HMB uses 5 rangemaster linked together within about 25 feet of each other - give or take. in an X pattern..
Again.. Perhaps I'm mistaken, but I understand that such an install is illegal because it would in effect becomes at least a single 15 meter antenna system...
Case in point in this 2011 NOUO: ...Specifically, section 15.219(b) of the Rules states "the total length of the transmission line, antenna, and ground lead (if used) shall not exceed approximately 3 meters." During the inspection on May 15, 2011, the agent observed the station had five antennas mounted on the roof, each with a vertical whip approximately 3 meters long, and the ground leads totaled over 15 meters in length. This antenna installation violated section 15.219(b) of the Rules. http://transition.fcc.gov/eb/FieldNotices/2003/DOC-308327A1.html
5 x 3 meters = one 15 meter antenna..
No??
Yes, 5 antennas connected one transmitter and each grounded would certainly be illegal. However the hamilton system uses five seperate transmitters with five seperate antennas and grounds. This makes it legal if each installation is OK.
Tim in Bovey
One 15 meter antenna if all antennas were connected to the same transmitter, perhaps. But, if 5 transmitters each had it's own separate antenna I don't see how that would be considered as one system antenna exceeding the 3 meter rule.
Even so, it would seem if one transmitter with 5 antennas each 3 meters long in close proximity to each other (less than a few inches apart) and fed from a common point, that should be considered as one antenna 3 meters long. For instance, 5 - 3 meter long insulated wires such as a multi-conductor cable with common feed point and open at the other end would still be one-3 meter antenna.
I had an idea for a wide bandwidth antenna whereby 3 elements of different lengths (each within the 3 meter rule) fed from a common point, one being cut to the center frequency and the other two cut slightly above and below the center frequency to yield a bandwidth of 20 or 30 kHz. This would be similar to the ham radio "fan" antenna or perhaps a cousin of the "log periodic" antenna. That would allow the sidebands (where the money is) to radiate efficiently.
But then I wonder if the power divides among them, is the total field the sum of the individuals or of the single greatest field.
Below is an analysis of an array of five 3-m monopoles close together using five separate transmitters, all phase-locked on the same frequency.
Each system by itself could be compliant with FCC §15.219, but in this configuration this composite system is radiating more power than can be provided by a single system meeting 15.219.
A larger graphic is possible by right clicking on the one below, and selecting "View Image" -- at least when using Firefox.
no. the ground leads were the killer in that case.
the fcc is clear about multi-transmitter installations. you are allowed multiple transmitters; but they have to adhere to the rules. 3meters per transmitter including ground lead. that NUOU was due to exceptionally long ground leads.
Unfortunately the link is unavailable ( See this FCC Publication addressing Multiple Part 15 Transmitters )
As always, however, the "legality" of *any* part 15 installation is up to the inspector. You could follow every rule to the letter (or number, in our case), and still be removed from the air.
If this becomes a thread regarding the legality of multi-transmitter installs, etc - can we move it to a new discussion so we do not confound and confuse the new guy - who seems to have a GREAT forward thinking attitude, and it would be awesome to keep him that way 🙂
i was too late.. here we go.. again.. omg.
i think i am having an anurism.
are you happy now? you killed me with yet another "this is wrong because my math says so" post.
Now my cat is homeless.
Below is a clip from a thread at http://www.part15.us/forum/part15-forums/general-discussion/gray-area-uncovered
That thread is an interesting read. AFAIK this topic has never been resolved.
That's an interesting interpretation of the rules.
There's nothing that says that you can't have 5 Part 15 transmitters, each with their own 3 meter antenna, at least in the U.S. If each of them were on a different frqeuency, and transmitting different programming, then it would be OK, presumably, but if they're on the same frequency, they're not? A very grey area, to say the least.
You can't have multiple transmitters transmitting from the same source in Canada, by the way - it's explicitly prohibited by the CRTC.
It seems to me that you're taking an awful chance if you put your livelihood into multiple transmitters in a single site install, and then get it shot down by the FCC.
Here's what I'd do.
First, I wouldn't quit my day job just yet. You should try things out first, particularly if you've never done Part 15 broadcasting before, to make sure that you're going to get what you think you're going to get out of it.
Why not set up 2 transmitters, not on the same site, perhaps 1/2 mile away from each other? That should keep you away from any grey areas in the FCC rules with multiple transmitters. You'll have to decide whether to have them on different frequencies (in which case you don't have to worry about synching them) or on the same frequency (then you'll have to synch them - I'd recommend some sort of wireless link that doesn't randomly introduce delays) and then experiment. You'll be able to see the various ranges you can achieve to car radios and home radios. You'll be able to see if you can synch them if you go that way and what the issues are (i.e., do you have to resynch everything if the power goes down). Or if you go with different frequencies, you'll be able to see if that is a deal killer in your specific application.
I'd also really recommend looking at setting up an Internet stream, which could be used to listen in to your station on the fringe areas. Again, you can experiment - it isn't all that hard to do, and can increase your listenership substantially (which increases ad sales).
You'll make a (relatively) minimal investment overall and get much more 'hard' information than just theorizing here. If it doesn't work, then you won't have lost everything (you can always sell the equipment and get back some of your money).
Then, if you decide to go for it, you can use the results to determine exactly how many transmitters you require, and move forward.
One thing that I've learned about Part 15 broadcasting over the years - you actually have to do it. You can't change the laws of physics but we're dealing with such minimal power levels, and restrictive rules, that what might generally work in RF may not work here (factors that don't do much when you're dealing with full size antenna systems and thousands of watts can have major effects in Part 15).
You can't change the laws of physics but we're dealing with such minimal power levels, and restrictive rules, that what might generally work in RF may not work here (factors that don't do much when you're dealing with full size antenna systems and thousands of watts can have major effects in Part 15).
Just to note that there are no factors in the equations dealing with the performance of transmit systems that, other things equal, relate their performance differences to anything but applied power.
Hello everyone. I'm still out working in the oil field. My rig finished drilling it's well and has been moving so I've been without internet for a couple days.
Ok, so here's what I've decided. I've got a perfectly good job right now. Sure, I don't enjoy it, but it pays above 100K/year, I'd be crazy to quit it. Because I make a great salary I can afford the equipment needed to start a part 15 station. I will remodel a building behind my house into a studio, a real studio. I will get 1 transmitter, put the antenna up on a 30-50ft tower, ground the tower pole really good and try and catch the entire town.
I will broadcast a live show for the two weeks I am home. The two weeks I am away I will run the station automated. I'm looking at ZaraStudio possibly as my software unless you guys have some better ideas. My live shows will be just that, live, as if I do it for a living. They will be professionally produced, and have professional imaging. The automated shows will be almost live. I can pre-record most of the stuff like birthdays, school lunch menus, psa's, this day in history, etc and run them as commercials during the automated shows. That way people get 2 weeks live, and the other two weeks about the only thing they'll be missing is current time, temperature and weather. Other than that they will still get basically the same show.
I will try and get some advertisers. If I don't, no big deal, I still have my job that supports me. If I do get advertisers, great, maybe a little extra income during the month. If I get a ton of advertisers, even better, maybe eventually I'll quit my job and do the show full time. But for now I'll treat it like a hobby, build the shows, the different little programs in the shows, and just have fun with it.
That's probably the more sensible thing to do anyways, rather than quitting my job and running off to do this crazy idea. A little at a time, and maybe one day I can quit my job, and if not, that's ok too. You guys have had some great ideas, and I'm glad I found this site. Thanks a lot for all your help. I'm sure as I go on, I'll have more questions. And hopefully as I learn more, I'll be able to pay it forward to someone else.
Just a word of warning. If you elevate your installation, grounding the transmitter to that tower, the FCC could consider the tower part of the ground lead, and find you in violation of the 3 meter antenna+ground lead+feedline rule. That's why I recommended a ground-level install, with a short ground lead to a very good ground (i.e., multiple ground rods pounded into the soil, plus radials). The FCC has let such installations pass in the past, but more recently they haven't accepted them. If you feel comfortable with the risk, go for it, but if you want to make every effort to remain legal, I'd stick with the ground-level installation.
Zara will do automated Time/Temperature/Humidity announcements. You'll have to add prerecorded audio clips for all.
Weather Watcher will retrieve the current weather data which Zara will use to play the correct temperature and humidity audio clips.
You can keep your clock current using one of the many web based clock synchronizers.
If your local NOAA WX station offers mp3 audio of the current weather you can even automate playing the current weather files.
You can find a Zara compatible Weather Watcher app on my WEBSITE.
If you have questions regarding setting these up let us know.
Warning is negative. Carl should have taught that. Caution is friendy. Carl should have taught that.
My earthly teaching on the subject suggests saying:
Warning! Caution is advised!
In this way negative converts to positive.
WDCX is one of my believers. Unless I have that wrong.
By this point, if I knew what the thread topic is, I could speak to that.