December 1953 QST
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
QST, published December 1915 - present (visit ARRL
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According to this 1976 issue of
QST magazine, in 1974 the FCC received 42,000 complaints of radio frequency
interference (RFI). 38,000 of them (90%) involved interference to
home-entertainment devices such as stereos and TV sets. 34,000 (89%) of were
found to be due to design deficiencies in the home-electronic devices
themselves. Since that time, and especially since Wi-Fi and cellphones, the
potential for RFI has increased significantly. Fortunately, thanks to much more
stringent compliance testing, the likelihood of interference from a commercially
produced device has been reduced, but the sheer volume of stuff spewing some
level of RF energy has raised the overall noise floor in heavily populated
regions around the world. Concurrently - and also fortunately - technology
advances in filtering, oscillator frequency stability, shielding, and modulation
schemes allow lower transmit power levels for equivalent reception range, thus
minimizing ambient RF energy. A huge commercial market for wireless devices has
driven costs down so that manufacturers are able to add more noise emission and
immunity margin into their products. Still a lot of products flowing into the
country violate FCC standards and manage to distribute them throughout the land
before being caught. We have seen that happen a number of times in the radio
controlled drone, amateur radio, and knock-off consumer electronics markets.
RFI Grows Up
RFI - Once only a problem child; now a juvenile delinquent; soon to be a hardened
By Hal Steinman,* K1FHN
What is this creature called RFI? Why does it suddenly seem to be receiving so
much attention in amateur radio magazines? Why, in this session of Congress, are
there two bills concerning it? Who is at fault when RFI occurs? Where can an amateur
go for guidance when he is confronted with a tough RFI case? Is the future of amateur
radio in danger because of the proliferation of RFI? Is it really worth all the
attention it's been getting?
What Is It?
For newcomers to amateur radio we should state that RFI stands for radio frequency
interference. It occurs; rather, it has the potential to occur, whenever an electronic
device finds itself surrounded by a field of radio frequency (rf) energy. The origin
of the rf energy could be an amateur, citizens band, fire, police, commercial, am, fm, or TV transmitter. The electronic device subjected to the rf energy could be
a television set, phonograph, fm radio, medical equipment or even an electronic
anti-skidding device on board a truck or bus. RFI actually occurs when the electronic
device in the midst of the rf field behaves or responds in an undesirable manner
because of the presence of the rf field. Sometimes the transmitter is at fault -
if harmonics or parasitic oscillations are not sufficiently suppressed. But more
often than not, as FCC statistics show, the fault lies with the electronic device
itself, due to insufficient filtering or shielding.
How Bad Is It?
In fiscal 1974 the FCC received 42,000 complaints of radio frequency interference.
38,000 of these involved interference to home-entertainment devices such as stereos
and TV sets. 34,000, or 89 percent, of these complaints were found to be due to
design deficiencies in the home-electronic devices themselves. That is to say that
an amateur or CBer operating a "clean" station on authorized frequencies completely
within the law could do absolutely nothing to his station that would prevent the
RFI from occurring. In fiscal 1975 the FCC received 55,289 radio frequency interference
complaints of all types, 45,002 of which involved home-entertainment equipment.
Eighty-two percent, or 36,900, of these were found to be the fault of the entertainment
equipment. We emphasize that this means 36,900 cases of RFI occurred regardless
of any measures that could have been taken at the transmitting station itself. Late
word at this writing is that FCC received 80,768 RFI complaints during fiscal 1976.
This represents almost a 50-percent increase in one year!
... it is the home-entertainment device itself that is to blame in well over
80 percent of the cases of RFI.
Another way of looking a t these FCC statistics is that well over 80 percent
of RFI complaints concerning home-entertainment devices would never have occurred
at all if the manufacturer had included proper filtering or shielding in his unit!
Why this rapid growth in RFI complaints? One reason is the substitution of solid-state
devices for vacuum tubes in home-entertainment equipment. Solid-state components
are less expensive, run cooler, have longer lifetimes and are easier to service
when built in modular form. At the same time they are more susceptible to rf radiation.
Another reason for the upsurge in RFI complaints is the simple fact that the probability
of a home-entertainment device being located near a transmitter of some sort has
increased markedly in recent years. The citizens-band explosion has contributed
to this in no small way. Over 500,000 new licenses are being issued monthly in the
Citizens Radio Service. Many of these transmitters are in homes or automobiles and
in very close proximity to television sets, broadcast receivers and audio equipment
used for home entertainment. Manufacturers used to say that only 1 percent of the
population would ever be located close enough to a transmitter to experience interference.
This is no longer the case. FCC now predicts that the probability of a home-entertainment
device being located within a significant rf field, particularly in metropolitan
areas, is in the neighborhood of 50 to 70 percent.
Bad News for Amateurs
This tremendous increase in RFI complaints indicates that a problem exists, and
that problem is coming to light. The more complaints, the more likely that action
will be taken to solve the problem. What is wrong, though, is that most consumers
tend to automatically put the blame for the interference on the operator of the
station whose signal is being intercepted, and as we have seen, it- is the home-entertainment
device itself that is to blame in well over 80 percent of the cases of RFI. Moreover,
regardless of what type of signal is being intercepted - amateur, CB, fire, police,
commercial a-m, fm, or TV - the complainant is likely to believe he is being interfered
with by a "ham" operator, even though in fiscal 1976 80 percent of the complaints
of interference to home-entertainment devices involved citizens-band stations, and
only 7 percent involved amateur stations. Although there is more public awareness
now than there was only a few years ago, most of the population is still confused
by the distinction between amateur and CB radio. Moreover, when a consumer's expensive
TV set or stereo is experiencing RFI, he is probably not interested at all in whether
the station he is hearing is an amateur or a CB station. He simply wants the interference
to stop. To sum it up, the fault is probably in the home-entertainment device itself;
the station being intercepted is probably not an amateur station; and in all probability
amateur radio gets the blame. It's a no-win situation, and the image of amateur
The first RFI bill was introduced in the 92nd Congress in 1972, and again in
the 93rd Congress in 1973, by the late Charles M. Teague, Congressman from the 13th
District of California. The bill was never enacted into law, but it set a precedent,
and again in the 94th Congress RFI legislation was introduced. In May of 1975 HR-7052
was introduced in the House of Representatives by the Honorable Charles A. Vanik
of Ohio. In February of 1976 Senator Barry Goldwater introduced a similar bill,
S-3033, in the Senate with these words: "Mr. President, I am pleased to introduce
today a companion bill to legislation proposed by Congressman Charles Vanik of Ohio
to drastically reduce the amateur and CB radio bugaboos of television interference,
hi-fi interference, and other radio frequency interference to home-electronics equipment.
... at present the FCC has no power to set standards for the susceptibility of
home-entertainment devices to rf energy.
"Most consumers do not understand that when they may encounter interference with
their home television or radio set after an amateur or citizens band radio operator
moves next door, the source is not a defect in the equipment of their neighbor but
with their own radio or television ... " (Congressional Record - Senate - February
These bills are necessary because at present the FCC has no power to set standards
for the susceptibility of home-entertainment devices to rf energy. This is sort
of a "loophole" in the Communications Act of 1934 that the FCC wants to plug. Manufacturers
of home-entertainment devices, in a competitive market place, are reluctant to take
the initiative to RFI-proof their equipment. It is true that factory installed RFI
protection would raise the price of a typical unit - estimates vary from a few cents
to perhaps as much as five dollars. There is no incentive for one manufacturer to
install additional filtering or shielding if it would put him at a competitive disadvantage
in the market place. But, if the law required it, no particular manufacturer would
be put at a disadvantage. Others argue that these bills are anti-consumer since
they would raise the price of entertainment equipment for everybody. But this argument
is fallacious since the purpose of the bills is to improve defective equipment and
it is far cheaper for a manufacturer to RFI-proof a piece of equipment at the time
of manufacture rather than on a case-by-case basis.
What's to Worry About?
We've stated that well over 80 percent of the reported cases of interference
to home-entertainment devices is the fault of the entertainment equipment itself.
We've also stated that in fiscal 1976 only 7 percent of these complaints involved
An amateur ... who is put off the air under such a law could undoubtedly have
the ruling overturned - but not without costly litigation.
Taking these facts out of context one would be tempted to conclude that amateur
radio has little to worry about. Nothing could be further from the truth. We've
seen that in many cases of such interference it is amateur radio that suffers. More
public education on the distinction between amateur and CB radio is needed, but
this does not address the real RFI issue - that the entertainment device needs corrective
measures, not the transmitter. An amateur cannot rest easy after he convinces his
neighbor that the strange voice coming over his TV set is that of a CBer, not an
amateur. Perhaps he will even explain to his neighbor the difference between the
amateur and CB services. Perhaps he will even, on his own initiative, help his neighbor
clear up the interference, thereby earning his gratitude and gaining a supporter
for amateur radio. We applaud these actions. It is much more constructive to solve
a problem in a positive manner, even if one is not at fault, than to put the blame
on someone else and be done with it. But can the amateur rest easy even after doing
all these things? The answer is still no, for we are being attacked on a wider front.
According to Ted Cohen, W4UMF, secretary of the ARRL RFI Task Group, there are already
47 states in which at least one municipality has a law on the books under which
an amateur radio operator can be cited for causing interference. These laws generally
are of the "causing a public nuisance" variety. Such laws ignore, the fact that
the "cause" of the interference probably rests with the entertainment device itself.
Such laws, if appealed, would no doubt be ruled invalid, as concerns RFI, since
the Communications Act of 1934 reserves the regulation of transmitters to the federal
government. But, sorrowfully, these laws are often put on the books with little
publicity before anyone realizes what is happening or recognizes their implications.
An amateur or CBer, operating a clean station and within the law, who is put off
the air under such a law could undoubtedly have the ruling overturned - but not
without costly litigation. So we see that amateur radio does have a great deal to
The point has been made that the crux of the RFI problem is that far more often
than not the corrective measures must take place at the entertainment device. The
proposed consumer legislation in Congress will help toward this end. But more immediate
is the problem of consumer education. Whether you realize it or not, the fact that
a TV set or stereo can be the "cause" of interference is a very difficult concept
to comprehend. We, as amateurs, understand it because we are familiar with the problem.
But to others it defies all logic. How can an apparently "passive" device such as
a TV or stereo be a "source" of interference when obviously there is a transmitter
out there somewhere that is spewing out rf energy very "actively," and that rf energy
is entering one's home, uninvited, and interfering with a home-entertainment device
that is just sitting there innocently? Expressed in these terms this, might strike
you as facetious, but it is not intended to be. This difficult-to-comprehend concept
is the reason that a consumer's first impulse is to blame the "ham" down the block.
It is also the reason that municipalities pass protection-against-interference laws
that put the blame on the transmitter, thereby attacking the symptom but not the
cause. But how do you explain to an irate neighbor that his $500 TV has a built-in
defect? How do you explain to a zoning board that is about to prohibit the owner
of one lot from causing interference to the owner of another lot that it is preempting
the authority of the federal government? How do you write a letter to a newspaper
to undo the harm which a previous letter or article has done? The League's RFI packet
contains some hints, including a sample letter-to-the-editor. This author has encountered
a particularly neat analogy that is useful in explaining to a person not versed
in electronics how a "passive" entertainment device can be the cause of an interference
problem. J. W. Swinnerton, G2YS, writes in the journal of the Radio Society of Great
Britain, Radio Communication, "You point out that his equipment is receiving signals
it should be proof against - and if it is only an audio amplifier it should not
be receiving them anyway. It is acting like an ill-fitting door letting in the draught
- the cure is not to try to halt the wind but to improve the door."
... how do you explain to an irate neighbor that his $500 TV has a built-in defect?
... the fact that a TV or stereo can be the "cause" of interference is a very
difficult concept to comprehend.
What to Do
It has been the purpose of this article to explore some of the history, causes
and implications of the RFI problem. A book would be required to discuss in depth
all ramifications of RFI, and, of course, this article did not deal at all with
the technical aspects of RFI. But no article would be complete if it did not offer
some concrete and constructive steps that one could take to do his share to solve
the RFI problem. We recommend the following:
1) Send for the League's RFI packet. It contains, in part, suggestions on how
to organize local interference committees, sample letters-to-the-editor, reprints
of Congressional RFI bills; a list of people to write to within certain companies
for assistance in solving RFT complaints, a sample letter written to the manufacturer
of a home-entertainment device experiencing radio frequency interference, a reprint
of an article from Radio-Electronics called "Audio Signals You Never Bargained For,"
a copy of the FCC Statement to Television Receiver Owner, and a copy of FCC Field
Engineering Bulletin No. 25: Audio Devices - Interception of Radio Signals. The
packet may be obtained free of charge by writing ARRL, Newington, CT 06111.
2) Write your Congressman and Senator to express support for bills HR-7052 and
S-3033 and similar bills to be introduced in Congress in 1977. Tell them in your
own words that almost all RFI complaints related to home-entertainment devices would
disappear if this legislation were enacted.
3) Write the manufacturers of home-entertainment devices which you or your neighbor
are considering buying to express your displeasure that their equipment may be susceptible
to RFI. If you are personally involved in an RFI case, even if you've solved it
yourself, write the manufacturer and let him know if he was at fault. A list of
addresses of manufacturers to write to is contained in the RFI packet.
4) Solve your local RFI problems quickly, pleasantly, and amicably. Some manufacturers
assist by supplying at no charge kits, parts and appropriate instructions. Have
the RFI packet on hand to help you. Present amateur radio in the best possible light.
Solve your local RFI problems quickly, pleasantly, and amicably. Have the RFI
packet on hand to help you.
5) Be ever alert to possible legislation or administrative rulings that could
adversely affect amateur radio. If you find out that your local city council or
zoning board is considering a protection-against-interference ordinance let Hq.
know about it immediately. Otherwise, we may never find out about it until it is
too late. Hq. will rush material to aid in the fight against such ordinances.
Think about this: If each League member wrote his representatives in Congress
as suggested above, over 120,000 letters would be written to each of the parties
involved. But 120,000 letters will be written only if each and everyone of us cares
about the future of amateur radio. Do you care?
[Editor's Note: The author wishes to thank Ted Cohen, secretary of the ARRL RFI
Task Group, whose "Interference" column, which appears monthly in Worldradio News,
was a source of much of the, background material for this article.]
* Assistant Secretary, ARRL
Posted September 28, 2020