Yes, squelch threshold.
That's where I was talking about using a digital pot, but that still may not add much resolution. If understand Mike's description correctly, it appears anything > 4k7 has no effect on the threshold.
As you noted, the CH adjustable feature is very coarse.
I *think* the default squelch at boot time can be set in the RSS, and then stored in the codeplug, but I suspect any adjustments made after boot up are held in register(s) in the Hitachi itself until rebooted.
