Transmitter to improve

I found the idea excellent and this system is practical, however, despite the tricks to set up the transmitter as advocating an FM frequency that connect to get a good reception and the antenna retracted, the quality is very average sometimes execrable and interfered with radio stations.

I once had a tape that looked perfect quality but after a while the sound of the tape ended up being heard too significantly, so this device could eliminate this drawback.

Note that I have tried several days in town, perhaps near the cities it is more efficient?
However audio quality is very average. I was very disappointed, not the height of the cassette.