> A old times radio receiver, it cannot be detected? Or can it Old times radio receivers are low power transmitters. Their local oscillators leak out of the a

> A old times radio receiver, it cannot be detected? Or can it Old times radio receivers are low power transmitters. Their local oscillators leak out of the antenna enthusiastically. The physics hasn't changed. There is far less leakage in modern receivers, but our detectors are way more sensitive as well. And if you're a nation-state and free to fly drones over rooftops looking.... yeah, don't believe anyone that claims they can operate anything involving electromagnetic energy without risk of detection.