Can this FM detector even work?

[Bobby Dip]

I have some more info. I switched my generator from FM to AM, and this circuit seems to demodulate AM just as well as FM. Also, I found that the IF cable from the tuner was pinched in the sheet metal. After fixing that, I have real audio from the channel 3 output on my cable box. The audio sounds fine as long as there is no digital lettering on the screen. There is a nasty buzz when there is lettering on the screen. Our first TV, some forty years ago, was an old B&W set that did the same thing. I was never able to eliminate the buzz, and finally decided it was a design limitation of the set. Back in those days only the news shows had digital graphics, so it wasn't that big a deal. Is this 'buzz' problem common on old TVs? Is it a design limitation as I assumed?

Bob D.