[sdiy] crystal bandpass filter / amplifier with CD4049UBC

[Bert Schiettecatte]

hi all,

i've been trying to build a very narrow and steep bandpass 
filter / amplifier using a couple of hex inverting buffers, 
some 1M resistors and 10Mhz crystals. 

I need to amplify a very small 10Mhz sine signal, but it is 
burried in noise. I've put a 1M resister in parallel with 
each buffer and a crystal between buffer inputs / outputs. 
I've made 6 stages of filtering / amplifying using a single
4049. The circuit idea comes from one of the elektor circuit 
books (306 circuits or something). 

the problem is that the circuit is oscillating :( i can't 
stop it.. anyone have an idea why?

thanks
bert