Well, the "regulatory stuff" is important more than ever in the 21st Century, because the available spectrum is becoming extremely crowded.
Back in the day (while still a teenager), I built a low-power AM broadcast band transmitter and put it "on the air" in my neighborhood, at first re-broadcasting the audio of an existing radio station so I could do a "walk about" to find out how much range the transmitter had. Not much: I couldn't hear it more than a few hundred feet away using a portable transistor radio. I didn't know at that time that the NSA (National Security Agency) had very sensitive receivers that could easily record my illegal transmissions from miles away. Nevertheless, I sweated bullets every time I fired that puppy up, fully expecting a visit from the FCC (Federal Communications Commission) enforcement branch at any time. This fear was enough to lead me to abandon and disassemble the transmitter after only a few weeks of experimentation with a friend who lived a few houses away on the same street.
A few years later, while serving in the Air Force, I obtained a Novice Amateur Radio License (call sign KN8UTJ), built a legal transmitter, and got on the air on the Novice portion of the 80M band, banging away on a telegraph key to improve my Morse Code listening skills... transmitting about fifty watts into a tuned dipole antenna mounted on the roof of my barracks. Never built or operated another illegal transmitter after graduating from high school.
The Feeltech Chinese DDS signal generator does not have a modulation input.
