[Elecraft] Hum on KPA1500

[David Christ]

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 <KY5G at montac.com> 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 <jim at audiosystemsgroup.com> 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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