Oh I do wish I could find one of these. I've seen them on eBay occasionally but usually just the lamp globe or base, rarely with the ballast as well

Such system is becoming rare indeed.

I must look after it then. I had a habit of trying to light other lamps using the RF field it produces, but it has some intelligence and detects the loading is incorrect shutting down the ballast. However, it will keep trying but I have heard its easy to kill the semiconductors with such behaviours.

I certainly wouldn't recommend running the QL system without its bulb, this stresses the driver too much. If you really want to use the antenna as an EM source (QL's antenna generates both electric and magnetic fields) to excite loose lamps and discharge tubes without running the risk of busting the transistors, then connect a standard GLS incandescent lamp in series with the antenna, this resistive load will absorb the reflected power. I don't remember the exact rating of the GLS lamp needed for the 85 W driver, it's either 100, 150 or 200 W. You certainly can do some tests and see what works best, that resistive impedance should not be too low (not enough dissipation of the reflected power) nor too high (too much voltage drop added to the circuit).

Interesting Max, Never thought of adding a resistive load to the antenna circuit as an attenuator. Although a common practice on the supply side to limit current draw when testing electronics in general. I'll keep this in mind if experimenting.