Even though I say you should use a better antenna, if set up properly, you should still be able to receive and transmit even with the window mount antenna, they just do now allow you to actually receive and transmit to the full capability of your radio. They were not designed for the practical use in mind, but more so for the looks.
1. For grouding the radio, you can ground it just about anywhere you like. I usually sugest running the power and ground right off of the battery.
2. When you say you grounded the receiving end of the antenna, did you mean that you grounded out the metal part of the antenna, the part on the outside of the window? Please clarify. If the actual antenna is grounded, it is like having no antenna at all. I have not used this particular antenna and am not sure if that antenna needs to be grounded. Unless the instructions from the antenna package said so, it will not need to be. On a regular antenna application, the base where the antenna is screwed into is grounded and the antenna itself is not.
Make sure your PA/CB switch is set to CB, they are easy to bump and not notice that they are set to PA. Turn your squelch all the way counter clockwise.
3.You don't have to use inline noise filters. People use those when they get like alternator noise coming through their radio, which will be a whining sound when you are acellerating, or turning your airconditioner blower between fan settings.
This is why I usually suggest people run their cb radio power straight from the battery, because it lets the batterywork as a filter, but you can try an inline filter if you don't want to go that route. But first, you have to any determine if you have alternator noise before you need to worry about it.
If none of this helps, please let me know. You can post here or email me at [email protected]