I’m still pretty new to radio stuff and still learning. I have my technician license and have made a handful of contacts. For Christmas I got the RTL-SDR. It has a warning saying “DO NOT use near strong transmitters. Max input: +10 dBm.” I am having difficulty understanding exactly what that means and whether I can use my handheld radios near it. These are cheap ~5W radios.

I’m curious about the practical and theoretical both, here. So a simple yes-or-no would be helpful, but I’d also like to know the math.

• Right now, I have a vertical half wave dipole (each leg is 48.8 cm, which I believe makes this a half wave dipole antenna for 146 MHz?) attached to my RTL-SDR. I’ve been trying to understand gain, but it seems tricky to find and understand the charts. This antenna came with the RTL-SDR, but it’s telescoping and that’s the length I have it at.
• My radio is 5W and uses a knockoff NA-771 type antenna.

I don’t have any other sort of tool to measure the output of my handheld radio. I am curious how close I can be to the RTL-SDR antenna when transmitting. I am also curious if I can transmit near the RTL-SDR when there is no antenna attached (I assume I can be a lot closer, but I still don’t know how close).

Mostly, I don’t want to break a new toy lol.