Be aware of power supply noise rejection- or the lack of it.
The 4046 phase comparator etc - they all have VERY LOW almost zilch power supply noise rejection, IME.
Same with CMOS gate oscillators etc. ADF4002 is a good chip. , Agreed Bob. I'm assuming this design is on a multilayer PCB ? On 23/02/2022 12:09 am, Bob kb8tq wrote:
Hi Best guess: Your 10 MHz (for whatever reason) is being turned into a fast edge square wave. That’s dumping current spikes into the supply and ground on your board. You have a really wide spectrum as a result ( usually well up into the GHz region). That “stuff” is going here / going there. Some of it is getting into your amplifier / filter chain by one route or the other. It looks like modulation because of the filtering in your multiplier chain.
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