Lumatek Ballast you have heard of them, now get yourself one. Lumatek 600 Watt Ballast 240v Dimmable is a fantastic piece of gardening equipment. Several studies have shown that the output form Lumatek ballasts is 5 - 10% greater than other electronic ballasts. They are completely silent and give off considerably less heat than traditional "coil and core" ballasts. Lumatek ballasts have been redesigned several times since their introduction. This new design (the purple ones) have eliminated the electrical interference that plagued the original models. You can confidently grow and use you cordless phone or watch satellite tv without static.

Specifications:
Electronic ballast for 600W HPS or MH lamp
Voltage: 230V 50/60Hz
Current: 2.70A
Input power: 620W
Output power: 600W
Power factor: >0.99
Voltage range: 165 to 265V
THD: < 8%
Lamp CCF: < 1.7
Operating frequency: high frequency
No audible noise, no flicker
Environment temperature: -25 to 50°C (-13 to 122°F)
Enclosure temperature rise (Δt): 35°C (95°F)
Environment IP require: >IP23