are currently on back-order so was wondering if anyone has a suggestion for an alternative, basically what are the key characteristic required in the circuit there?
Could you substitute a different capacitance? 180p or 270p? Different type of capacitor?
220pF NP0/C0G ceramic with a tolerance < 2.5%
Unfortunately all my searching turns up non-stocked items at Mouser. Plenty available with 5% tolerance though.
FYI, smallbear has all sorts of polystyrene caps in stock.