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Post by Deleted on May 10, 2016 0:05:50 GMT
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Post by Admin on May 10, 2016 12:27:22 GMT
Welcome aboard!
The expected range of a legal Part 15 FM broadcaster is around 200 to 300 feet. "Line of site" has a lot to do with it especially at the allowed signal strength so placing the transmitter/antenna up high will help.
Using your external antenna could be a problem for a few reasons. First, if it's a typical folded dipole antenna, there is probably a balun or transformer to match the antenna impedance to the coax impedance. Designed for receiving antennas, I'm not sure how well it will work for transmitting as it may be very lossy. Second, if it is a directional antenna it will actually reduce your signal in some directions depending on how the antenna is built. A simple folded dipole would have a figure-8 pattern in the horizontal plane. A multi-element yagi or log periodic antenna would concentrate the signal mostly in one direction. There are non-directional folded dipoles in the shape of a circle. Third, the combination of RG-6 or RG-59 coax and a receiving antenna as a transmit antenna system will probably result in a lot of power loss but using a .5 to 7 watt transmitter would probably still result in more power than permitted.
Next, changing the antenna of a transmitter which is FCC Certified for Part 15 will invalidate the certification. The safest thing to do to avoid that would be to place the unmodified transmitter/antenna combination in a weather-proof box and mount it outside, up high. Power and audio cables would run back to your operating point.
FM has the obvious advantage of good fidelity and stereo but the Part 15 restrictions severely limit the range of the transmitter. For that reason many decide to setup an AM station which can in some cases legally obtain a mile or two of usable range to a car radio.
Don't get discouraged yet! Try your external antenna or better yet mount the unmodified transmitter/antenna outside and see how it does. If it goes a mile or more chances are you'd better reduce that. It may be that no one would notice but if someone complains you may be visited by the FCC.
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Deleted
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Post by Deleted on Jun 30, 2016 14:24:32 GMT
Where Did fmradio Go?
Interfere with nearby stations on the same frequency?
If there are nearby stations on "the same frequency" you can't use that frequency. That's how you avoid interfering with stations on the same frequency.
1 to 7 Watts?
Perhaps you should actually read the Part 15 Rules before saying you want to comply with them. By saying "1 to 7 Watts" you reveal that you have no idea what the rules say. That much power is not permissible on FM in The Homeland (formerly the USA).
Anyway, how's it going with your station?
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Post by thelegacy on Jul 1, 2016 22:54:54 GMT
7 Watts per Youtube can go 10-15 miles usable to a Digital Car Radio. There was a test of a 7 Watt transmitter and there was spots (Small pockets) where the signal was traveling over 20 miles and almost perfect Stereo separation. Now keep in mind this was given for educational purposes only just to give an example of range. The transmitter was on the second floor and using the telescopic antenna.
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