[ppppenguin]

Kat, forget about using an ordinary 4046. Must be a HC or HCT type.

I doubt you'll get much sense out of a 4046 locking to a colour burst. You need a very narrow loop bandwidth which is difficult on the 4046 if you want it to lock at all. You can't use the PSD2 for a burstlock, it just won't work as it needs a continuous reference which a burst isn't.

For Kat's application the PSD2 (sequential comparator) is the one to use. Its main problem is that it jitters when locked due to deadband effects. There are several possible cures. The simplest is a resistor from the PSD output to 0V which forces the PSD to operate slightly away from the central deadband. Another method I've used is a pair of PSDs (2x HC4046) with the feedbacks offset by 1 or 2 clock cycles. Connect the PSD outputs together so that one will track ahead and the other behind when locked. Again this avoids the deadband.

I'm sure I've got the circuits from when I used this method at 27MHz. The osc was at 27MHz, the PSDs were at 15625Hz. 27MHz was right on the outer limits of a HC4046 so only a Philips device worked. Philips HCMOS was always faster than all the others. Their HC221 monostable (consider mouth washed out again) was the only HC monostable that could be trusted at all to give consistent results. Unlike the LS221 which was usually pretty good regardless of make.

When I do SPG stuff professionally I start at 27MHz or 54MHz and derive everything from that. 27MHz to subcarrier is done with a DTO (adder and register). This is strictly speaking an approximation unless you use a more complex arrangment. I won't go into details of what I do, it's commerically sensitive. The simple method used on commerically available PAL coder chips is to reset the DTO to zero once every 8 fields. Actually the error caused by not resetting is miniscule in a stand-alone coder. It only matters in studio systems where everything has to be mutually synchronous and the relative phases of SC and H are important.