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Latest Topics

Topic Created Posts Views Last Activity
ARRL News Hotline Jun 17th 2014, 00:09 1 762 on 17/6/14
E&M Modeling Software? Jan 1st 2012, 05:36 2 1,478 on 1/1/12
Xcvr Repairs? Jan 1st 2012, 05:05 4 2,074 on 6/2/12
Broad Band Interference Jan 1st 2012, 03:51 14 2,717 on 14/2/12
Kenwood TR-751A Memory? Dec 17th 2011, 05:37 3 2,168 on 20/12/11
Wideband RFI Bursts - Please Help! Nov 20th 2011, 21:49 11 2,739 on 11/5/12

Latest Posts

Topic Author Posted On
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.
Wideband RFI Bursts - Please Help! AC0XU on 16/4/12
After many phone calls and emails, Comcast did send a team out to the neighbor's house. Apparently, they re-wired the cable system in the house. That was nice of them.

Unfortunately, that is not the end of the story. While the neighborhood cable system in general appears to be less of an RFI emitter now, the neighbor's house is still transmitting powerful signals. It seems that Comcast was able to decouple their system somewhat from whatever in that house is producing the RFI, but the over-the-air RFI is pretty much unchanged. The level of the RFI is 20 to 30 dB above the general noise floor on 20m, and it persists, albeit at lower levels, in the 40m and even the 75m bands as well.

I have tried active noise cancellation. Unfortunately, those systems apparently don't do much for bursty noise.
Broad Band Interference AC0XU on 5/2/12
Why would a doorbell transformer generate a regular burst at regular 1.3 second intervals 24x7? Thanks for the suggestion. If the neighbors ever let me back in their house I will check their doorbell system.

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