Just in case you still haven't solved your issue . . . .
Quoted from
AVS Forum
POST:"Hi to everyone. I've been reading a lot of helpful posts on this forum for a long time, and now it's time for me to make my first post. I've been having a terrible time with reception of WRC in Washington DC. . . . . . .WRC bounces back and forth between 60-83 with occasional dips into the 50's or momentary total signal loss."
REPLY:"You should post this in the Baltimore-Washington thread. Your problem is not unique out where you are with getting the digital signal for WRC-DT NBC 4 which is broadcast on UHF 48. The reason is that there is a low power analog station WAZW-CA 48 located in Winchester, VA which interferes with the digital reception of WRC-DT. The FCC data for WAZW-CA is at
http://www.fcc.gov/fcc-bin/tvq?list=0&facid=57911. You need to try to block out the interfering signal from WAZW and/or get a better ATSC tuner. Again, take this to Baltimore-Washington thread."