I was pleasantly surprised by a mail from one of my readers who is a PhD Electrical Engineering student. He put his access to a Tektronix RSA 5103A to good use and did some additional measurements on his brand new UV-5R. He writes:
I thought you might find these figures interesting. I’m a PhD Electrical Engineering student and have access to a Tektronix RSA 5103A in our research lab. I honestly don’t have much of an EM/RF background (my work is mostly DSP) so this tool is far more capable than what I know what to do with it. But I’ve attached a few figures. Two measuring occupied bandwidth for wide and narrow settings on the radio.
On the left of the figures you’ll see two bandwidths. OBW (Occupied bandwidth) is the bandwidth occupied by 99.9% of the received power. x dB BW shows the -60 dB bandwidth, which is also shown in the figure by the blue lines. M1 is an approximate noise floor. I just blew into the wired mic to make noise while transmitting. The third shows some harmonics and their power, which match closely with what you measured.
I also wanted to say that, like you say on your blog, if I wasn’t careful, I could easily overdrive the spectrum analyzer input and get crazy stuff on the screen. When I just stepped back a little to attenuate the received signal, it cleaned up nicely.