The two 3-500zg's I put in my Henry 2K Classic X show little color at 1 KW on data modes, modest color, dull red to low orange at 1.5KW mode. The former is with 3 Kv on anode and the later is with 4 Kv on the anode and approximately .800 current on the plate. Of course this amplifier had a squirrel cage blower with plenmty of air going through. The grid is showing