Hi Rich, From the PLL diagnostics page at: http://www.proaxis.com/~boblark/dig_pll1.htm U104-7 5 Volts This means LD=Lock; 0 to 4V=Out-of-Lock U7-11 5 Volts This means LD=Lock; 0 to 4V=Out-of-Lock Mike KD7TS