is the hum coming from??

On 4/5/2020 4:51:23 PM, Carl Yaffey <[hidden email] [mailto:[hidden email]]> wrote:
I have developed a loud hum with the KPA1500 on 17m and 15m. A slight hum on 20m. All other bands, no hum.
It’s power dependent. Loud at full power, hum reduces as power is lowered. Not too bad at 500w.
Suggestions?
73.

Carl, K8NU.
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Jim Brown-10

Re: Hum on KPA1500

In reply to this post by Carl Yaffey-2

On 4/5/2020 1:50 PM, Carl Yaffey wrote:
> I have developed a loud hum with the KPA1500 on 17m and 15m. A slight hum on 20m. All other bands, no hum.

Because it's frequency dependent, I suspect some form of RFI. Start by
making sure that everything in your station is properly bonded.
http://k9yc.com/GroundingAndAudio.pdf

If that doesn't fix it, add ferrite chokes as described in
http://k9yc.com/KillingReceiveNoise.pdf

While the second reference is about killing RX noise, the same
principles apply to the problem you're having.

But do the bonding first.

One question though -- is what you hear HUM (pure 60 Hz) or BUZZ
(triplen harmonics of 60 Hz, like 180, 360, 540, etc)?

73, Jim K9YC
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Frank O'Donnell

Re: Hum on KPA1500

I'm not the OP, but can you remind us what buzz (multiple harmonics of
60 Hz) might signify?

Thanks,

Frank K6FOD

On 4/5/20 4:13 PM, Jim Brown wrote:
> One question though -- is what you hear HUM (pure 60 Hz) or BUZZ
> (triplen harmonics of 60 Hz, like 180, 360, 540, etc)?

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Bob McGraw - K4TAX

Re: Hum on KPA1500

In reply to this post by Carl Yaffey-2

I find it interesting where it is stated "I have developed a loud
hum........" which would imply the hum did not exist prior to this point
of observation.   That being the case, then one must ask "Ok so what has
changed, been added or removed?".   If it wasn't there before and
nothing has been changed, then why is it there now?    Something has
failed, connections have corroded or broken, PL-259's is not tight, coax
jumper has failed due to movement. Thus I would suggest one find the
problem and correct the problem.   I see no value and no point in adding
to or re-designing a system which previously worked correctly.

Now, if something was indeed added, removed or changed, that opens up
another area for investigation.   What was not done correctly to
accommodate the new configuration?

Jim, K9YC has some good points on bonding, grounding and proper use of
chokes.

73

Bob, K4TAX

On 4/5/2020 3:50 PM, Carl Yaffey wrote:

> I have developed a loud hum with the KPA1500 on 17m and 15m. A slight hum on 20m. All other bands, no hum.
> It’s power dependent. Loud at full power, hum reduces as power is lowered. Not too bad at 500w.
> Suggestions?
> 73.
>
> Carl, K8NU.
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Jim Brown-10

Re: Hum on KPA1500

In reply to this post by Frank O'Donnell

On 4/5/2020 5:16 PM, Frank O'Donnell wrote:
> I'm not the OP, but can you remind us what buzz (multiple harmonics of
> 60 Hz) might signify?

60 Hz hum is nearly always magnetic coupling in some form; buzz is
generated in the three phase power systems used to distribute power.
While few of us have 3-phase power in our homes, the systems out on the
street ARE 3-phase. These harmonics are present because a very large
fraction of the loads on the power system are some form of
rectifier-capacitor-input power supply; most of the AC load current
flows at the positive and negative peaks of the 60 Hz sine wave to
recharge the filter cap. This causes the current waveform to be a
series of positive and negative pulses, and the IR drop causes the top
of the voltage waveform to be rounded off. And we know that any
distorted signal is composed of harmonics.

In an ideally balanced three-phase system with only sine-wave loads, the
neutral current goes to zero. But when harmonics are present (the
distortion), harmonics whose number is divisible by 3 ADD in the neutral
rather than cancel. They also add in the ground!

Buzz is generated by leakage current in the power system; it can couple
into our equipment by a couple of mechanisms. It can be eliminated by 1)
proper bonding within our home and station; and 2) getting power for all
station equipment, including computers and other accessories, from the
same AC outlet, or from outlets whose green wires are bonded together.
All of this is addressed in the slide deck for tutorial talks I've done
at Pacificon, Visalia, and to several ham clubs.

http://k9yc.com/GroundingAndAudio.pdf

73, Jim K9YC
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David Christ

Re: Hum on KPA1500

That I understand but if the ground from the entrance breaker panel to a water pipe from the street is 30 feet long, can it radiate interference to AM radios near it (both AC and battery powered)? If so could it cause RFI at even higher frequencies?

David K0LUM

> On Apr 5, 2020, at 10:35 PM, Jim Brown <[hidden email]> wrote:
>
> On 4/5/2020 5:16 PM, Frank O'Donnell wrote:
>> I'm not the OP, but can you remind us what buzz (multiple harmonics of 60 Hz) might signify?
>
> 60 Hz hum is nearly always magnetic coupling in some form; buzz is generated in the three phase power systems used to distribute power. While few of us have 3-phase power in our homes, the systems out on the street ARE 3-phase. These harmonics are present because a very large fraction of the loads on the power system are some form of rectifier-capacitor-input power supply; most of the AC load current flows at the positive and negative peaks of the 60 Hz sine wave to recharge the filter cap. This causes the current waveform to be a series of positive and negative pulses, and the IR drop causes the top of the voltage waveform to be rounded off. And we know that any distorted signal is composed of harmonics.
>
> In an ideally balanced three-phase system with only sine-wave loads, the neutral current goes to zero. But when harmonics are present (the distortion), harmonics whose number is divisible by 3 ADD in the neutral rather than cancel. They also add in the ground!
>
> Buzz is generated by leakage current in the power system; it can couple into our equipment by a couple of mechanisms. It can be eliminated by 1) proper bonding within our home and station; and 2) getting power for all station equipment, including computers and other accessories, from the same AC outlet, or from outlets whose green wires are bonded together. All of this is addressed in the slide deck for tutorial talks I've done at Pacificon, Visalia, and to several ham clubs.
>
> http://k9yc.com/GroundingAndAudio.pdf
>
> 73, Jim K9YC
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Clay Autery-2

Re: Hum on KPA1500

NO "water pipe" should ever be used as a service ground... I thought
the code was changed to actually bar that practice entirely.

______________________
Clay Autery, KY5G
(318) 518-1389

On 04/05/20 23:06, David Christ wrote:

> That I understand but if the ground from the entrance breaker panel to a water pipe from the street is 30 feet long, can it radiate interference to AM radios near it (both AC and battery powered)? If so could it cause RFI at even higher frequencies?
>
> David K0LUM
>
>> On Apr 5, 2020, at 10:35 PM, Jim Brown <[hidden email]> wrote:
>>
>> On 4/5/2020 5:16 PM, Frank O'Donnell wrote:
>>> I'm not the OP, but can you remind us what buzz (multiple harmonics of 60 Hz) might signify?
>> 60 Hz hum is nearly always magnetic coupling in some form; buzz is generated in the three phase power systems used to distribute power. While few of us have 3-phase power in our homes, the systems out on the street ARE 3-phase. These harmonics are present because a very large fraction of the loads on the power system are some form of rectifier-capacitor-input power supply; most of the AC load current flows at the positive and negative peaks of the 60 Hz sine wave to recharge the filter cap. This causes the current waveform to be a series of positive and negative pulses, and the IR drop causes the top of the voltage waveform to be rounded off. And we know that any distorted signal is composed of harmonics.
>>
>> In an ideally balanced three-phase system with only sine-wave loads, the neutral current goes to zero. But when harmonics are present (the distortion), harmonics whose number is divisible by 3 ADD in the neutral rather than cancel. They also add in the ground!
>>
>> Buzz is generated by leakage current in the power system; it can couple into our equipment by a couple of mechanisms. It can be eliminated by 1) proper bonding within our home and station; and 2) getting power for all station equipment, including computers and other accessories, from the same AC outlet, or from outlets whose green wires are bonded together. All of this is addressed in the slide deck for tutorial talks I've done at Pacificon, Visalia, and to several ham clubs.
>>
>> http://k9yc.com/GroundingAndAudio.pdf
>>
>> 73, Jim K9YC

David Christ

Re: Hum on KPA1500

It is not just to the water pipe (on the street side of the meter). To get to the pipe it appears to run through 25 feet of garage floor. This I assume was done to create a Ufer ground. Whether the connection to the water feed was intended as a service ground is unknown. It may be to ensure that the interior piping (which is copper) is at the same level as the neutral and ground (green) wires in the electrical system. And yes there is a jumper across the meter.

To complete the picture the neighborhood electrical distribution system is underground and the step down transformer is 100 feet away or more.

I will admit the original post may have been misleading. But we are grasping at straws why the AM radio in the car works fine in the driveway, but as soon as one starts to enter the garage, reception is covered up by a loud growl of static. Radios in a room adjacent to the garage also have a problem while AM radios at the other end of the house are fine. Until I solve this one I will not be able to complete killing all the noise in the house.

David K0LUM

> On Apr 6, 2020, at 12:51 AM, Clay Autery <[hidden email]> wrote:
>
> NO "water pipe" should ever be used as a service ground... I thought the code was changed to actually bar that practice entirely.
>
> ______________________
> Clay Autery, KY5G
> (318) 518-1389
>
> On 04/05/20 23:06, David Christ wrote:
>> That I understand but if the ground from the entrance breaker panel to a water pipe from the street is 30 feet long, can it radiate interference to AM radios near it (both AC and battery powered)? If so could it cause RFI at even higher frequencies?
>>
>> David K0LUM
>>
>>> On Apr 5, 2020, at 10:35 PM, Jim Brown <[hidden email]> wrote:
>>>
>>> On 4/5/2020 5:16 PM, Frank O'Donnell wrote:
>>>> I'm not the OP, but can you remind us what buzz (multiple harmonics of 60 Hz) might signify?
>>> 60 Hz hum is nearly always magnetic coupling in some form; buzz is generated in the three phase power systems used to distribute power. While few of us have 3-phase power in our homes, the systems out on the street ARE 3-phase. These harmonics are present because a very large fraction of the loads on the power system are some form of rectifier-capacitor-input power supply; most of the AC load current flows at the positive and negative peaks of the 60 Hz sine wave to recharge the filter cap. This causes the current waveform to be a series of positive and negative pulses, and the IR drop causes the top of the voltage waveform to be rounded off. And we know that any distorted signal is composed of harmonics.
>>>
>>> In an ideally balanced three-phase system with only sine-wave loads, the neutral current goes to zero. But when harmonics are present (the distortion), harmonics whose number is divisible by 3 ADD in the neutral rather than cancel. They also add in the ground!
>>>
>>> Buzz is generated by leakage current in the power system; it can couple into our equipment by a couple of mechanisms. It can be eliminated by 1) proper bonding within our home and station; and 2) getting power for all station equipment, including computers and other accessories, from the same AC outlet, or from outlets whose green wires are bonded together. All of this is addressed in the slide deck for tutorial talks I've done at Pacificon, Visalia, and to several ham clubs.
>>>
>>> http://k9yc.com/GroundingAndAudio.pdf
>>>
>>> 73, Jim K9YC
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Wes Stewart-2

Re: Hum on KPA1500

In reply to this post by Clay Autery-2

I believe that is the case. However, one point on the water piping should be
bonded to the service ground for safety reasons. Using the piping for
current-carrying purposes is a really bad idea. Keywords: Copper pipe, dirt,
concrete slab, jackhammer. Don't ask me how I know.

Wes N7WS

On 4/5/2020 10:51 PM, Clay Autery wrote:
> NO "water pipe" should ever be used as a service ground... I thought the code
> was changed to actually bar that practice entirely.
>
> ______________________
> Clay Autery, KY5G
> (318) 518-1389

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David Christ

Re: Hum on KPA1500

That is exactly what appears to be happening. Heavy cable starts at service panel, proceeds into floor slab of garage which I assume is acting as Ufer ground. What appears to be the same cable emerges from the other side of the slab and connects to the water system. I think that it is fair to assume that that the cable emerging from the slab is also connected to the Ufer ground thus bonding the water system to the service system ground. This is one of those things that is difficult to unambiguously describe with words but so easily described with a very simple drawing.

I have do doubts that the system was properly designed and safe. But we are getting off the question that I had about RFI. On 3/4/2020 K9YC discussed triplen harmonics in ground systems (I may not be stating it properly). The question is then “Could triplen currents in the power ground system as described be causing the interference I experience when entering my garage?” or is there another explanation for the RFI?

I repeat the description

The AM radio in the car works fine in the driveway, but as soon as one starts to enter the garage, reception is covered up by a loud growl of static. Radios in a room adjacent to the garage and over the cable in the basement below also have a problem while AM radios at the other end of the house are fine.

David K0LUM

> On Apr 6, 2020, at 8:39 AM, Wes <[hidden email]> wrote:
>
> I believe that is the case. However, one point on the water piping should be bonded to the service ground for safety reasons. Using the piping for current-carrying purposes is a really bad idea. Keywords: Copper pipe, dirt, concrete slab, jackhammer. Don't ask me how I know.
>
> Wes N7WS
>
>
> On 4/5/2020 10:51 PM, Clay Autery wrote:
>> NO "water pipe" should ever be used as a service ground... I thought the code was changed to actually bar that practice entirely.
>>
>> ______________________
>> Clay Autery, KY5G
>> (318) 518-1389

Bob McGraw - K4TAX

Re: Hum on KPA1500

Electric garage door opener?   Most have internal SMPS units.

Drop the main breaker for the house and see if the noise goes away or
decreases on your car radio. If so, it is something in your house.
Now the hunt begins.   One step at a time, being one breaker at a time.
That will allow one to determine what circuit/room the issue is
originating.

Depending on the age of the house, the ground system may have
deteriorated and needs updating or replacement.   A qualified
knowledgeable electrician can assist in this regard.

Our house is 50 years old and I found the AC mains ground just below the
meter base had been eaten away by electrolysis. I had a new ground rod
installed and new cable ran to the meter base and then into the breaker
panel. Several issues were resolved with regard to lights getting
bright and dim for no obvious reasons.

73

Bob, K4TAX

On 4/6/2020 11:49 AM, David Christ wrote:

> That is exactly what appears to be happening. Heavy cable starts at service panel, proceeds into floor slab of garage which I assume is acting as Ufer ground. What appears to be the same cable emerges from the other side of the slab and connects to the water system. I think that it is fair to assume that that the cable emerging from the slab is also connected to the Ufer ground thus bonding the water system to the service system ground. This is one of those things that is difficult to unambiguously describe with words but so easily described with a very simple drawing.
>
> I have do doubts that the system was properly designed and safe. But we are getting off the question that I had about RFI. On 3/4/2020 K9YC discussed triplen harmonics in ground systems (I may not be stating it properly). The question is then “Could triplen currents in the power ground system as described be causing the interference I experience when entering my garage?” or is there another explanation for the RFI?
>
> I repeat the description
>
> The AM radio in the car works fine in the driveway, but as soon as one starts to enter the garage, reception is covered up by a loud growl of static. Radios in a room adjacent to the garage and over the cable in the basement below also have a problem while AM radios at the other end of the house are fine.
>
>
> David K0LUM
>
>> On Apr 6, 2020, at 8:39 AM, Wes <[hidden email]> wrote:
>>
>> I believe that is the case. However, one point on the water piping should be bonded to the service ground for safety reasons. Using the piping for current-carrying purposes is a really bad idea. Keywords: Copper pipe, dirt, concrete slab, jackhammer. Don't ask me how I know.
>>
>> Wes N7WS
>>
>>
>> On 4/5/2020 10:51 PM, Clay Autery wrote:
>>> NO "water pipe" should ever be used as a service ground... I thought the code was changed to actually bar that practice entirely.
>>>
>>> ______________________
>>> Clay Autery, KY5G
>>> (318) 518-1389
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Jim Brown-10

Re: Hum on KPA1500

In reply to this post by David Christ

On 4/6/2020 5:47 AM, David Christ wrote:
> Until I solve this one I will not be able to complete killing all the noise in the house.

This sentence suggests that you didn't study the link I posted.

73, Jim K9YC
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ANDY DURBIN

Hum on KPA1500

In reply to this post by Carl Yaffey-2

"The AM radio in the car works fine in the driveway, but as soon as one starts to enter the garage, reception is covered up by a loud growl of static. Radios in a room adjacent to the garage and over the cable in the basement below also have a problem while AM radios at the other end of the house are fine."

In what way, if at all, is this observation/question related to the report of KPA1500 hum?

With reference to the original report - what is origin of the hum? That is - what physical object is originating the sound waves that are characterized as hum. There was no mention of an AM radio in that original post.

Andy, k3wyc
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Jim Brown-10

Re: Hum on KPA1500

In reply to this post by David Christ

On 4/5/2020 9:06 PM, David Christ wrote:
> That I understand but if the ground from the entrance breaker panel to a water pipe from the street is 30 feet long, can it radiate interference to AM radios near it (both AC and bat

Any conductor carrying RF current WILL radiate it. That's antenna
action. The "hum" and "buzz" described in my earlier post are NOT RF,
they are baseband (60 Hz and harmonics).

The mechanism whereby a coax feedline is carrying RF current into our
shack producing hum is that the current couples into electronics
(usually by a Pin One Problem) and changes the bias state of some gain
stage.

73, Jim K9YC
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ANDY DURBIN

Re: Hum on KPA1500

In reply to this post by ANDY DURBIN

"The mechanism whereby a coax feedline is carrying RF current into our shack producing hum is that the current couples into electronics (usually by a Pin One Problem) and changes the bias state of some gain stage."

My understanding of the original post is that hum was heard in the shack and that the origin of that hum was believed to be the KPA1500. We still have not been told if the hum came from the PSU or the RF deck.

I can understand that RF current coupling could possibly influence the quality of the KPA1500 transmitted signal but how would that result in "hum" heard in the shack?

73,
Andy, k3wyc

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