I've wired two dual dimmable ballasts (philips) on top of two runs of kitchen cabinets (4 x 36W tubes). Not wired up the dimming potentiometer yet. But I cannot now use the mains FM radio by the kitchen sink now due to rather a lot of RF interference. The distance from the radio to the ballast and tubes is around 1.5 metres. Now fluoros can cause interference but I don't remember them causing this much. The ballasts are wired up with short wires where required, and TWE running to the other end of the tubes. The tubes are held in metal clips, so no earth plane running alongside. Its not obvious if the RFI is coming from the ballast or the tubes and whether it is being picked up by the main cable of the radio, although moving the radio mains cable around seems to vary the interference. What is the best way to deal with this ? Simon.
cabinets (4 x 36W tubes). Not wired up the dimming potentiometer yet.
a lot of RF interference. The distance from the radio to the ballast and tubes is around 1.5 metres.
the other end of the tubes. The tubes are held in metal clips, so no earth plane running alongside.
it is being picked up by the main cable of the radio, although moving the radio mains cable around seems to vary the interference.
Make sure ballast case is earthed. Try threading a ferrite core on the mains supply to the ballast, positioned near the ballast. You could also thread the wires to the tubes through one, but they must all go through the same one.
It might be that the FM signal is weak there anyway. It would be interesting to see how far away you have to move the radio for the problem to go away. Does the radio have provision for an external aerial connection? Does it make any difference if you pull out the mains lead and run it off internal batteries (if it can)?
kitchen cabinets (4 x 36W tubes). Not wired up the dimming potentiometer yet.
rather a lot of RF interference. The distance from the radio to the ballast and tubes is around 1.5 metres.
to the other end of the tubes. The tubes are held in metal clips, so no earth plane running alongside.
whether it is being picked up by the main cable of the radio, although moving the radio mains cable around seems to vary the interference.
I dont have the batteries to try that at the moment.
The ballast case is not earthed directly but there is a earth terminal for on the mains supply. Maybe that is not connected to the case. Earthing the case is the easiest thing to try so I'll try that first.
Then trying the ferrite beads / clamps. From doing a quick internet search, this has solved the problem often, including in cars with HID lamps. When you say the wires to the tubes must go though the same ferrite, do you mean all 4 wires, or the pairs of wires to each end of the tube ?
I am aware that switched mode power supplies have a ferrite lump on the cable to suppress RFI. Apparently you can get "residential grade" RFI suppressed high freq ballasts (at least in the US), and I guess maybe these just have ferrites on the cables.
I've known these electronic ballasts to do all kind of mayhem, including completely confuse a vcr on the other side of the wall in the sitting room, and make DAB sound like boiling mud. I'm old fashioned but the minute I see electronic on something, I think switch mode alarm red alert! I never had problems with good old fashioned ballasts provided the tubes were good and the capacitor good. Of course they don't like dimmers, but dimmers themselves are a source of interference as well unless they are of the zero point switching type. Brian
Unfortunately I've found that even things with the CE mark are naff. The worst offenders are the chinese wall warts, particularly those with usb connectiors on them for charging mp3 players etc. I was told once that after approval the shipment missed out all the suppression components to save money. Brian
kitchen cabinets (4 x 36W tubes). Not wired up the dimming potentiometer yet.
rather a lot of RF interference. The distance from the radio to the ballast and tubes is around 1.5 metres.
to the other end of the tubes. The tubes are held in metal clips, so no earth plane running alongside.
whether it is being picked up by the main cable of the radio, although moving the radio mains cable around seems to vary the interference.
the mains supply. Maybe that is not connected to the case. Earthing the case is the easiest thing to try so I'll try that first.
It's probably connected to the terminal, but no harm connecting direct to the casing too.
this has solved the problem often, including in cars with HID lamps.
mean all 4 wires, or the pairs of wires to each end of the tube ?
All 4 wires. The current won't be balanced through the core unless you take all the wires through it. Again, you want it as near the ballast as it will safely go. It effectively shortens the RFI transmitting antenna to the length of cable between the ballast and the core. If you get a big enough core, you can loop all the wires through the hole more than once, which will improve its effect even more.
to suppress RFI. Apparently you can get "residential grade" RFI suppressed high freq ballasts (at least in the US), and I guess maybe these just have ferrites on the cables.
Their RFI emissions regs may be different than in the EU, perhaps not requiring inbuilt supression in commercial environments. We do have some exceptions in the EU, e.g. equipment to go into telephone exchanges - it's up to the exchange owner.
kitchen cabinets (4 x 36W tubes). Not wired up the dimming potentiometer yet.
rather a lot of RF interference. The distance from the radio to the ballast and tubes is around 1.5 metres.
running to the other end of the tubes. The tubes are held in metal clips, so no earth plane running alongside.
whether it is being picked up by the main cable of the radio, although moving the radio mains cable around seems to vary the interference.
on the mains supply. Maybe that is not connected to the case. Earthing the case is the easiest thing to try so I'll try that first.
this has solved the problem often, including in cars with HID lamps.
mean all 4 wires, or the pairs of wires to each end of the tube ?
The ballasts are dual, and there are 7 connections: (ballast A pair to far end)(ballast A)(common ballast A+B)(ballastB)(ballast B pair to far end) The way I have wired it has the common to ballast A connector, then a single wire from ballast A connector to ballast B connector (since the connectors have dual push-in connectors at each terminal). All the dual runs are TWE with the earth stripped out.
So I'd need a core of internal diamter about an inch to get round the whole lot. Where would I get a core that size ? Also, how tighly fitting does the core have to be ? If I ran the cable thought a core of internal diameter 1 metre it obviously would not work.
I suppose a core around each "half" with the common wire inside both cores would be possible.
If I wanted to wind through a ferrite core more than once I'd have to strip the wires out of the TWE outer sheath, which would be a pain but could be done.
Would putting the ballast and cables inside a metal box like a standard fluorescent luminare do the same job as the cores, or might you need a metal box and the cores ?
Sorry about all these questions, I know little about the EMC side of things ! Simon.
kitchen cabinets (4 x 36W tubes). Not wired up the dimming potentiometer yet.
rather a lot of RF interference. The distance from the radio to the ballast and tubes is around 1.5 metres.
running to the other end of the tubes. The tubes are held in metal clips, so no earth plane running alongside.
whether it is being picked up by the main cable of the radio, although moving the radio mains cable around seems to vary the interference.
on the mains supply. Maybe that is not connected to the case. Earthing the case is the easiest thing to try so I'll try that first.
this has solved the problem often, including in cars with HID lamps.
mean all 4 wires, or the pairs of wires to each end of the tube ?
If you have the time, could you explain a bit more about balanced current ? What happens if the current isn't balanced ? And is this just for for cables to the tubes or for the mains supply as well ?
You see single wires wound round ferrite rings, but maybe this is just for single-conductor antennas.
And if you wanted to pass a mains supply (live and neutral) though a ferrite several times, would you wrap each conductor several times round opposite sides of the core, or wrap them as a pair ?
I'm wondering if you have a faulty unit? I've just tried a FM portable close to my dimming Osram units - not a hint of interference, even with the receiver between stations.
Stuff from China is marked with the CE mark, but according to the Chinese it's not the European CE mark, but stands for "China Export". odd how similar it looks to the Euro CE mark though...
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