This is a quiz! New amp using 3CX3000A7. No band switch, new plate blocking cap (.0019uf/15KV). Tube fil turned off. When I adjust the HV to more than 4-4.5 KV it eats the glitch resistor. (10 ohm) With a 22k glitch resistor it lives.I repeat, the filament is turned off! Dennis W7JX