Jim wrote:

Is it really possible to use a scanner without being exposed? I heard
from few sources that scanners produce internal oscillator signals
that can be detected. I suppose there is no "stealth" way to listen a
scanner. Any ideas?

Not sure exactly what you're asking...

You can put the innards of the scanner into a Faraday cage and just run
in the (shielded) antenna cable (perhaps with a notch filter to hammer
the IF frequency(ies)) and run out (very low pass filtered) audio
cables.

Sure you'll have some small coupling back to the antenna and audio
leads, but you could knock it way down.

It really depends on what you consider the threat to be...

I have a hard time imaging it to be an issue without serious cloak and
dagger stuff going on. (In which case, there is probably specialized
equipment...)

-Donald
--
"One ought, every day at least, to hear a little song, read a good poem,
see a fine picture, and, if it were possible, to speak a few reasonable
words." - Johann Wolfgang von Goethe