tda7000 receiving AM modulated signal..
 

hello

I have an FM receiver question regarding the philips tda7000 chip. I have
been able to tune the reeiver to about 23mhz. when i turn on my heathkit RF
generator tuned to 23 mhz (+/- the IF of 76khz) i pick up a signal on the
chips output that responds to small changes in frequency around the center
of the band.

the part i can't figure out is that when I turn on the rf generator's 400 hz
modulation (which I am nearly positive it is AM modulation) I pick up the
400 hz audio signal on the tda chip's output. I can't figure out how the
chip's built in quad detector would be able to so cleanly pick up the AM
modulation. I was under the reasoning that the quad detector would be able
to get rid of most of the modulations but it doesn't. the 400hz audio signal
comes through very cleanly.

Any ideas?

Thanks,

jeff