It sounds like there is some electrical noise interference that would
not be "fixable". If though, we reconfigure the way that they are
connected together, we may be able to avoid the noise.
Instead of allowing the antenna signal to "pass through" the 625 we will skip it.
After following the directions, switching between satellite and antenna will be done by selecting on the SANYO "Input 1" for satellite, and selecting "Ant" for antenna. K?
From the 625 Tuner 1- using RCA cables (a.k.a. composite cables, or red, white, yellow cable), connect to "Input 1" on the Sanyo TV. To see composite cables go to http://www.wowvision.tv/settingsandconnections.htm
Next, remove the coaxial cable between the Sat box and TV. (Sanyo "Ant. In" port and 625 "Out to TV" port) Set that cable aside.
Now, remove the incoming antenna cable from the 625 "Ant. In" port, and connect it to the Sanyo's "Antenna In" port.
Finally, scan for channels and check for the presence of CBS.
Once verified, test the TV by turning off and on.
Turn on the satellite receiver and switch Sanyo to "Input 1" to verify sat picture.
I believe this solution will satisfy your needs. Please let me know if it doesn't work, and I will need to talk to you about signal strengths, again.