[OFARC] finding RFI sources

[Ralph (home)]

I am battling RFI at my home QTH right now and am working with CenterPoint
to resolve some of the problem.

We found a bad variable speed ceiling fan switch in my home generating about
1.5S units of noise.

But about 5S units are coming from my back neighbor.

 

I thought it would be good to share the "art of RFI hunting" with the club
again.

 

73

Ralph, KE5HDF

 

 

There are some key steps a radio operator needs to take before calling in
the specialists on RFI.

First.  characterize the noise 

*       Keep records of date and time, including weather conditions (a week
or 2 should be enough)

*       Damp weather can aggravate noise from power line components

*       Does it change with time of day

 

Second.make sure it is not in your radio

*       disconnect all antennas and see if the noise changes

*       if the noise gets less, it is likely NOT in your radio

*       if the noise does not drop, disconnect from the power supply and run
on battery with no antenna

*       if the noise drops, it is the power supply

*       If the noise remains, it is your radio . get it serviced.

 

Next look for noise sources in your home.

IT MAY BE MORE THAN ONE DEVICE CAUSING PROBLEMS

Do not stop when you find your 1st problem.

 

Try the following steps to see if any cause the noise to decrease

*	turn off/unplug PC
*	disconnect radio from power supply and run on battery
*	shut off power to refrigerator (not a common problem)
*	shut off power to my freezer (not a common problem)
*	unplug fluorescent light near shack (common!)
*	unplug any battery chargers near the shack (common!)
*	unplug small power supplies (common!)
*	unplug plasma screen TV (common!)
*	shut off all power to home; run on battery

If none of the above makes the noise decrease, you have a problem outside
your home

Contact CenterPoint Senior  Radio Technician .. Jeff Hoke
jeff.hoke at centerpointenergy.com <mailto:jeff.hoke at centerpointenergy.com> 

*       If it is line noise, he will fix it or create a work order to repair

*       If it is in a neighbor's home, he will try to identify the part of
the house that is causing problems

*       Try to contact your neighbor and explain the safety issues of bad
electronics (can cause fires, can interfere with emergency radio comms.)

*       As a licensed radio service we are legally protected from many kinds
of interference, but prefer to solve issues as good neighbors

*       If they are agreeable, help them find the problem device

*       It is probably best to have them contact a repair service so you
cannot be blamed for problems with the device later.

*       If they are not agreeable, contact ARRL, explain what has been done,
what was found, and seek advice.

*  ARRL  may suggest relaying directly to FCC, or they may send a letter on
your behalf and explain legal requirements

If any of them cause the noise to decrease, you have some noise generated in
your home.

If unplugging items in the shack does not help, but the noise decreases when
you shut off power to your entire house, then take these steps

*       Try using a portable receiver in AM mode, without an antenna

*       Hold it next to each outlet or device

*       It will have a lot of "hash" when next to a problem device

*       You should be able to isolate the room or maybe even the device this
way

If no luck, then try this method

*       turn breakers off one at a time

*       watch the noise level closely

*       when the noise returns (or gets worse) the problem is on that
circuit

*       turn on the problem breaker

*       go to the room(s) supplied by that breaker

*       unplug each item one at a time (simply turning it off may not cut
power to the entire device)

*       when the noise drops, you found the problem

*       NOTE .. It could be a bad switch, GFCI breaker or GFCI outlet

Possible ways to fix RFI in your home

*       make a choke of 3-6 coils in the power cord and tape it to stay
tight

*       add 1-3 ferrite beads over the power cord

*       replace bad switches or breakers

*       replace the lamp

*       change "curly bulbs" to incandescent bulbs

*       change early generation LED bulbs for new version

*       change LED bulbs for incandescent bulb

if it is a major appliance and none of the above helps .. Call the
manufacturer.

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