Wednesday 6 January 2016

LED Lights In The Shack

Utilitech Pro Soft White LED Bulb

A recent posting by Phil, KO6BB, to Yahoo Group's ndblist, described his recent search for some LED lamps to replace the CFL's in his shack / radio workbench area. If you have been wondering how much RFI that LED lamps might be producing, you may find Phil's findings of some value.


I had a 60W equivalent CFL in the floor lamp directly over my operating position. I'd tried a 100W equiv one but it was extremely noisy! Also a couple CFLs in the ceiling lamp.

This is a floor lamp with a crookneck at the top and a triangular metal
shade reminiscent of the old style desk lamps, bulb is horiz to the
floor. I've used it for years and like it because it places the light
directly over the operating position work area (keyboard, radios etc).
The actual bulb was about 4.5 inches from the front of the Softrock SDR
receiver (in a plastic case), with the base of the lamp (where the
electronics are) about 7.5 inches (somebody asked about the distances).

This coupled a LOT of RFI directly into the SDR, visible on the
waterfall. For best results when recording and having the light on I'd
slip a 60W incandescent lamp in place of the CFL. The lamp is also
about 16 inches above the operating table, and when listening to ANY
portable radio on the table, if it was in the AM or Longwave band and
using the built in loopstick antenna, got a LOT of RFI from the lamp
(unless the lamp was off ;-)

So today I went down to Lowes (we have a Costco, but I don't have a
card) and looked at their LED lamp offerings. As I expected they had a
large variety of them, from a low cost 3 pack for ~$9.00 for 60W units
to about $18.00 or so each (Sylvania). From what I read here I wanted
to avoid the REALLY cheap ones as some reported them to be 'noisy'.
Also, I wanted to put a 75W equivalent unit in the one over the
operating position, and a pair of 100W equivalent units in the ceiling
lamp. All three had CFLs, and if I walked around the radio room with a
portable radio and the ceiling lamp on I could hear it's 'hash' anywhere
in the room. . .

The ones I settled on were a brand I'd never heard of, "UtiliTech Pro"
soft white, 75W for the bench and 2 100W ones for the ceiling. They
were what I'd call "mid-priced", $8.98 for the 75W and $9.98 for the
100W ones.


75 W one draws 12W and gives 1100 Lumens.
100W one draws 16.5W and gives 1600 Lumens (the pair in the ceiling
should then be 3200 Lumens if I calculated right).

How low is the RFI to my Radios?

75W one over the bench:
NO trace from the lamp electronics visible in the SDR waterfall at
all. With a portable radio on the bench-top, NO audible RFI. Put a
portable radio up to the "bulb" part (light area) and with no station
tuned in can't hear ANY RFI. Move the portable to the base area of the
lamps there is SOME RFI, but I won't be putting the radio that close to
the lamp, move it a couple inches away and the noise disappears.

100W ones in the ceiling lamp, NO audible RFI in the portable when
walking around the room, RFI just barely perceptible right next to the
light wall switch that turns the lamp on, again, audible IF I put the
radio right up to the base of the lamps, not a likely real-world scenario!


Based on the sample of three that I bought and the almost
non-existent RFI from them I'd consider the UtiliTech Pro lamps to be a
good product and suitable for use in the radio room. I consider them
good value for the ~$30.00 I spent for three."

I don't see these being sold here in Canada but I may be mistaken. If you have tested anything similar (other brands / models), please let me know and I will add it to Phil's helpful information.

KO6BB's website can be found here, along with some of his homebrew equipment.


Anonymous said...

Steve -- I found an LED bulb caused significant interference from AF to UHF on a lab test bench. Scroll down in my AF building part 2 Section D

Steve McDonald said...

I'm sure there are some bad ones out there you recall what brand it was? It would be nice to document the bad ones.


Anonymous said...

Steve - you & I have discussed this on air: my whole house is now full of LED light bulbs & I continue to replace incandesants whenever possible. These are 9 watt, 9.5 watt, 12 watt + some 16w spotlight bulbs. I have a mix of different brands throughout the house. I have one of these in the desk 'gooseneck' lamp hovering over my radio shack, including my Quantum QX Pro Loop 3.0. There are NO interference problems whatsoever. I'm sure one can buy a "bad" bulb & it will be easy to determine with my portable Sony tuned down to 100 kHz for a walk through the house to find the offending bulb. So far no problems. CFL's should be banned - they emit horrid RF, are an environmental nightmare containing mercury & god-know-what. If they break on the floor, you need a HAZMAT team to clean it up! :-(


Steve McDonald said...

Good info there Mike ... thanks! Do you know what brand your lights are?


Vasily Ivanenko said...

Hi Steve and crew.

The 2 LED bulbs tested = OSRAM Sylvania 9.5W. I’m not 1 to easily fall prey to the illusion of causality, and don’t suggest that all LED bulbs cause RFI, however, in my case, 2 LED bulbs did.

My controls were 2 different CFC bulbs [ 1 unknown, the other an OTTLite 15W bulb – see note below ]. While both CFC bulbs emitted predictable 60 cycle noise, that’s easily bypassed -- and no RFI was measured in circuits under test on my bench – even when measuring noise.

My point = you need to measure to know.

On my bench lit with a desk lamp containing either of the 2 Sylvania LED bulbs mentioned, measures with a spectrum analyzer ( I can go down to a 10 Hz resolution BW) and 2 DSO’s showed RFI from AF to UHF.

It’s possible that 120 Hz luminosity ripple plus harmonics from mixing inside those bulbs was in play. Inside LED bulbs filtering and perhaps even shielding might vary across the manufacturers.

In the end, I went back to my standard all OttLite bulb solution – they run a color temp of 5000 deg K. The advantage of this bulb over others, apart from not shedding RFI, is that the color temp is close to my camera flashes and I get perfect white balance in my bench photographs.

Also the OTT light contrast proves excellent for SMT work for this older goat. I’ve got 3 higher mounted lamps with wide angle diffusers, plus the 1 desk lamp added for more specular lighting to boost contrast in my circuit boards.

1 visiting EE recently remarked that my bench looks like a photography studio.


Steve McDonald said...

Thank you Todd. I'm still holding out with my old tungsten bulbs...bought several dozen a few years ago. Maybe Mike will tell us what brand of quiet LED bulbs he uses.

Anonymous said...

Steve - I grab whatever comes up on sale & so far haven't paid any attention to sticking with certain brands - here in the house: Sylvania, Phillips, Home Hardware, Electr-VLART. I'm sure some day I'll end up with a bad one & will trace it & replace it. However, I doubt I can return a functioning LED bulb that emits RFI to the dealer for a refund if I end up having to remove one! :-)

73 Mike VE7SKA

Anonymous said...

addendum = 1/16/2016

My wife just bought a new LG LED huge-screen TV. I got it all set up & then nervously retreated to the ham shack, plugged in headphones & fired up my trusty Icom R75 receiver. I tuned all the way through the MW band & LW down to 100 kHz. NO interference or RFI whatsoever!!!! Next, a tune through the HF spectrum & no changes noticeable.

with a huge sigh of relief...


Steve McDonald said...

Thanks for your info Mike. Like you, I always hold my breath when plugging-in a new toy / appliance for the house. From my own experience, the LED TV's are darn quiet (Samsung) ... it's the plasma ones that are nasty ... I wonder if these are being phased out at all?


f6hcc said...


Some test on:

(sri in french but a few video with audio...)

John / F6HCC