[Elecraft] Hum on KPA1500

[Bob McGraw K4TAX]

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 <wes_n7ws at triconet.org> 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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