[TowerTalk] Station Noise

jimlux jimlux at earthlink.net
Thu Oct 22 19:05:22 PDT 2009


Al Williams wrote:
> a minor technicality ( I think)
> 
> the rules are not if they create interference but rather if the field 
> strength at some freq bands and distances exceed the stated limit 
> ???????????
> 
> If my memory is correct, the stated limit is really pretty high in the hf 
> region ???????????
> when compared to the sensitiviy of modern transceivers.
> 


For Part 15 (which others have pointed out may not apply to the fan 
motor speed controller in question), it's both.  There's a radiated and 
conducted field strength limit and a "shall not interfere, and shall 
accept interference" rule.

BTW, I think an inverter type motor speed controller would need to meet 
Part 15 rules as an unintentional radiator. If any part of the digital 
logic has a clock that exceeds 9 kHz, it generally has to meet the 
rules. There are exceptions for things powered solely by batteries (but 
you can't have it "charge and operate" at the same time.. hence the 
things you see that either charge OR operate, but not both).  But I 
don't have my Part 15 handbook here..


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