electronic ballast causing static

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shawelectric

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A lady remodled her kitchen and had two four foot flourecent lights put in. These lights are causing interference with the reception of the rabbit ears on her tv. The lights were not professionally installed. The pollarity was reversed. I fixed that, and connected them straight to the pannel. However, the problem still persists. Do you think it could be caused by hermonics?
 
Just a guess ... these fixtures are cheap home center fixtures?

Could be just very cheap ballast that are sending out a lot of radio frequency interference.
 
Rabbit ears don't have much surface area exposed to the transmitted signal, hence the induced signal in the lead to the TV is tiny. If this tiny signal is already down at the threshhold of detection of the TV tuner, then subtle changes in the overall "electromagnetic soup" of all emf in the vacinity of the rabbit ears can have a disproportionately large change in the performance of the TV.

Iwire suggests the idea of ballasts that create broad spectrum noise. . .like trying to listen to a single speaker while a crowd around the speaker is also chattering amongst themselves.

I have even had situations where the simple change in the physical configuration of the branch circuit cables have been what has caused the change. The local branch circuit cables will reflect emf and / or cast shadows.

Changing the antenna location, changing to a different antenna, re-orienting the antenna and / or amplifying the antenna is the key.
 
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There are two means that interference leaves the lamp. One is RF radiation as radiated radio waves. The major source of this is the arc discharge in the lamp and it is directly radiated from the 4' length of the gaseous discharge in the tube. The second source is conduction thru the power wiring to the fixture. There will be both conducted noise along these lines from the lamp fixture to the radio or TV, and additionally there will be RF radiation from these conductors.

If you carry around a purely battery powered radio with no direct connection to the power wiring you will hear noise from the lamp. This is RF radiated noise.

In the case of electronic ballasts there will also be low frequency noise from the about 30 kHz pulses used to excite the lamp and maybe up to the 10th to 20th harmonic, 600 kHz. There may be some ballasts up to 100 kHz for a base frequency.

Noise coming out thru the power wiring can be reduced with a line filter in the fixture. Radiated noise has to be reduced by shielding of the entire fixture and lamps.

Even non-electronic ballast fixtures produce a lot of RF noise from the gas discharge in the lamp.

Generally there is a lot to be gained by a noise filter in the fixture immediately at the input to the ballast.

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I had a similar issue at a dog kennel. The gent had rabbit ears in the attic and they installed a new electronic ballast light by someone. We tried filters etc, I happen to have an nonelectronic version of the same light from a previous job and once that went in it corrected it....maybe not the best diagnostic solution but it worked,
 
shawelectric said:
A lady remodled her kitchen and had two four foot flourecent lights put in. These lights are causing interference with the reception of the rabbit ears on her tv.
Click to expand...

My kitchen light (2 x 4 ft) does this too, but I dont have bugs ears, I have an outdoor aerial.

This flippin florrie generates a load of RF on the same frequency as channel one on the telly. Confirmed using the Sadelta RF field strength meter. Munts the picture something chronic. But, as florrie go, its a pretty fixture, so it's stayed on the ceiling...

Should do something about it really, I'm always getting earache for it from the missus. An RF choke on the supply lines would be the first thing I'd try.
 
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