Listening to myself talk on repeaters

Sometimes I have a good enough signal to a repeater that I can key in,
but not enough to have anything other than a carrier signal get
through.  Now, if I'm trying to get attention on a repeater on, say,
the 2 meter band, how do I know whether I'm full quieting and there is
just no one listening at the moment or I'm having problems getting
through?  A friend suggested having a scanner handy with earphones to
listen to myself on the output freq.  I tried that and it didn't seem
to work at all.

I'm using a Kenwood TH-F6 to transmit on 2 meters and I have an Icom
R3 tuned to the output of the repeater I am keying up.  I don't have
any problems getting into the repeater and everyone seems to hear me
just fine.  The only thing is, I can't hear myself through the Icom
when I transmit on the Kenwood.  The Icom is functioning otherwise. 
It picks up the output of the repeater without issue unless I am
transmitting through it with my TH-F6.  For a moment I thought that my
hearing was to blame, so I dug out an old analog oscilloscope that I
had bought at a MIT flea market years ago for about $75.  I visually
watched the audio output of the Icom with the scope.  When other
operators were transmitting through the repeater I could see their
voices dance on the blue-green glowing screen of the scope, but when I
transmitted all I saw was a flat-line.

Why is my scanner deaf when I'm transmitting with a separate rig? 
Could this have anything to do with near-field emissions?  I'm
transmitting with 5 watts of power using a 7.5dB gain omni-directional
antenna.  My scanner is always within 10 feet of the antenna.

Repeater output freq:           147.000 MHz
Offset:                         -600KHz

BTW, I've talked with another ham that has experienced the same thing,
so at least I know I'm not going nuts just yet.  :)

KC2MAC