Just tried the HC version at 5 volts (I said I would try this first before the HCT) and it works perfectly. In fact it is a HC7046, which is a HC4046 with in built lock detector output, which is useful. Previously I was using phase det 1 's output to drive a transistor and LED as a lock indicator.
next job is to try and perfect the loop filter! Currently I have a lag-lead op-amp based one. I need to modulate the VCO, so the cutoff frequency will need to be low enough not to strip the modulation, ideally for best square wave response I need to get it down into sub Hz region, but will need a dual time constant to get it into lock, then use the lock indication to switch in a slower time constant. I also want to minimise phase noise! should be fun! - are you , or any one else reading this PLL experts?
next job is to try and perfect the loop filter! Currently I have a lag-lead op-amp based one. I need to modulate the VCO, so the cutoff frequency will need to be low enough not to strip the modulation, ideally for best square wave response I need to get it down into sub Hz region, but will need a dual time constant to get it into lock, then use the lock indication to switch in a slower time constant. I also want to minimise phase noise! should be fun! - are you , or any one else reading this PLL experts?