Total posts : 45366
Back to the FM range question, I can’t say as I’ve done this, but someone else has and told me about it. With a “cheap” omni antenna (a V with an inverted V rotated 90 degrees, about 3db gain) up on a hill and a 10 watt capable transmitter running at somewhere between 1 and 2 watts (low power setting is 0-2 watts), the range was many miles (at least 5 miles). Antenna location is 50 feet off the ground, with a building that sits up on a hill.
The transmitter was connected through about 100 feet of RG-8, and the transmitter was brand new, and built from a reliable company. The company that built the tranmitter also built the antenna, and the antenna tower, and ran the coax cable. Audio was fed through an Inovonics stereo generator into the tranmitter. I tested this same rig at minimum power on the indicator, and it gave much too much range compared to a part 15 FM rig. That range was our complete campus, and the power indicated was less than .25 watts on the meter. The low end of the power meter was a little tough to determine. Our campus is about a quarter mile in diameter, and the radio used for that last bit of testing was ultra cheap with poor reception (it cost a whole $5 new).
So one watt with a raised 0db gain omni antenna should give a pretty good range depending on location. I think running half a watt into what we have would be a good start, and give us a nice strong FM stereo signal over the entire campus, and some of the surrounding housing where many of our students live. That would be about .75 watt effective power, and agian, it would be a start.
I’d love to do more testing, but after I found that the minimum power output was too much, I removed the transmitter and put it in storage just to prevent it from being used again.