[RFI] Electronic Lighting Ballasts

kr7o at vhfdx.com kr7o at vhfdx.com
Sun Jan 3 09:23:45 EST 2016

I am currently in the process of replacing old T12 lighting with T8 
fixtures and have spent quite a bit of time testing the RESIDENTIAL 
fixtures I found at Home Depot and Lowes.  Plus one LED fixture by 
Utilitech from Lowes.  I was encouraged to find the boxes marked with RFI 
filtered or similar on the T8 fixtures.  I found the Lithonia to be 
terrible.  It had objectional RFI on 80, 40, 30M and terrible RFI on 15 and 
6M.  6M had a 30db rise in the noise floor in a 2.5 KHz bandwidth with a 
-93dBm noise level and 15M was similar but I did not measure the exact 
level.  This was using a 14dBd 6M array about 50' away, a small tribander 
about 70' away and low band antennas 200'+ away from the fixture.  Tests 
with a 50 ohm resistor 3-4' from the fixture were worse.

The Metalux (I think that is the brand) fixture from Lowes showed no rise 
in the -140 to -145 dBm noise floor using a 50 ohm resistor in the shack 
during initial testing.  After a bit more testing and tuning through the 
bands I was able to detect weak switch mode power supply traces on the 
waterfall at a few spots on the low bands.  but they were not detectable on 
my external antennas since the noise floor is much higher.  After twisting 
the balast leads and putting 6-7 turns on a #31 ferrite I can only barely 
detect any traces any more even with two fixtures turned on.  The handful 
of traces on 160, 80, 40M were a maximum of -140dBm into a 50 ohm resistor 
3-4' from the fixtures and only 3b above the noise floor.  Another turn or 
two might clean up the residual traces, but I used up the supplied 
leads.  I may have enough extra when the fixtures are installed.

I haven't installed the Lowes fixtures yet (will be a total of four 
fixtures), but I don't anticipate any problems.  Did I need to apply 
ferrites to the Metalux fixtures, probably not, but these lights will be on 
most of the nighttime hours so I do not want any noise from them.

The final test was a Utilitech T8 size LED fixture.  Upon initial testing I 
found no rise in the noise floor on any band except 20M which had a 5db 
increase in the noise floor into a 50 ohm resistor.  I didn't test this 
farther since after opening the product I determined that the LEDs were 
integrated into the fixture and not T8 style LED bulbs which would mean 
replacing the entire fixture if it failed.  There may be some other noise 
from this fixture and the Lithonia fixture (see next paragraph).

During the testing of these fixtures I noticed some in shack noise on the 
50 ohm resistor so I spent some time cleaning up a couple items in the 
shack which dropped the in-shack noise floor at least 10dB depending on the 
band, but had no impact on my noise floor with external antennas.  There is 
a chance the Utilitech and Lithonia fixtures may have some noise that I 
didn't initially detect.  As the experts say, clean your own house first.

I don't have the actual model/part numbers handy at the moment, but I can 
post them later.

I didn't check any replacement ballasts from Home Depot or Lowes, but I 
will say, even knowing what I was looking for, it was took a conscious 
effort to determine which were the proper residential ballasts.

I also checked some 40w and 60w Utilitech LED incandescent bulb 
replacements and have not noticed any noise floor increase in the 50 ohm 
resistor or with three of them in a fixture about 15' away.

>I also found the complete 4 ft 2-light fixtures made by Lithonia with the
>ballast made by Accupro (Model No. AP-RC-232IP-102-1) states it complies
>with 47 CFR Part 18 "consumer limits".
>On their spec sheets I found online
>[ http://www.lithonia.com/specsheets.aspx?cid=67054 ]
>%20ballast.pdf ]
>it states: "Ballast shall comply with the limits of FCC Part 18C Class B
>(residential) and Class A".  I've had these installed for years with no
>noticeable RFI even with my roof mount antenna only about 15-20 ft away from

73, Robert KR7O/YB2ARO, DM07ba/OI52ee  (ex.  N7STU)
DXCC  6M #1122
WAZ  6M #112
VUCC  6M, 2M

www.vhfdx.com (KR7O/YB2ARO pages)
Looking for old VHF QSL cards and logbooks.

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