twh;
Most likely the Interference is generated from loose Pin Terminations.
Verify the Lamps' Pins are secure in the Lamp Holders.
With the Radio and Lamps on, rotate the Lamps in their Holders. Check for varying Interference.
Additionally, check for loose lead wires to the Lamp Holders.
Ballast RFI would affect the AM Spectrum more than FM, whereas Fixture EMI would affect mostly all Radio Frequency stuff - from MF (540 kHz thru 1100 kHz), through VHF and UHF.
What does the Interference sound like?
How many VHF FM Radio Channels are affected?
Is the noise level equal on all affected FM Channels?
Try "Seating" the Lamps first - rotate them in their Lamp Holders.
Then verify tight connections. Also make sure that both sides of the Lamp Holders are connected to the Ballast Lead Wire.
Verify the Lamps' Cathodes / Filaments are solid (not loosely vibrating).
Good luck.
-- Scott
