The FCC (Federal Government) says this as Of Sept 1, 2021
§ 15.219 Operation in the band 510-1705 kHz. (a) The total input power to the final radio frequency stage (exclusive of filament or heater power) shall not exceed 100 milliwatts. (b) The total length of the transmission line, antenna and ground lead (if used) shall not exceed 3 meters. (c) All emissions below 510 kHz or above 1705 kHz shall be attenuated at least 20 dB below the level of the unmodulated carrier. Determination of compliance with the 20 dB attenuation specification may be based on measurements at the intentional radiator's antenna output terminal unless the intentional radiator uses a permanently attached antenna, in which case compliance shall be deomonstrated by measuring the radiated emissions.
This is on my station Facebook page, linked to Federal Law.
"...to the final radio frequency stage (exclusive of filament or heater power)"
Ok... that line never really hit me.. "exclusive of".. So if I'm reading it right it's actually saying:
The total input power to the final radio frequency stage which is contained within the filament or heater power section of the circuitry shall not exceed 100 milliwatts
This implies that the antenna certainly is considered as a part of the "radio frequency stage", which makes sense to me, and it is indeed the last stage of it,..
..HOWEVER, the antenna falls outside of the "filament or heater power sections" where the 100mw reading is to take place.
I never really noticed that before, and it really clears thing up.. but it would be even clearer if I understood what the filament or heater power was.
Because that specification had never really hit me before.. It's just not something you ever have to even worry about if your using a certified transmitter.
So what exactly is the filament or heater power section of a transmitter?
"...to the final radio frequency stage (exclusive of filament or heater power)"
Ok... that line never really hit me.. "exclusive of".. So if I'm reading it right it's actually saying:
The total input power to the final radio frequency stage which is contained within the filament or heater power section of the circuitry shall not exceed 100 milliwatts
This implies that the antenna certainly is considered as a part of the "radio frequency stage", which makes sense to me, and it is indeed the last stage of it,..
..HOWEVER, the antenna falls outside of the "filament or heater power sections" where the 100mw reading is to take place.
I never really noticed that before, and it really clears thing up.. but it would be even clearer if I understood what the filament or heater power was.
Because that specification had never really hit me before.. It's just not something you ever have to even worry about if your using a certified transmitter.
So what exactly is the filament or heater power section of a transmitter?
They're talking about the filament/heater in a vacuum tube. The rule is saying that the 100mW DC input power does not include the power that the filament draws. This, of course, does not apply in a solid state final.
It absolutely does not imply that the antenna is considered to be part of the final radio frequency stage.
Honestly Rich, if you're genuinely interested in this stuff, it would really pay off to read some books on RF engineering, or take some classes. That way, you can learn some of the theory, as well as the terminology. I genuinely don't want to be offensive, but listening to you talk in this thread, is like watching someone listen to a Frenchman talk in his native language, then claim that he means something completely different, because the only langauge you speak is German. Whenever engineers talk about transmitter finals, they are always referring to the final amplifier stage. Always. Believe me - I've built a lot of finals.
Reading your missives on this subject make me feel like I'm beating a dead horse. I feel like if you went to college and took a class on how to bias a transistor in a common emitter amplifier, you'd spend your time questioning the lecturer's use of the word "bias", or how appropriate and accurate it is to call one of the transistor connections the emitter, based on it's meaning in regular language usage, instead of actually learning how to bias a dang transistor!
I genuinely do not mean to cause offense, so I hope I haven't caused any.
They're talking about the filament/heater in a vacuum tube. The rule is saying that the 100mW DC input power does not include the power that the filament draws. This, of course, does not apply in a solid state final.
Oh! Excluding the power that the filament draws. Ok, that's totally different then what it thought it was saying
:It absolutely does not imply that the antenna is considered to be part of the final radio frequency stage.
I get that now, and no, you havent offended me in the least. I know that I know nothing but the most superficial generalities about such technical matters, so no it doesnt bother me when someone brings my ignorance to light.
I have no intentions of studying up radio theory and circuitry or anything, I'm too old to embark on that -- or maybe not, but I just dont expect to take the dive... However, I have been thinking it's about time I try building an AM transmitter kit.
I agree with the others here who suggest the power input rule means the last active (takes DC power to operate) stage.
So here's a question... is the 100mW input power apply to only the amplifier generating the RF carrier or also to the audio power driving the modulator after the carrier generation? This assumes this is the AM approach that directly modulates the final carrier signal.
I agree with the others here who suggest the power input rule means the last active (takes DC power to operate) stage.
So here's a question... is the 100mW input power apply to only the amplifier generating the RF carrier or also to the audio power driving the modulator after the carrier generation? This assumes this is the AM approach that directly modulates the final carrier signal.
Pretty sure it refers solely to the DC input power to the final (PA) stage. That's the convention for such things. With the Rangemaster, when adjusting the power, you adjust it to ~100mW DC input with no modulation i.e. an unmodulated carrier.
@jsh4 The rule states, or stated, 100mW DC into the final implying the it is it is measured with no audio. But has DC been removed? I remember it was there. If DC is not in the wording anymore then the 100mW applied to the final amp can be with audio(modulated) or not which could be a bit better for you as an unmodulated carrier is stronger than a modulated one. In that case it's desirable to do the measurement with audio. The Canadian wording last I looked had the term DC for AM and unmodulated carrier for FM. I should look again.
Oh oh! here's another can of worms I opened up!