Fluorescent lamps are already RF noise sources. Modifying a tube to modulate the noise would be a useful eavesdropping device. If you used a digital modulation mode with a scrambler (the pseudorandom device that makes the number of 1 and 0 bits roughly equal) the emissions would look just like standard white noise to receivers that didn't know the decode pattern.

Now all you have to do is to get your modified lamps into the supply chain for lamp replacement in the secure area.