On another thread, about top hats for Rangemaster transmitters, PhilB wrote:
On another thread, about top hats for Rangemaster transmitters, PhilB wrote:
There are only two FCC rules that apply to Part 15 transmitter users: 15.209 and 15.219. If you comply with one or the other, you are legal.
Well, so during the day we use 15.219.
Then, after sundown, we use 15.209.
See what I’m saying?
I’ll Bite
Why would you want to restrict your field strength between sunset and sunrise.
As long as you meet the input power limit and antenna system limit of Part 15.219 you are in compliance day or night.
And (although I now hate to use the phrase) prevailing opinion is that a well designed Part 15.219 system will exceed the field strength limits of Part 15.209 and therefore provide better range while still being compliant.
The Idea
The idea I have is that because at night the signal becomes so ineffectual because of the rise of skywave background noise, perhaps one would benefit from seeking the maximum allowed radiation level as opposed to the usually acceptable daytime level easily reached by simply employing the 3-meter/100mW guideline. Would that not be true?
Why ever seek less than the maxium allowable?
so during the day we use 15.219.
Then, after sundown, we use 15.209.
See what I’m saying?
The idea I have is that because at night the signal becomes so ineffectual because of the rise of skywave background noise, perhaps one would benefit from seeking the maximum allowed radiation level as opposed to the usually acceptable daytime level easily reached by simply employing the 3-meter/100mW guideline. Would that not be true?
What am I missing? I echo Mrams reply:
Why would you want to restrict your legal field strength .. under any circumstances at all?
Maybe My Point Isn’t Clear
I believe I have an interesting point, but if so, it must not be as obvious as I think it is.
It will be interesting to see whether anyone eventually has the same thought I think I have.
It is a point worthy of consideration
I believe I have an interesting point
It is an interesting point. I suppose the point then, or rather question would be, exactly how do all the various setups achieve this switch between 209 and 219 when the majority have taken great pains to maximize the 219 configurations?
Not everyone is sporting a rig that is easily adjusted for more horsepower at the output, not to mention the re-tuning that may be required on the elaborate antenna systems already peaked and tweaked for their current configurations.
But a good base idea..that is if everyone had the same exact setup and same variables at each location…which is not only impossible, but unrealistic.
Best way to accomplish your idea would be to have two setups, one peaked for 219, the other 209, then simply turn one off, the other on at the appropriate time and avoid all the back and forth re-tuning and other issues involved with just one setup.
One more thing.. I would not use the word “rule” here with this idea. There is no rule about day time/night time operation in Part 15. The use of the word rule in association with your idea is misleading. How about “Day Time/Night Time option
RFB
You are correct About
RFBurns is correct that if my idea has any validity it would be most practical to have two systems, although some clever engineering might be able to accomplish it with one system.
The word rule in my use refers to 15.209 and 15.219, which are alternate rules.
AM is most effective during full daytime, when we assume that using 15.219 as our “rule,” we may possibly surpass the limitation set by 15.209. But after sundown the signal becomes far less effective and we are assuming that it no longer achieves 24,000 microvolts/F at 30-meters distance, in which case 15.219 would fall below the threshhold allowed under 15.209.
By turning at night to 15.209 we could either raise power and/or extend the antenna to achieve 24,000uV/F at 30-meters distance.
Whether this alternation of the two rules would work as I imagine has never been tested or reported, so far as I know.
Tricky Risky
By turning at night to 15.209 we could either raise power and/or extend the antenna to achieve 24,000uV/F at 30-meters distance.
Although 209 does not specify antenna length, would it be that easy to convince an inspecting field agent that going beyond 3 meters is ok since I now declare operation under 209?
I don’t think it would be that smooth going honestly.
Setting aside rules and length limits and so forth, the idea is still viable and worthy of at least experimenting with. Again we run into the antenna build issue. How far should that extending of the antenna go to achieve the 209 spec, or in the case of the power, how much bumping up should one go with that?
Yes it would be possible to engineer a “tricky sticky” scheme to accomplish a swap between 209 and 219 for one setup. The easiest way would simply be to re-adjust TX power to the point of reaching 24,000uV/F@30 regardless if anything is done with the antenna or its peaked tuned resonance. Basically just shove a little more juice to the stick should to the trick.
Or go overkill and incorporate re-tuning mechanism on the variable cap working off a sensing circuit which would also have dual settings to peak the 219 level and then the 209 level when the TX power is bumped up.
Or build a telescoping stick with some sort of extending mechanism and extend its length, in turn the re-tuning mechanism tweaks the tuning while the sensing circuit (pre calibrated) controls the re-tuning process AND the stick raising mechanism to reach the 209 point.
Can be done….question is….is it really worth all that to the end. One thing for sure, your gonna need a much bigger weather proof box for all this stuff!
Interesting though. My current 3 meter setup, which serves as a 3rd backup system to the CC, has a sensing circuit controlling a servo which drives the variable cap to peak the antenna automatically under the varying conditions from day to night to day, when it rains or snows or is hot and sunny dry. Manual control is accomplished by flipping a switch on the control box inside and peaking with a meter looking at the sensor sample. It was not a simple task getting it all to work properly like it sounds.
Anything that comes close to the thing makes the tuning arrangement go crazy, even when the next door neighbor’s dog hops the fence to run around in my yard, or the wind makes the antenna sway a little, you can watch the peak meter swing and see the tuning indicator led’s which indicate which direction the variable cap is going, minimum capacitance or maximum capacitance…..and sometimes it will hit either one of the physical extremes of that variable cap.
One problem we have out here are tree squirrels. They love climbing things. The box outside is big enough on the top for a tree squirrel to sit and enjoy the view, while the tuning unit attempts to compensate!
RFB
I can’t let this go by
But after sundown the signal becomes far less effective and we are assuming that it no longer achieves 24,000 microvolts/F at 30-meters distance, in which case 15.219 would fall below the threshhold allowed under 15.209.
By turning at night to 15.209 we could either raise power and/or extend the antenna to achieve 24,000uV/F at 30-meters distance.
Part 15 AM transmitters don’t experience less signal strength at night. Skywave skip conditions cause distant stations to come in with very much higher signal strength, swamping out our puny signal. The only way to combat the night time problem would be to INCREASE you transmitter’s signal strength to help “fight back”. If you are already running under 15.219 rules, that is not an option.
Modern AM radios have extremely effective AVC (automatic volume control), which completely levels all stations to the same volume regardless of the received signal strength. This makes it impossible to make a valid judgment by ear as to what’s really going on. With good AVC, It’s impossible to distinguish between a distant station getting stronger or your station getting weaker. Trust me, there is no physics that will make your transmitter have a lower field strength at night.
Older communication receivers typically had an AVC on/off switch and and RF gain control. If you have one, play around with it for a while and you will get the real picture. Turn the AVC off. Set the RF gain for a comfortable level for your transmitter during the day. Keep the settings and wait for a strong night time skip station. You will see that your station still has the same volume level and the skip station is coming in much louder.
Reality Has No Imagination
Or, imagination has no reality.
The immovable physics put forth by PhilB dispells what would have been a brilliant insight, had it been.
That was my last and final idea. Ionosphere of the brain.
Reality
“I reject your reality and substitute my own.” – Adam Savage “Myth Busters”
Carl, even though physics may establish “truth” as we know it, the perception that some folks harbor is their reality. The “new truth” has legs in this digital world where leaders of abstract thought and expression develop tribes of people willing to accept a new reality. And for linear thinkers and actors, it is simply maddening; insanity. To argue linearity with the “non-linear” population is pure folly.
I applaud the linear thinkers attempts at sanity. However, the odds are overwhelming. The “ionosphere of the brain” is, in it’s nature, the same as the earth’s atmosphere, constantly changing; morphing into a new thing by outside forces of the galaxy and the universe. It takes great perception and sensitivity to understand the changes and what they mean, even to know the ultimate affect of the changes. Most of these changes are not short term, but instead, imperceptibly changing the neural pathways in our brains.
So through imagination, we do change our own realities. -Just food for thought. I hungry. ;P
Going to Quote That
Marshall, as soon as I can get on the air, I’m going to quote what you said as a final proof.
I just hope nobody asks, “What does it prove?”
Looks familiar!
I now think that kk7cw and KENC are the same person.
“What does it prove?”
Answer: NOTHING. So begins the circular argument supported by circular logic. Wake me when it’s over.
Nothing is Not Nothing
Marshall, your philosophy runs deep. I have my copy of Jean Paul Satre’s “Being and Nothingness,” and by proving nothing, you haven proven half of his argument.
Now all you need to do for your “full circle” is to prove, no… not something….
You must prove “being.”
Something is evidently not the opposite of nothing.
Being
To prove being: who are you talking with? If not me (being), then who? So, isn’t that something? But, in the final analysis, it is all nothing, or, is it?
Note: The depth of thought here is only exceeded by the lack of timidity to look and sound stupid. Carl, your underwear is showing, maybe. Or, is that stuffing coming out? Oh well, maybe it’s nothing.
I love the stuff that comes
I love the stuff that comes out of this technical forum..
Taking Umbrage
My underwear isn’t stupid.
“My underwear isn’t stupid.”
Wow, educated underwear. Next thing you know, you’ll be in comic books. And then, we can all MARVEL at your underwear.
Not On Radio
A radio personality has no chance in comic books, because no one can see a radio announcer, which would leave the panels blank on the page.
The world has experienced comic radio when Bob and Ray did cartoons on radio by portraying an entire cast of fictitious characters with sound effects in a wonderful theater of the absurd.
Bob and Ray programs can be found on archive.org and are free to use under Community Audio