Total posts : 45366
The FCC doesn’t care whether you use a certified on non-certified transmitter. They only care about your operation if there is a complaint filed. Then they will check to see if your FM operation complies with section 15.239:
Section 15.239 Operation in the band 88 – 108 MHz.
(b) The field strength of any emissions within the permitted 200 kHz band shall not exceed 250 microvolts/meter at 3 meters.
This field strength limit typically results in a range of 200 ft. Your only responsibility as a user of a certified or uncertified transmitter is to ensure it doesn’t exeed the field strength limit.
OK, so you buy any certified or uncertified transmitter and turn it on. Now use a really good portable radio or a car radio and go to 200 ft and beyond. If the signal is listenable beyond 200 ft. go, back and reduce the power (if that is an option) or shorten the antenna. Do this until you comply. Logic and common sense say you won’t get a complaint.
It seems that every time anyone posts a link to an uncertified FM transmitter on any forum, there is a barrage of posts warning about “possible” legality issues. On the other hand, there are many posts asking how to increase the range of certified FM transmitters. Sanity check here. What is expected?
If you are a part 15 FM broadcaster, you need to decide if you want to stay STRICTLY legal, or push the limits a bit.