[RFI] FCC Limits on Harmful Interference: Clarification

Kim Elmore cw_de_n5op at sbcglobal.net
Sat Dec 28 21:38:16 EST 2019


 From what I've understood form Ed Hare, "harmful interference" is 
defined on a case-bay-case basis. I don't think we want a hard and fast 
limit, to be honest. What works in one case may be a disaster in another.

Kim N5OP

On 12/28/2019 7:49 PM, Tony wrote:
> All:
>
> I made the mistake of hitting send without editing so I apologize for 
> my previous post on radiated emission limits. As Ed Hare mentioned 
> numerous times, there are no FCC limits on radiated emissions below 30 
> MHz.
>
> What I meant to say was this:
>
> Ed mentioned that the FCC had taken action based on harmful 
> interference and I assumed it was based solely on the definition of 
> interference and not how it was generated i.e, radiated or conducted. 
> Hence, I asked how the FCC measures harmful interference.
>
> This seems logical because the term harmful interference would be 
> meaningless if the FCC only deems it as such if it's conducted and not 
> radiated -- it's either harmful or it's not.
>
> Or am I missing something?
>
> Tony -K2MO
>
>
>> Actually, the?? FCC really hasn't given up on?? HF.?? What I have said 
>> is that there are no radiated emissions limits for unintentional 
>> emitters below 30 MHz. (There are conducted limits onto the AC 
>> mains.)?? But the FCC has sent out many dozens of?? advisory letters to 
>> operators of various devices on the basis of harmful interference.?? 
>> Now, they will set a higher threshold for?? harmful interference than 
>> we like, but the?? can and do take some (limited) action.?? ARRL has 
>> worked hard to keep this alive in the FCC, and?? so far, it has held.
>>
>> The solar?? panels?? are unique. Their conducted emissions limits apply 
>> ONLY the ac mains, not other wires, so many of these systems that can 
>> and do cause interference do actually meet the laws about radiated 
>> and conducted limits. Solar Edge may be a bit slow, but they?? are 
>> responding and?? ARRL maintains regular contact with them. We have a?? 
>> few unresolved cases and we are planning a field trip?? to go take a?? 
>> look at?? them in person, hopefully with Solar Edge?? and Telsa also 
>> present.
>>
>> Ed
>
>
>
>
>
> , just CONDUCTED emissions, and that is only on the side that attaches 
> to the power lines.
>> So say the panels, optimizers etc are radiating like mad, but the 
>> side of the inverter that hooks to the mains is clean. They meet part 
>> 15.
>>
>> Hence the problem
>>
>> -- 
>> 73 de KG2V
>> Charlie
>>
>>> On Dec 28, 2019, at 2:56 PM, Tony <dxdx at optonline.net> wrote:
>>>
>>> ???On 12/22/2019 6:19 PM, Hare, Ed W1RFI wrote:
>>>> the FCC has sent out many dozens of advisory letters to operators 
>>>> of various devices on the basis of harmful interference.
>>> Does anyone know what the FCC limits are on harmful interference 
>>> caused by radiated emissions with regard to HF and the amateur radio 
>>> service? Is the noise measured at the receiving station or is it?? 
>>> measured at some specified distance from the offending device?
>>>
>>> It would be interesting to know if the same FCC standards apply to 
>>> commercial and aviation services.
>>>
>>> Tony -K2MO
>>>
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>
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-- 

Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP 
SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)

/"In theory there is no difference between theory and practice. But, in 
practice, there is." //??? Attributed to many people; it???s so true that it 
doesn???t matter who said it./



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