Cable line tap splitter aka directional coupler

[JohnnyM]

I am fairly certain this is what I need to fix my signal issues to my cable modem. I don't know where to find one.

I've tried circuit city and radio shack so far, they are the only two that are close by. Any ideas what stores or even what kind of stores would carry these?

 

[coopntex]

I got my last one at walmart.