Total posts : 45366
I want to sound the alarm on this transmitter and give some real world comparisons to us all.
My FM station is using a Ramsey FM-30B running at around 3 milliwatts output into an end-fed coaxial-rat-tail dipole antenna. Even in the car, I can here the station about 200 feet in all directions. I WAS running approx. 10 milliwatts and covering way to much real estate. I can’t imagine getting away with 100 milliwatts or more on the FM band.
For comparison, licensed FM stations consider their broadcast area to include the 1 millivolt or 60 dbu contour, otherwise known as the inference free contour. For Class A FM stations (3KW at less than 100 meters HAAT) this would extend out to about 15+ miles or so; LPFM 100 watt stations out to about 3-1/2 miles.
When you reduce a 1 millivolt/m signal by -6 db you arrive at 250 microvolts per/meter or the legal Part 15 limit at approximately ten feet from the antenna for an FM transmitter. That’s right, at 10 feet Part 15 gets 1/4 the usable signal of a license FM in its interference free signal contour miles from the transmitter.
This unit is a citation looking for the opportunity to happen. If you live in Canada, or outside the U.S., this unit might be usable. In the good ol’ U.S.. I wouldn’t.
Remember that an LPFM filing window is coming up soon. If you are cited for an unlicensed violation the possibility of getting a construction evaporates entirely. Read the LPFM rules. Is $60 worth your future as a broadcaster? I think not.