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Latest Topics

Topic Created Posts Views Last Activity
RFI and Residential Marijuana Grow Operations Jul 4th, 15:26 2 166 on 4/8/16
ARRL News Hotline Jun 17th 2014, 00:09 1 813 on 17/6/14
E&M Modeling Software? Jan 1st 2012, 05:36 2 1,534 on 1/1/12
Xcvr Repairs? Jan 1st 2012, 05:05 4 2,137 on 6/2/12
Broad Band Interference Jan 1st 2012, 03:51 14 2,854 on 14/2/12
Kenwood TR-751A Memory? Dec 17th 2011, 05:37 3 2,232 on 20/12/11
Wideband RFI Bursts - Please Help! Nov 20th 2011, 21:49 11 2,860 on 11/5/12

Latest Posts

Topic Author Posted On
LED light bulbs cause RFI W7DRM on 4/7/16
I have found that CFL bulbs are almost universally worse than the LED bulbs, so I have replaced all the CFLs around my house with LEDs. Sounds like bad luck there with your purchasing choice. I have had good luck with Cree LED bulbs, which Home Depot sells in my neighborhood. You also might want to try Philips bulbs - I don't have RFI data on their products but in my experience Philips makes what are probably the world's highest quality light bulbs in general, so we might conclude that they engineer their products better than other manufacturers.
RFI and Residential Marijuana Grow Operations AC0XU on 4/7/16
Various other neighborhood RFI problems have come and gone. My neighbors have not been cooperative. Cable boxes have been one culprit. Others, I don't know, but after a year or more most RFI sources just go silent. It has been worrisome that Solar City installations have been going in but so far they seem to be reasonably quiet, at least compared to the following problem.

The latest RFI source which wipes out all HF operation during the day is the marijuana grow operation 2 houses away. I first found out about this when the power kept going off. The electricity linesman told me that house consumes about 10x the normal residential draw. Add to that the blacked out windows, dogs and security systems... A portal radio with a loop and a 360 degree walk around the house makes it clear where the RFI is coming from. Excel Energy installed a larger transformer, which solves the outage problem, but does not eliminate the RFI!

This is a clear zoning violation but the city won't do anything. The police have been monitoring the situation but they say they can't shut down the grow operation until they have sufficient evidence. Considering the nature of the business, I am reluctant to confront the residents.

The grow lights raise the general noise level over all the HF bands around 10 dB. With directional antennas, including several loops and a hex-beam, I can occasionally copy a few signals that come from orthogonal directions. Anything within 45 degrees of the direction to the neighbor's house is nearly impossible.


Mystery signals 53.335kHz harmonics K3KXJ on 17/6/14
This is typical of noisy switching power supplies. The signal gets into house wiring, plumbing, coax, etc and can be difficult to DF. Power off everything at the main breaker in your house. Run your radio by battery - if you are still seeing the RFI then it is not coming from your house equipment. If the RFI goes away, turn on the breakers one by one until you track down the culprit.

I have seen this kind of RFI from cable modems, satellite TV equipment, and other folks have reported it from lighting systems, electric blankets, fence chargers, and wall warts.
T8 Lamps W1MG on 17/6/14
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.

ARRL News Hotline AC0XU on 17/6/14
Last night I heard the ARRLs new hotline on grow lamps and RFI. The ARRL suggests that AROs not try to contact owners but file reports with the FCC.

If it were April 1 I would assume that was a joke. Or maybe the FCC has a bigger presence on the east coast. I have spoken with Denver FCC field office. As I recall, they told me they have 3 field investigators to cover a 5 state area. If you are an emergency services provider, a broadcaster or a cell operator, maybe the FCC will investigate your RFI problems. I have identified the sources of my RFI problems, all from local homeowners and the city of my residence, and I have not been able to get the problems fixed. I find my neighbors mixed as to cooperativeness, but they seem to think that it I am a nuisance. The City of Aurora is not interested.

I have found my Trane furnace and my Champion garage door opener to be huge sources of RFI. I have fixed those problems (thanks to other hams for info about the terrible Trane variable speed induction motors). I contacted both manufacturers - they did not want to hear about the RFI. I also had RFI problems from my SGC antenna tuner - but SGC did not want to hear about the problem nor would they even fix the problem under warranty. I filed reports with the FCC multiple times. I have also removed all noisy lights from my premises - and all the CFLs I have tested are noisy as heck.

Regarding the recent concerns about RFI from grow lights - I posted a complaint about a specific product on Amazon. All I have received as a result is abuse from people with alleged "questions" about the product. One guy said that he was going to make a point of creating all the ham radio interference he possibly could.

It feels like it is a battle to keep HF communications viable in my metro area. I understand why many hams have given up and only do VHF and higher.

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