LegaL and/or illegal transmitters are
the subject of a letter from Charles Reich of
St. Augustine FL.
“I recently attended our local club
meeting, where our president announced:
“‘OK, now I hope all you guys realize
that the new FCC [Federal Communications
Commission] rules are now in effect
regarding transmitters. We’ll probably
ignore, or turn our heads, out at our field, to
those of you using old type transmitters for
the time being. Especially considering the
remote area of our flying field and little
chance of causing interference. Be aware
that if you attend AMA sanctioned contests
you will all need to be using legal
transmitters.’
“I then asked a stupid question: ‘With
the plethora of different brands, types, and
markings on the backs of transmitters, how
will the CDs [Contest Directors] know
what’s legal and what isn’t? Better yet, how
do we know which of our own transmitters
are legal, how do we tell?’
“Everyone looked at each other in
dismay, shrugged their shoulders, and the
meeting went silent before quickly changing
to a new subject. This may be a good topic
for one of your articles. As you are well
aware, many of the transmitters carry the
gold trapezoid-shaped label reading:
‘R/CMA Recheck, AMA Date:’
“Some have dates stamped or
handwritten in, others are blank.
“I just counted and I have nine different
transmitters, all with different markings on
the back. A couple I sent to Futaba a couple
of years ago to be updated. The only
marking they have is the trapezoid-shaped
gold R/CMA Recheck label on the back.
“The CDs are going to need some type of
guidelines to know what is legal and how to
identify them. I’m fairly sure not all CDs are
well-informed on this matter.
“There are literally thousands of used RC
[Radio Control] rigs that show up at every
major swap meet. How will the average
modeler know if he’s buying a unit that is legal
with today’s FCC rules? This information will
be invaluable to the used market buyers,
especially if they start enforcing this new law.
“I don’t think the transmitters are
grandfathered in, as are the receivers. Also
of interest would be information regarding
the procedure and/or possibility of sending
our transmitters to a service center marking
them as such for CDs and our own relief.
What vintage or types of transmitters might
fall within this possibility, if any?
“Hopefully you can come up with an article
that explains the new rules, and what’s legal and
what ain’t—and how to tell if our own units are
FCC legal—before we get to a contest.
“Thanks for listening and your consideration
of an article for this subject matter.”
Most of the information Charlie
requested is published annually in the AMA
Membership Manual.
Additional valuable information about
transmitter and receiver quality and testing
is included in George Steiner’s A to Z—
Radio Control Electronic Journal ($20.15
postpaid from GSP Products, 2238 Rogue
River Dr., Sacramento CA 95826).
Since you may not read everything that
comes your way, unless it is of immediate
interest, I’ll review the information for
Charlie and his friends. I’ll start with the
narrowband requirements as they affect us RC
fliers!
Our frequencies, available through the
AMA’s efforts and the FCC’s blessings, are
at 20 kHz (kilohertz, 1,000 “cycles” in the
old vernacular) spacing. The actual
transmitted signals are narrower than in the
Kraft and Orbit days, and understanding
signal quality requires more explanations
than are necessary for this discussion.
“Narrowband” is not an absolute value, but
is used in this case to designate a signal smaller
in width than our old “wideband” equipment.
Think of an RC channel as a given
space—it has a certain width! As long as
everyone stays within his or her allotted
space, there are no problems.
However, if someone spills over, he or
she will cause problems for the user of the
adjacent space and vice versa, and that
person’s spillover will create problems for
the next user.
There are two considerations: the
transmitter and the receiver.
You need a narrowband transmitter so you
won’t create problems for the user of the
adjacent “spaces.” You need a narrowband
receiver to prevent interference to you if an
adjacent user takes up more than his/her
assigned space.
Look at our RC equipment. The
transmitter label mentioned doesn’t read
“Recheck,” but “RF [Radio Frequency]
Check.” And the transmitter narrowband
requirement is federally imposed by the FCC,
which controls everything capable of emitting
radio waves, from radio and televison
stations, down to your kid’s walkie-talkie.
Even included are word processors,
microwave ovens, television receivers, etc.—all
of which emit radio signals we perceive as noise
and static, that is interference to RC equipment.
However, the FCC does not impose the
same narrowband restrictions on receivers;
that is strictly an AMA requirement—one
that benefits all of us.
Receivers have stickers reading that they
comply with Part 15 of the FCC’s ruling,
January 2001 97
Eloy Marez
E l e c t r o n i c s
2626 W. Northwood, Santa Ana CA 92704
Now RK Products Lil’ Trickler has a more-capable family member. Details in text.
but that refers to their radio frequency
emissions being within certain limits—not
their narrowband abilities.
The term “double conversion” has come
into vogue with the narrowband requirements.
In all receivers—including non-RC types—
the incoming operating frequency is first
converted to the “Intermediate Frequency”
(IF)—455 kilohertz (kHz) in singleconversion
receivers.
In double-conversion units, the frequency is
first converted to 10.7 or 11.155 megahertz
(mHz), then to 455 kHz. The latter is the
frequency at which all signal-processing takes
place.
You might think a great deal of testing
led to the selection of those frequencies, but
that’s not the case. The frequencies are used
because the necessary components for them,
such as coils and crystals, are used by the
millions in consumer products throughout
the world. Therefore, they are readily
available and inexpensive.
All RC aircraft frequency receivers on
the market are double-conversion, with two
exceptions.
One is Hitec’s HAS-3MB, furnished with its
neat little Focus 2 and 3 single-stick systems.
Both units are also unique because they are AM
(Amplitude Modulation). The receiver is said to
be “Super Narrow Band,” and it works well. I
don’t have any other circuit details.
The other single-conversion receivers are
available from JR, which advertises its
receivers as featuring patented circuitry
described as Anti-Blocking, Cross-
Modulations and Window (ABC&W).
I have never seen an explanation of this
technique, nor is it used in any other non-RC
application I know of. Whatever electronic
magic it may be, JR receivers have a
reputation for reliability and dependability.
You may have seen an ad implying that “X”
company developed double-conversion circuitry
just for the RC flier. Not so; it was common in
non-RC communications receivers long before
we heard of it.
I owned a Ham receiver that used moreadvanced
triple conversion 40 years ago, and
they are not uncommon.
I’ll mention the following because it has
been brought up in incoming correspondence:
double-conversion circuitry is not used or
required in transmitters.
What might have confused writers is that
some RC crystals in use are cut, i.e.,
manufactured, to the basic frequency, while
others are half-frequency and multiplied
within its related circuitry.
It could pose a problem for transmitter
identification, but only if the owner has been
mislead, or is attempting to mislead a contest
official.
Effective January 1, 1995, AMA
dropped the Gold Sticker RF Check
program; the stickers are no longer required.
As of March 1, 1992, all transmitters
(receivers are exempt from FCC narrowband
requirements) “type accepted” (approved) by
the FCC must be narrowband. Test results from
an independent FCC-approved laboratory must
be filed for each transmitter type.
Manufacturers and dealers were given a
one-year period to move older stock; as of
March 1, 1993, all transmitters marketed
had to be narrowband.
We were given until March 1, 1998 to use
and have upgraded older wideband transmitters;
as of that date, upgrading of transmitters by
anyone (whether it’s a manufacturer or
independent service center) was prohibited!At
that time, it became illegal to modify a wideband
transmitter to operate on narrowband.
At least two service centers advertise
transmitter narrowbanding. I’ll give them
the benefit of the doubt, and say that maybe
their ads need updating. If they are doing so,
they are outside the law, and those flying
with such equipment are also in violation.
Above I refer to transmitters only. It is not,
and never has been, possible to narrowband
an older receiver; the printed circuit board
will not accept the additional circuitry. The
only cure is a receiver designed as a
narrowband unit from the beginning.
Identification of legal transmitters can be a
problem. Basically the only definite is that AM
types no longer fit the bill, with the exception
of Hitec’s Focus 2 and 3 transmitters. They are
AM, but they fall under the “after 1998”
category and must meet the FCC specs.
We can also assume that all “RF Check”
gold-labeled transmitters are legal; they were
marketed or tested during the labeling period.
As Charlie wrote, many of the transmitters
98 M ODEL AVIATION
do not contain a date, which the importer was
supposed to enter at the time of shipping.
That was largely ignored, even by the largest
RC supplier.
True, CDs aren’t expected and shouldn’t
be expected to know what is and isn’t legal,
although the stated guidelines can be used.
Be prepared when you head for an AMA
sanctioned meet with questionable
equipment—just in case.
Your dated bill of sale should work, as
will its manual, and probably a magazine ad
describing your particular system. You
might have to query your equipment’s
importer about its narrowband features.
I cannot imagine (from the perspective
of a cut-and-glue builder) trusting an
airplane to one of the many old, used radio
systems in unknown condition—especially
when you can get a new, modern, legal
system, complete with four servos and
brand-name Ni-Cds, for roughly $100.
Lil’ Trickler Multi: First there was RK
Products’ Lil’ Trickler—an adapter that you
plugged into the wall socket between it and
your normal system charger.
Its function was to reduce the charger’s
output to a reduced “trickle” rate, at which
most Ni-Cd battery manufacturers
recommend be applied consistently to
prevent battery self-discharge and to keep
the batteries topped off.
The Sanyo Electric Co., manufacturer of
the well-known Ni-Cd cells of the same name,
specifies this value as between C/20 and
C/50—the cell capacity in milliampere hours,
divided by any value between 20 and 50.
Since many users felt the need for more
than one unit, RK Products has introduced a
triple-function version: Lil’ Trickler Multi. It
is designed to support three Ni-Cd chargers in
the same manner as the single-output version.
Plug Lil’ Trickler Multi into the wall
outlet, and plug the charger(s) into it.
Normal charging is recommended first, then
a switch on the Multi is set to “Standard”;
an LED (light-emitting diode) indicates
switching to the trickle mode.
The LED on the charger may or may not
remain on, depending on the current rating of
the charger and the number of cells connected.
The Multi can be used with all Ni-Cdpowered
devices, such a drills,
screwdrivers, and even toothbrushes!
The device is rated for a maximum of
seven watts per outlet. It’s no mystery, but
watts is the product of voltage multiplied by
current. The Airtronics charger is label-rated
at 6.0 and 12 volts at 75 milliamps. This
calculates to .45 and 9.0 watts respectively, or
a total of 1.35 watts—well within the ratings.
My tests of the Lil’ Trickler Multi showed a
reduced output to approximately 1⁄3 of the
charger’s normal rate. A 700 mAh battery
charged at the recommended C/10 rate (70 mA)
will reduce to slightly more than 20 mA with
the Multi switched on—well within the C/20
(35 mA) and C/50 (14 mA) recommended rates.
The Lil Trickler Multi is $29.95 plus $4.50
shipping, available from RK Products, Box
950547, Lake Mary FL 32795-0547. MA
