ElectronicsQuestions on Nostr: Should be possible, if I remember correctly, superheterodyne receivers, which is ...

Should be possible, if I remember correctly, superheterodyne receivers, which is pretty much every receiver, do emit some RF energy. I can't remember if it's fixed or a certain distance from what it's tuned to, I think it was the latter, but don't quote me on that. You could perhaps analyze the circuit and connect the antenna to a more suitable point, to get it out better, unless it's all done in an IC, then it's probably a matter of putting the antenna wire close to it and hope for the best, you might get a meter or two if you're lucky... Not completely sure on how to modulate it though, it was a long time since I studied these things. Try either to find how the frequency for the superhet is generated if it's (at least partially) discrete, otherwise perhaps modulate the voltage to the IC and you might be able to get an AM signal out. Or if it's quick enough to start up, just on-off key it.