[RFI] Comments on RFI from Ductless Air Conditioning Units?

[Dale]

Cortland,

Thank you for the update on exempted items per Part 15.  However, I note the wording "not cause harmful interference" still applies. That's great, but as has been noted many times in this forum, the interference happens all too often.  As we all know, when the appliance is owned by anyone other than the affected op, getting rid of the problem is not easy (and often not practical).  

Sadly, one of the most important truths about RFI suppresion and control is: contain or eliminate the interference at its source (part of the axiom to reduce power level of the source).  The other truths are increase of separation distance between source and victim (often not possible) and improved rejection of the source by the victim (usually not possible or practical if the victim is an actual antenna, might be possible if the victim is a cable acting as an antenna).

73, Dale
WA9ENA     


-----Original Message-----
>From: Cortland Richmond <ka5s at earthlink.net>
>Sent: May 13, 2013 8:24 AM
>To: rfi at contesting.com
>Subject: Re: [RFI] Comments on RFI from Ductless Air Conditioning Units?
>
>it is worth remembering that most appliances are exempted from Part B 
>(or A) at 15.103, only having to comply with not causing harmful 
>interference. FCC Knowledge data base I see that new guidance last year 
>removed exemption Verification (Section 2.902) for: External Thermostats 
>connected via wire and not contained within the appliance, Exercise 
>Equipment, Hair Dryers, Heat Guns, Hair straighteners, Electric 
>Blankets, Paper Shredders, Bed Warmers, and Portable Personal Fan Heaters.
>
>
>See Publication Number 772105 
><https://apps.fcc.gov/oetcf/kdb/forms/FTSSearchResultPage.cfm?switch=P&id=33062> 
>(3/29/2012) (new).
>
>excerpt: /An exempt appliance is only exempt from equipment 
>authorization procedures for the functions associated with the digital 
>device circuitry.*The appliance remains subject to the requirements in 
>Section 15.5 requiring the device not cause harmful interference, and 
>Section 15.29 regarding inspection by the Commission.* It is strongly 
>recommended that manufacturers or importers make every effort to meet 
>the specific technical standards, follow appropriate FCC equipment 
>authorization procedures, and comply with quality practices to ensure 
>all units sold and marketed are, and will remain, compliant. /
>(emphasis added)
>
>Cortland
>KA5S
>
>On 5/12/2013 2251, Dale wrote:
>> David,
>>
>> Be certain to specify FCC Part 15 Class B limits.  Those are the limits applicable to home and office environments.
>>
>> After that, it will then be up to you to determine if Part 15, Class B limits are, in fact, adequate for your application.  Keep in mind that if your antennas are fairly close to the shack or house (less than 50 feet away), you could still have problems with RFI, especially in the HF range.  You probably won't know until you try it.
>>
>> 73, Dale
>> WA9ENA
>>
>>
>
>
>
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