philips dimmable ballast followup

[sm_jamieson]

So, regarding the philips dimmable dual ballasts that are churning out RF a= nd killing radio 4 FM on a radio 1.5 metres away.

I sent a note about this to BLTdirect who passed it on to philips. A reply = from BLTdirect included a PDF about installing philips ballasts, which stat= es that it is assumed that the ballast and wiring is inside a type 1 enclos= ure, which apparently means an earthed metal box.

I have tried ferrite cores on the wiring from the ballast which made little= difference. A large ferrite with the radio mains cable looped through it s= everal times makes the radio just about OK, but that is not solving the pro= blem at source.

The interference is not quite as bad on other radio stations so there must = be a peak around 92MHz. I think most of the interference is from the ballast itself.

The other thing that seems a bit weird but not surprising since the whole t= hing is an RF transmitter. If I connected a short length of wire to the met= al ballast body and held it straight and touched the other stripped end the= n the effect of my body virtually removed all the interference. Trouble is = I cannot stand there and hold it. I wonder it some capacitive circuit could= simulate this.=20

What a flippin' pain !

Anyway, it looks like the whole thing is going to have to go in an earthed = box. Anyone got any second hand 4 foot empty fluorescent luminaires, or know whe= re I can get them ? Otherwise I will have to buy cheapo lights and replace = the guts. I would probably use the existing connector for one tube and conn= ect the other one on short flying leads to push-on end caps. I have an old 5 foot that could be cut down but it has plastic end caps whi= ch would probably let the RF out, so that may be no good.

Wish I had got the osram !

Simon.

[meow2222]

thing is an RF transmitter. If I connected a short length of wire to the m= etal ballast body and held it straight and touched the other stripped end t= hen the effect of my body virtually removed all the interference. Trouble i= s I cannot stand there and hold it. I wonder it some capacitive circuit cou= ld simulate this.=20

usually means its not earthed

here I can get them ? Otherwise I will have to buy cheapo lights and replac= e the guts. I would probably use the existing connector for one tube and co= nnect the other one on short flying leads to push-on end caps.

hich would probably let the RF out, so that may be no good.

Why not just use screened wire for the tube leads

NT

[Brian Gaff]

Thing that worries me is that 92Mhz is unlikely to be the fundamental of the oscillation. Its probably creating havoc from a much lower frequency due to the shape of the driving waveform being s Square or triangular or just very jagged.

You need some person with a scanner or similar wide band radio to reveal the true state of play.

Brian

[sm_jamieson]

le thing is an RF transmitter. If I connected a short length of wire to the= metal ballast body and held it straight and touched the other stripped end= then the effect of my body virtually removed all the interference. Trouble= is I cannot stand there and hold it. I wonder it some capacitive circuit c= ould simulate this.=20

Yes, that was without the case being earthed. The earth terminal is connect= ed though. The strange thing was that earthing the case did not have this e= ffect. Which makes me wonder about the earthing of the whole setup. I will check t= hat later today.

where I can get them ? Otherwise I will have to buy cheapo lights and repl= ace the guts. I would probably use the existing connector for one tube and = connect the other one on short flying leads to push-on end caps.

which would probably let the RF out, so that may be no good.

That would be OK, but there seems to be emissions from the ballast as well = and I'd want to make sure the connections between the ballast and cable are= all screened, so easiest to screen the whole caboodle. Simon.

[sm_jamieson]

and killing radio 4 FM on a radio 1.5 metres away.

y from BLTdirect included a PDF about installing philips ballasts, which st= ates that it is assumed that the ballast and wiring is inside a type 1 encl= osure, which apparently means an earthed metal box.

le difference. A large ferrite with the radio mains cable looped through it= several times makes the radio just about OK, but that is not solving the p= roblem at source.

t be a peak around 92MHz.

thing is an RF transmitter. If I connected a short length of wire to the m= etal ballast body and held it straight and touched the other stripped end t= hen the effect of my body virtually removed all the interference. Trouble i= s I cannot stand there and hold it. I wonder it some capacitive circuit cou= ld simulate this.=20

here I can get them ? Otherwise I will have to buy cheapo lights and replac= e the guts. I would probably use the existing connector for one tube and co= nnect the other one on short flying leads to push-on end caps.

hich would probably let the RF out, so that may be no good.

Well, BLTDirect have been very helpful, and have accepted a return of the p= hilips ballasts, so I'll get to try the Osram ones after all.

Simon.

[Dave Plowman (News)]

I hope it sorts it for you, but I'd be surprised if two major makers were so different in respect of RFI.

[sm_jamieson]

So would I, but another poster (can't remember who) has described a ballast set up exactly like mine, with no interference issues at all. He said he could put the radio right up against the ballast and no interference at all. Unless his ballast was non-dimming and mine is dimming, and that accounts for the difference. We'll see. Simon.

[Dave Plowman (News)]

That was me. I only tried it after you mentioned it.

My Osrams are many years old so may not still be current. The dimming on them uses some form of internal DC controlled device as the dimmer only varies LV DC. There are likely other ways of doing it which may produce more EFI - I dunno.

[sm_jamieson]

The current ballasts are 1-10V and simply dimmed with a potentiometer between two terminals, a reference voltage being supplied on one terminal. Could you see what the model number is as printed on the ballast ?

Cheers, Simon.