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Carl Blare's blog

Low Power Hour No. 72

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Episode 72 begins with Low Power in the News including several stories straight from the Forums and Blogs of Part15.us, as well as news of a hacked EAS System at KRTV, Great Falls, Montana; a report on 50kW KAAY, Little Rock, Arkansas, 1090 AM; a quick stop at the website for End 80 Radio, Tybee Island, Georgia; and a new "end of the world prophesy" to replace the expired Mayan and Rev. Camping predictions.

Filament

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The expression "exclusive of filament or heater power" as stated in 15.219 has never become clear to my understanding. Obviously it refers to electron tubes, which contain filaments. "Heater" is another word for filament, owing to their contribution to heat within the tube. But in determining the input to a final electron tube stage the power drawn by the filament is clearly separate from input or output power from that tube, so there seems no reason to mention filament power at all. Why are filaments mentioned in the rule?

Detailing the Sketchy Rules

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In this blogger's opinion the Part 15 Rules are sketchy.

They lay out a model scenario; a general situation; a typical setup.

But the Part 15 Rules do not attempt to anticipate the infinite possible situations that might arise, and therefore must be applied creatively.

Let's start with the known, and work our way outward from there.

At your house the Rules allow an AM transmitter with 3-meter antenna, 100mW to the input of the final RF stage. A well worn fact. Such a transmitter, if well installed, might reach 1,000-feet or better.

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