In this case the T5 that caused issues is what i'd refer to as a "test fixture" - just a
ballast & lampholders mounted on a board. so there was no sheilding or grounding or
anything on it LOL. It was simply put together (by me) to test some new lamps & ballasts
i got
At the time i uas using it not just for testing, but also for extra light in the room...
My solution was very simple, I also have some extra Magnetic-Ballasted fixtures sitting
around so i just used those instead whenever the transmitter was on, all issues were solved.

I'm sure those FM transmitters are very cheaply made, the original price on them was
around $10...but it served its purpose quite well Now that december is over it has been
put away til next year. LOL i'll know to simply keep the HF lights off if i use the
transmitter again.

It depends on when it was made where it was made for.

Anything > 10KHz is fine for lighting performance. For commercial & residential use ballasts, they originally chose band that doesn't interfere with IR remote.

20-60KHz was common, but in retail business, it can jam sensormatic anti-theft detector.
It's the little gate thing you walk through and picks up activated theft deterrence tag.  They use 58Khz. 

http://www.gelighting.com/na/business_lighting/education_resources/literature_library/white_papers/download/121879_understanding_interferance.pdf

Newest UltraMax seems to be using >70KHz to avoid interference with theft detection system.

For residential use, you're really supposed to be using FCC-B rated ballasts to minimize radio interference. There are some high quality units rated for such. 

FCC-B rated ballasts are what I use. Does anyone know why the residential ballasts are held to more strict RFI standards than commercial ballasts? It doesn't quite make sense to me. Anyways, wherever I use HF ballasts, I use B-rated residential ballasts.

Commercial environment (offices, manufacturing shops,...) usually do not require clean and quality reception of the weak radio or TV signal, while quiet homes do so...

FCC-B rated ballasts are what I use. Does anyone know why the residential ballasts are held to more strict RFI standards than commercial ballasts? It doesn't quite make sense to me. Anyways, wherever I use HF ballasts, I use B-rated residential ballasts.

I don't have many lights with electronic ballasts, for various reasons - but the ones I have had that cause radio interference (FM - I don't listen to AM) are this 4' T8 ballast and an old LOA Quad Lite CFL/adapter.

Grounding made no difference with the T8 ballast, but considering the fixture is located on the inside of an exterior wall high up on my garage and the wiring run spreads in a "T" pattern, I'm sure it's acting as an antenna.

had some terrible plastic cased ballasts from a company caled "energy savings"
they wiped out hf even with the dipole 100' away and fed with coax.could hear these 2 blocks away on 160m.they were installed in grounded metal fixtures.
had problems getting this resolved so i returned them and got motorolas.these are still dead quiet.
the energy savings guy said just live with it.WRONG ANSWER!
filed a report with the fcc.sent a sample to the local fcc field office.they said the fcc approval was void.one blew up on a ups.poor quality all around.
some ge ballasts are identical to the motorolas.

All I know is my magnetic ballasts don't seem to create any noticeable interference when running. They might crackle or hiss on startup, but that's fine.

Glad to hear you are a ham, toomanybulbs! I am as well, call sign is W8NWO. Some of these ballasts are so bad that they wipe out even broadcast radio. If people ask me why they can't get some station, I always tell them to try turning off the lights. Of course that's not always the problem, but it is in some cases.

You could also put some toroids across the line coming into the fixture to filter out the noise and HOPE it works.


Powell

I have also noticed the interference from electronic ballasts (T8 instant start). But as they fail I am replacing them with magnetic ballasts (T8 rapid start). No interference, more light, longer lamp and ballast life.

I would expect that induction lamps will more likely to cause radio interference, as electronic ballasts for fluorescent lamps operates on 20KHz (50KHz max during run-up). Induction operates on the MHz range, which is the same frequency range that radio station broadcasts.
Also, I expect that induction lamps will produces far more electromagnetic radiation than smart devices (Ie. smartphones and tablets) or any Wi-Fi or Bluetooth transmitter.

My experience with cheap computer power supplies (HF power circuit as well) is basically - the cheaper, the more interference - you can hear the noise on the radio

So what perhaps can be done - line filters added (i guess that may help... Basically 1:1 cancelling coils on the input wires to the ballast + capacitors between L-N and between them and earth

What else - in some fixtures there is quite wide "loop" formed of the wiring inside, or of the wiring and lamp. Maybe if the wires in the fixture are laid so that they wires that carry the same current are tightly together (so they cancel each other's interference), and try to get them as close to the lamp as possible, preferrably use PL-L as its ends are together

The sloppy wire installation in many fluorescent fixtures usually make them radiate way more than the induction.
With inductions it depend, what style it is about:
The "Osram Endura" style (the closed loop tubular lamp form a secondary winding around toroidal core coupler transformer) operate at about 250kHz, so they emit only one spike at LW (the main 250kHz obviously), two spikes in the MW band (750 and 1250kHz; because the waveform is rather symmetric, it have no even harmonics) and a few in the SW as well). In FM band the emission is quite weak (due to waveform shape, the harmonics fade quite steeply with frequency) and as the FM is quite spread spectrum modulation (the used bandwidth is wider than the AF useful signal), it is not as sensitive to that disturbance.
The "Philips QL" style operate at about 3MHz (so there are no emissions in LW and MW) with quite clean signal, so only the 9MHz could disturb the SW. Next harmonics is 15MHz, where is no public broadcast anymore. Higher harmonics are suppressed because of the quite narrow band lamp coupler.

What tend to be way worse are the DC output converters, so the computer supplies and mainly the LED ballasts. This is, because unlike the AC inverters (fluorescent, induction) they operate in hard switching mode (transistors turn ON when there is nonzero voltage across them), so generate quite steep pulses with quite energetic high components till really high frequencies. So for the radios these are usually way stronger interference sources (unless they are properly filtered). One thing help here: These converters do not have to operate on the exact frequency, so the operating frequency could be quite strongly modulated, so the interference spectrum could be diluted from high energetic narrow band spikes (in the frequency domain)into rather uniform noise spread evenly over all frequencies, so the equivalent disturbance is reduced by about 10dB (converter operating at 100kHz, modulated to 5% variation). But as a drawback, they cause the interference over all radio "channels", so you get disturbed less, but always.

The streets in my home town have been retrofitted with some absolutely horrible Chinese "CFL-like" induction lamps that produce lots of interference in quite wide (at least 100 kHz) bands every ~3.5 MHz, all the way up to ~18 MHz (and probably higher, but it is the limit of my receiver). They also block weak FM stations, but this is perhaps not directly on 87.5-108 MHz but at one of the IF stages (just a guess). The lamps only last a few thousand hours and often fail by producing very annoying blinking light, both random and periodic at sub-Hz to 10+ Hz. I know that they cost 450 SEK each (about 70 dollars) and I estimate that they have bought at least 1000 of them (enough for over a third of all streetlights that are managed by my local authorities). They counted on them lasting 5 years I have never seen a "real" induction light IRL (like one produced by a major company), just these.

The only fluorescent fixture that I own with an electronic ballast produce lots of noise, enough to make any many AM broadcast stations unlistenable, on all bands on LW to SW. The fixture is for one 49 W T5, all parts are metal.

I have observed that a magnetically ballasted (preheat) light can produce significant noise too, when the starter with its capacitor is not fitted. Still not nearly close enough to that of my electronic ballast.

 those ballast that use HF inveter can thow lot of RF inerference

  I notice when my 12 volt to 11O volt inverter modifed sine wave. those lot RF like you discribe
   this becase they step the voltage to HF in the mid section of the supply so they dont have to use
  those heavy bulky transformer like they would on 60 hz. then they recifi back to DC voltage again
   to High voltage Power Mosfet producking 60 Hz mod sine wave.

    as speaking of this it trash up the AM band and weak station on FM as well,

     to resolve this problem i have to make 60Hz inverter circuit and just use a transformer for my Lights and
     fan and uses that inveter larger stuff like my aircon.

oops.