Phase-locked loop filter
 

Hello all,
I've already done a post a few days ago about a PLL system I had build. The
initial problem was almost solved, but it isn't yet perfect.
In fact I made a PLL with a MC145152 IC, that I added to an existing VCO
(see
http://www.mcarsweb.com/_divers/sche...cation-note_98)
.. It works quite well but the output signal, that is fed into the VCO, is
varying a bit at a frequency of about 187 KHz
(http://www.mcarsweb.com/_divers/oscillo.jpg the vertical
scale is enlarged). I don't know if I should adjust the filter values, or
add a additional small
filter just before the VCO (with a resistor and a capacitor between the
output and the ground).

What do you think about that ?

Thanks in advance for your answers ;-)


Damien