Note: This is the text of the ARRL RFI pamphlet. It is strongly 
recommended that the original printed pamphlet be distributed
to the neighbor of a ham. Pamphlets are available from the ARRL
Technical Department Secretary, 225 Main St., Newington, CT 06111.
Include an SASE and a request for the RFI Pamphlet. A single stamp is 
good for about three of them. Clubs wishing quantities should contact Ed 
Hare at ARRL HQ (ehare@arrl.org).

Text follows:

What to do if you have an electronic interference problem

   This is a self-help pamphlet for the consumer published by the 
American Radio Relay League (ARRL). 
          
Introduction 

   As our lives become filled with more technology, the likelihood 
of unwanted electronic interference increases. Every lamp dimmer, 
hair dryer, garage-door opener, radio transmitter, microprocessor-
controlled appliance or remote-controlled new technical "toy" 
contributes to the electrical noise around us. Many of these 
devices also "listen" to that growing noise and may react 
unpredictably to their electronic neighbors. 
    
Interference: What Is It? 

   Complex electronic circuitry is found in many devices used in 
the home. This creates a vast interference potential that didn't 
exist in earlier, simpler decades. Your own consumer electronic 
equipment can be a source of interference, or can be susceptible 
to interference from a nearby noise source or radio transmitter. 

   The term "interference" should be defined without emotion. To 
some people, it implies action and intent. The statement, "You are 
interfering with my television" sounds like an outright 
accusation. It is better to define interference as any unwanted 
interaction between electronic systems -- period! No fault. No 
blame. It's just a condition. 

Personalities  

   You can't overestimate the importance of personal diplomacy 
when you're trying to solve a problem that involves two or more 
people! The way you and your neighbor behave when you first 
discuss the problem can set the tone for everything that follows. 
Everyone who is involved in an interference problem should 
remember that the best solutions are built on cooperation and 
trust. This is a view shared by electronic-equipment 
manufacturers, the FCC and the ARRL. 

Responsibilities  

   No amount of wishful thinking (or demands for the "other guy" 
to solve the problem) will result in a cure for interference. Each 
individual has a unique perspective on the situation -- and a 
different degree of understanding of the technical and personal 
issues involved. On the other hand, each person may have certain 
responsibilities toward the other, and should be prepared to 
address those responsibilities fairly. 

   The radio operator is responsible for the proper operation of 
the radio station. The station should be properly designed and 
installed. It should have a good ground and use a low-pass filter, 
if needed. If consumer electronic equipment at the station is not 
suffering the effects of interference, you can be almost certain 
that the problem does not involve the radio station or its 
operation. However, if the interference is caused by a problem at 
the station, the operator will eliminate the problem there. 

   Manufacturers of consumer electronics equipment are competing 
in a difficult marketplace. To stay competitive, most of them 
place a high priority on service and customer satisfaction. For 
example, many manufacturers have additional filters available for 
customers who live near sources of strong radio signals. Others 
have service information that can be sent to a qualified repair 
dealer. Most manufacturers are willing to resolve any interference 
problems that involve their products. Over recent years, 
manufacturers have built up a good track record designing 
equipment that functions well in most electrically noisy 
environments. 

   The FCC will do what it can to help consumers and radio 
operators resolve their interference problems. They expect 
everyone involved to cooperate fully. Experience has taught them 
that solutions imposed from the outside are not usually the best 
solutions to local problems. Instead, they provide regulatory 
supervision of radio operators and manufacturers. They also 
publish some self-help materials. These materials explain the 
several laws and FCC policies that relate to interference 
problems. 

   Finally, the consumer has responsibilities, too. You must 
cooperate with the manufacturer, the radio operator, and, if 
necessary, the FCC as they try to determine the cause of the 
problem. They need your help to find a solution. 

What Causes Interference?  

   Interference occurs when radio signals or electromagnetic 
"noise" sources are picked up by consumer electronic products -- 
most often telephones, audio equipment, VCRs or TVs. It usually 
results in noise, unwanted voices or distorted TV pictures. In 
most cases, the source is nearby. 

 There are three common types of interference: 

   1) Noise: Interference can be caused by an electromagnetic 
noise source. Defective neon signs, bug zappers, thermostats, 
electrical appliances, switches or computer systems are just a few 
of the possible sources of this type of interference. Both you and 
your neighbors may be suffering from its effects. In some cases, 
the noise may be the result of a dangerous arc in electrical 
wiring or equipment and may provide warning of an unsafe condition 
that should be immediately located and corrected. 

   2) Overload: Even if a radio signal is being transmitted on its 
assigned frequency, if it is strong your equipment may be unable 
to reject it. Your telephone, radio, stereo or TV should be able 
separate the desired signal or sound from a large number of radio 
signals and electrical noises. This is shown in Figure 1. 

   Consumer-equipment manufacturers have worked in cooperation 
with government regulators to set and meet voluntary standards of 
interference immunity. Modern equipment usually includes enough 
filtering and shielding to ensure proper performance under average 
conditions. Older equipment may not meet these standards, however, 
and even modern equipment can be affected if the interfering 
signal is particularly strong. In these cases, your equipment is 
working as designed, but it may need some additional filtering or 
shielding to function properly. 

   3) Spurious emissions: A nearby radio transmitter could be 
inadvertently transmitting weak signals on a frequency not 
assigned to that transmitter. These signals are called spurious 
emissions. FCC regulations concerning spurious emissions are very 
clear. If interference is caused by spurious emissions, the 
operator of the transmitter must take whatever steps are necessary 
to reduce the interference. Fortunately, modern transmitting  
equipment is manufactured to meet stringent regulations, and many 
radio operators are examined and licensed by the government. These 
federally licensed operators often have the technical skill to 
resolve interference problems that originate from their radio 
stations. 

Figure 1. Every electronic appliance must select only the desired signal 
while rejecting all others. 

   With all of these possibilities, it is difficult to guess which 
type of problem is causing your interference. Usually, only a 
technical investigation can pinpoint the cause and suggest a 
solution. This is where a spirit of cooperation and trust will pay 
off! If you believe your equipment is picking up signals from a 
nearby radio transmitter, the operator may be able to help you 
both find a solution to a mutual problem. 

How to Find Help  

   Most consumers do not have the technical knowledge to resolve 
an interference problem. Even so, it's a comfort to know that help 
is available. 

   Gather information about interference. The Electronic 
Industries Association (EIA), FCC and ARRL all have self-help 
information packages or books.

   If the problem involves an electrical-power, telephone or 
cable-television system, contact the appropriate utility company. 
They usually have trained personnel who can help you and your 
neighbor pinpoint the cause of the problem. 

   Consumer equipment manufacturers will also be able to help you. 
Your owner's manual, or a label on your equipment, may give you 
information about interference immunity or tell you who to call 
about interference problems. If not, the EIA will be able to give 
you the address of your equipment manufacturer's interference-
resolution personnel. The manufacturers know their equipment 
better than anyone else and will usually be able to help you. 

   Operators of licensed amateur or commercial transmitters 
usually have some technical ability. These operators are the 
nearest source of help. Remember, the station operator may also be 
a neighbor! Use a polite approach to ensure that the relationship 
stays "neighborly." Licensed Amateur Radio operators have access 
to volunteers (Technical Coordinators and local interference 
committees) who are skilled at finding solutions for most 
interference problems. 

Testing one, two, three . . .  

   If you think a neighbor's radio transmitter might be involved, 
you and your neighbor should arrange a test. It's important to 
determine whether the interference is (or is not) present when the 
radio station is "on the air." Your neighbor may want to ask 
another operator friend to participate in the test at your home. 
By the same token, you may want to invite a friend to attend the 
test at the radio operator's station. Having impartial witnesses 
will make you and your neighbor more comfortable with the outcome 
-- whatever it may be. Be sure to choose your witness carefully. 
Select someone who is diplomatic and tactful. 

   The tests must be thorough. The transmitter operator must try 
all normally used frequencies, antenna directions and power 
levels. All results must be carefully written down. More than one 
set of tests may be needed. Once you and your neighbor have 
determined which frequencies and power levels cause the problem, 
you'll be one step closer to finding a solution. 

Self-help Cures  

   In some cases, when all else fails, you may need to resolve the 
problem yourself, or with the help of your electronic service 
person. It's impossible to use the remaining space to outline all 
of the possible cures for interference problems (the subject is 
quite complex.) However, a few simple cures using commonly 
available parts can eliminate most problems. The self-help 
packages supplied by the EIA, the ARRL and the FCC explain these 
cures in more detail. 

Try the Easy Things First  

   Sometimes, the easiest solutions are the best. Many cases of 
interference can be resolved without the need for technical 
investigations or knowledge. 

   If you suspect that the problem is caused by electrical noise, 
check for overloaded circuits, frayed wires, loose sockets, etc. 
These types of problems should be fixed no matter what! Have your 
electrician shut off one breaker at a time, noting if this has any 
effect on the interference. If so, determine which devices are 
connected to that particular line, then remove the suspect devices 
one at a time. When the interference goes away, you've found the 
"culprit." Your electric-utility company service department will 
offer assistance if the interference is coming from defective 
equipment on the power lines or distribution equipment. 

   Interference filters for your consumer equipment can be 
purchased locally or by mail order. These filters usually 
eliminate unwanted interference if they are used properly on the 
equipment that is in need of additional filtering. 

   According to the FCC Interference Handbook, telephones and 
other audio devices that pick up radio signals are improperly 
acting as radio receivers. The interference can usually be cured, 
but the necessary filtering must be applied to the affected 
device. 

   Several companies sell modular telephone interference filters 
that are very effective. Your telephone company service department 
may be able to help.

   A high-pass filter may help reduce interference to an antenna-
connected television receiver or VCR. A common-mode filter should 
be tried first on TVs or VCRs connected to a cable system. An ac-
line interference filter may also help with electrical or radio 
interference. These items may be available from the consumer-
equipment manufacturer. They also can be purchased locally or by 
mail order.

   Some interference cures must be applied to the internal 
circuitry of the affected equipment. This should always be done by 
authorized service personnel. 

   The ARRL has a free information package called RFI Tips." They 
also sell a book, Radio Frequency Interference - How to Find It 
and Fix It, that provides additional guidance and technical 
information. Although it was written for amateur operators, the 
book may be helpful to you, too. Contact ARRL for information 
about their products and membership services. 

Interference Can Be Cured!  

   Remember, most cases of interference can be cured! It takes 
cooperation between the consumer, the manufacturer and the radio 
operator. With a little bit of work you and your neighbor both 
enjoy your favorite activities in peace. 

For More Information . . .  

   The EIA, the ARRL and the FCC all have self-help packages 
available to help you resolve interference problems. There is no 
charge for these materials. 

Addresses:  

American Radio Relay League, Inc. 
RFI Desk 
225 Main St. 
Newington, CT 06111 tel (203) 666-1541 

Electronic Industries Association 
Executive Director of Consumer Affairs 
2001 Pennsylvania Ave NW 
Washington, DC 20006 
tel (202) 457-4977 

Federal Communications Commission 
Washington, DC 20554 

Sources of Products: 

High-pass filters: 

Radio Shack
Catalog: 15-579 75-ohm 
Catalog: 15-582 300-ohm 

Common-mode filters

TCE Labs
2365 Waterfront Park Drive
Canyon Lake, TX  78133
(210) 899-4575, (800) KILL-TVI

Telephone interference filters: 

K-Com
POB 83
Randolph, OH 44265
tel (216) 325-2110

TCE Labs
2365 Waterfront Park Drive
Canyon Lake, TX  78133
(210) 899-4575, (800) KILL-TVI
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