Hi X and all,
Now you've gone and one it, ask a simple question and before long they start discussing nuclear physics. OK, back to the beginning with a simple answer that should clear up the confusion.
"Scanners typically have poor selectivity."
Great Lakes means "front end" selectivity which for all practical purposes is absolutely nil. The RF amp is so broad it receives "DC to light", that is everything at once and the selectivity comes in later, primarily in the last IF amplifier chain.
It's the RF amp being overloaded to the point of cut-off that's causing the "blackout" of signals, an extreme case of "desense" or de-sensitization. When the transmitter is farther away the condition is reduced so signals are received but at a much lower than normal level.
Now if you want to REALLY confuse people you may discuss transistor beta, operational curves and amplifier bias. Solid state engineering theory you >need< to understand what's going on inside the box. In other words you must learn Greek to impress like a geek, better yet use scientific font in your posts and fill them with advanced mathematics. (;->)
I hope you have learned your lesson, when you ask the time some will tell you how to build a cesium ion laser atomic clock.
