i used 8870 i connect the hand free to 8870 i press key it not generate any out put
i check crystal frequency it is 2.9MHz
so i replace the crystal
but problem still remain
then i replace both capacitor of 33pf & crystal
but problem sill remain i change ic 8870 with a ic 8870 which work in other circuit
but the problem still remain
Change the resitor back to 100K or the input gain will be very low. How are you measuring the crystal frequency? Where is the 33pF capacitor connected?