This is a very interesting article about the
FCC's "Secrecy of Communications" rules. Manmade radio interference (QRM in Ham
lingo), has been a problem since the early days of wireless communications. You
might convincingly argue that it was worse at a time when many transmitters were
of the arc type that basically spewed out a mess of RF energy within a specified
bandwidth (very wide compared to today) to signal the presence of a "dit" (a digital
"1"), with the absence of a signal being a "dah" (digital "0"). Filter technology
for both the transmit and receive sides was also poor, allowing unintentional RF
noise to be sent over the air and to find its way into the detector circuits. The
Communications Commission (FCC), first formed in 1934, nearly four decades after
Guglielmo Marconi first demonstrated his wireless set in 1896. Sometime around
1952, the FCC allocated a half dozen frequencies in the 27 MHz for radio control
(R/C) model use, mixed within the existing citizens band (CB) radio channels. As
you might imagine, interference problems were rampant, especially near metro areas
and highways with heavy truck traffic. This editorial in a 1969 issue of American
Aircraft Modeler magazine reports on just how bad things had gotten, especially
that caused by operators using faulty and/or illegally modified transmitters, and
even by malicious intentional attempts to "shoot down" model airplanes by keying
transmitters in the vicinity of flight activity. In 1965, the FCC allocated a
dedicated band of frequencies at 72 MHz for use by radio control aircraft
(a separate band at 75 MHz was made available for land craft). My first R/C
system was a 3-channel
OS Digitron unit at 27.195 MHz (purchased second-hand around 1974, at 14
years old), and I definitely recall interference with it. Watching your airplane
that you spend precious dollars and time on (not pre-built like most of today's
models) go crazy and out of control - even for a few seconds - was hair-raising!
A few years later I bought a
4-channel 72 MHz Cirrus R/C system from Hobby Shack. The only interference
I recall with it was that loose metal-to-metal connections like between a metal
control rod clevis and a metal carburetor arm managed to get into the receiver and
cause the servos to jitter. That was remedied by substituting a nylon clevis. Such
were the trials and tribulations of early radio control. Now, the predominant
spread spectrum radios operating in the 2.4 GHz ISM band have almost totally
eliminated interference issues.
Editorial: FCC Secrecy of Communications CBs
An editorial by William J. Winter
'Youngsters with these noxious instruments hide at the edge of a model flying
area and try to knock planes out of the air!'
Most of us have knowledge of serious interference to R/C operations, which have
generally occurred on the 27-MHz spots, and virtually always have come from CB phone
transmitters. In many cases this interference has been caused by the unlicensed,
very low power "handy-talkies" (supposedly, they must have less than 100 mw input
to the transmitter stage connected to the antenna) right on the flying field, or
very near it. We've even seen cases where youngsters with these noxious instruments
hide at the edge of a model flying area and try to knock planes out of the air!
Some of this 27-MHz interference is accidental, of course. We operate on the
27-MHz spots under FCC provisions saying in effect that we must put up with any
non-intentional interference, since this band is in effect a wide-open party-line.
All well and good, when the interference comes from those using designated CB phone
channels, and who are operating their equipment in a legal manner.
Unfortunately, more and more CBers - though probably a relatively small minority
- are operating neither legally nor on legal CB phone frequencies. Some purposely
obtain R/C crystals, since our measly five channels (six, if you count 27.255 MHz,
which is in little use for R/C - due again mainly to intolerable interference) sound
pretty dead, when compared to the cacophony found on the 23 CB phone spots. This,
of course, is strictly illegal phone operation, compounded by the fact that such
operators generally utilize our spots for hamming - general chit-chat of the sort
quite common and legal on the amateur radio bands, but strictly prohibited (supposedly!)
on CB phone and R/C spots.
Individual R/Cers and clubs can do more than just gripe about such interference.
Send a report of the details to the FCC, with a copy to AMA Headquarters. If we
get enough such reports, possibly we can bring some pressure on the FCC through
We note these reports should be "detailed." By all means include dates and times,
frequencies, atmospheric conditions if you know them. We are on a high point of
the sun-spot cycle, and stations from thousands of miles away could be causing you
interference on 27-MHz. We hear that U. S. CB phone sigs are troublesome to R/C
flyers in England! Include the call letters of the interfering stations and their
locations if you know them. But do not include quotes from any conversations you
monitor. For reasons best known to the FCC, this is strictly taboo - a violation
of the "Secrecy of Communications" rules. You are not allowed to divulge such conversations
to anyone - not even the FCC itself!
Include in your report an account of any planes you are certain were "shot down"
by CB interference. You can certainly say in your report that you know the interference
was intentional, that it was on your R/C spot frequencies, from comments you heard
while monitoring - but again, don't quote or even summarize such comments. We know
this sounds like a stupid rule - it does to us, too. Especially, when it comes to
reporting what's heard on this "garbage band." But it's the law. Let's not get into
trouble by violating it ourselves.
The FCC took into account the serious interference problems to R/C on 27-MHz
when they allotted our 72-MHz band spots. Of course, there has been interference
there, too. But at least it has been "legal," as a rule coming from nearby TV stations.
Since the FCC has proven completely powerless to regulate the activities of CB
phone users (though they hand out dozens of stiff fines and license revocations
each week), we should undertake a campaign to gather documented reports of interference
on our R/C spots, particularly when it appears to be due to malicious or lawless
As noted above, send the report direct to FCC offices (Washington D. C. 20554),
with a copy to the AMA. And meanwhile - let's make sure our own house is in order!
Be sure all the flyers in your own group have valid licenses, and are operating
on permissible R/C frequencies.
Posted December 3, 2022