T8 Lamps
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| Sep 20th 2011, 14:56 | |
W1MGTotal Topics: 0 Total Posts: 0 |
A member asks... I’m thinking of changing the 4ft. lamps and ballasts in my radio room and over my workbench, from T12 to T8. Will I have a problem with the RF from the T8 ballast? I do a lot of work on local repeaters and don’t want any stray RF getting into my test sets. |
| Sep 20th 2011, 14:57 | |
W1MGTotal Topics: 0 Total Posts: 0 |
You may… RFI from fluorescent lights can be a function of the ballast. Newer T8 bulbs usually involve electronic ballasts, which can be a significant source of RFI. They typically operate under Part 18 as an RF Lighting device. One thing to look for is whether or not the ballast is rated for consumer or non-consumer applications. The emissions limits are lower for consumer Part 18 RF lighting devices. These are the only electronic ballasts that should be used in a residential environment. Although there is a reduced probability of RFI from a consumer rated ballast, it is also important to understand that the possibility still exits. The lower emissions limits of these devices do not completely eliminate the possibility that interference can still occur. Unfortunately, we’ve seen many non-consumer ballasts being marketed and sold to unsuspecting homeowners by many home outlet stores. In some cases, these non-consumer ballasts may be labeled as Part 18A. Be sure that whatever ballast you use, if it’s an electronic one, is labeled for consumer use or Part 18B. Older non-electronic ballasts may not be as common as they once were, but can be less prone to RF interference when functioning properly. These ballasts operate under Part 15 as an incidental radiator and therefore do not carry an FCC label. These can be another option when attempting to maintain an RFI free environment. |
| Sep 20th 2011, 15:53 | |
KE8DOTotal Topics: 0 Total Posts: 0 |
You can do what I have done in my basement workshop/ham shack. I have 2 lighting circuits, one using regular light bulbs and one using fluorescent lighting with T8 bulbs. I can turn on one circuit at a time or both. |
| Sep 23rd 2011, 14:39 | |
W0RSBTotal Topics: 0 Total Posts: 0 |
We have 5 fixtures, each with 2 4-foot T8 tubes in the utility room adjacent to my shack. I hear absolutely nothing from them on HF. The fixtures (with ballast) are whatever is sold at Home Depot. |
| Sep 5th 2013, 02:15 | |
bobripleyTotal Topics: 0 Total Posts: 0 |
I have been troubleshooting RFI issues in my workshop that is equipped with two independent banks of 4 each dual T8 fluorescent light fixtures. I found a couple of ballast that were not Part 18B rated and where noisy. Those were replaced. Using an old pocket sized 6 transistor radio from the 70s as a RFI sniffer I am finding that most of the noise is not coming from the ballast themselves but from the ends of tubes where they seat into the connectors that is driven from the output of the ballast. It is not both ends of the tube but usually from just one end. Any idea how to tackle this problem? I tried different vendors of T-8 4' tubes but they all exhibit the same symptom. Thank you Ripley |
| Jun 17th 2014, 18:16 | |
AC0XUTotal Topics: 0 Total Posts: 0 |
I have done testing on T12 T8 and T5 shop lamp fixtures purchased from Home Depot. I have found that T12 are consistently noisier than T8 which are consistently noisier than T5. People say that the electronic ballasts are noisier than the transformer ballasts, but I have not found this to be the case. Fluorescent tubes are nonlinear devices and they produce high frequency EM even when driven at 60Hz (really 120 Hz). Possibly, a transformer ballast system could be combined with appropriate capacitors to reduce ringing, but such systems don't seem to be made. I recommend going with the T5's. Use the high intensity bulbs for a few more dollars if you need a lot of light - they are really bright. With all of the above, I have the following recommendations: 1) Use only fixtures with metal shells (some are plastic - avoid these). 2) Be certain to ground the light fixture case. If you fail to do this, all of the fixtures will emit considerable RFI. 3) Little RFI appears to come from the fluorescent tubes themselves. It mainly comes from the wiring. Ground the case containing the wiring and the ballast, and you eliminate most of the emissions. |
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