Add a ferrite filter to the digital ballast AC line input and ballast cord output and suppress ugly interference to surrounding electronic devices (yours and your neighbors)! Order 1 set for each ballast.
You get a ring filter (1.4" ID) for the AC power line and a snap on filter (3/4" ID) for the lamp cord. Wrap as many turns as possible on both cables as close as possible to the ballast.
Ballast shown is a Lumatek LK400.
All ballasts in a particular location must have a filter otherwise RFI may not be suppressed to a measurable value. Suppresses RFI in range of .15-10 MHz.
50 ohm coax to 75 ohm balanced output baluns are useful for low (< 1 wavelength) dipoles exhibiting 75 ohm characteristic impedance or for matching to balanced ladder line whose endpoint impedance is near 75 ohms.
50 ohm coax to 75 ohm CATV coax connections are easily done with a 1.5:1 unun with SO-239 connectors on input and output. Likewise 50 ohm coax to unbalanced verticals or loads near 75 ohms can be matched with a 1.5:1 unun.