OK -- lots of experimentation tonight.
The upshot is at least in the Raleigh zip, as soon as the WUNC (25 / 11.1, 11.2, 11.3) get strong enough for the AM21 to recognize a signal is there, the scanning locks up.
First I tried the varying lengths of coax -- no stations.
Second I tried the antenna without the amp in the middle of the room -- picked up one channel.
Third, moved the antenna to the window -- locked up -- Seems my second strongest channel is WUNC...
Any amplified location caused a lockup... Started adding splitters to the amplified antenna, could not get it to not lockup.
Had to resort to pulling the antenna connection when scanning got to 65% (66% locks up), and plug it back in at %67. My first try, I got 5 stations, my second try I got 8 -- including the two that are essential for my wife.
If I had a true unidirectional antenna, perhaps I could point it at the two locations I am interested in, which are more than 90 degrees away from WUNC and get more.
These experiments, while not conclusive at all, lead me to believe that it is something in the signal of WUNC and not the strength of the signal. The first station I picked up was stronger than WUNC, and the scan completed fine.
I will continue looking for solutions that allow me to pick up all 36 stations I get when my antenna is directly connected to my TV.
Cheers,
Scott.