Can an employee secretly record my conversations and send them to my boss to tryand get me fired?

PA has some of the most stringent recording laws in the country. While the majority of states follow the "1 party consent" rule, PA is an "all party consent" state. This means that all parties to a conversation (either in person or on the telephone) must consent to it's recording. To put it another way, the person doing the recording must be a party to the conversation and all those being recorded must consent to its being recorded. 

That above holds true unless there is no expectation of privacy.  In other words, was the conversation considered to be private? Almost all telephone conversations are presumed to be. However, in-person conversations are not necessarily private. As a general rule, in-person conversations which can be naturally overheard (i.e. without use of any special devices) are not considered private communications. So where you record matters. If it's in someone's private office all people being recorded must agree to it; if it's in the lunchroom than no such consent is needed.

Failure to obtain unanimous consent can result in a personal injury lawsuit, and in some cases criminal charges as well. The fact is that recording a fellow co-worker secretly, may well result in the employee who is doing the recording, being terminated themself.