But can I just Tap into the Mic's line like that? I figured it would change the impedance that the Mic element see's and mess up my audio??
At this point I would settle for easy recording and forgo the oscilloscope if need be, but will the Mic tap really work with no issue's ?
I think Steve (WB2WIK) is right. The FT-857 uses a low-impedance dynamic mic (MH-31, nice sound), and the spec for the transmitter says:
. . . Microphone impedance: 200 - 10K ohms (nominal: 600 ohms)
So they've designed the FT-857 mic preamp with a fairly high input impedance, and lots of gain.
A second high-impedance amp, driven by the same microphone, should work fine to get your mic signal into a recorder.
This is a good application for a small Behringer mixer -- use its mic preamp on one channel, use a second channel to "ride gain" on the received audio from the DATA OUT pins, and mix the two channels into an output that you feed to the recorder.
RFI might be a problem -- be warned.