OK, I'm thinking again....sorry LOL
So you have a repeater and an HT that is near the receive limit of the repeater. Why doesn't it oscillate? You transmit with the HT, the repeater receives the signal activates the transmitter, desenses the receiver and the transmitter stops and then the HT signal is received again and it oscillates back and forth on this.
Is there a delay or something designed in a repeater to prevent this?
I also have observed that there is a point where you can activate the repeater and keep it up but you can't push your audio through it, not ever scratchy audio, it's basically blank. But get a bit closer and you get scratchy audio. I assume that's when you are able to overcome the desense of the system?