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Questions & Answers
These are the most common
problems with RC electrics.
|
Q
I get glitches when my engine is at
certain RPM. |
|
A
1.) PPM receivers. Turn on
the radio and tap on the receiver with the handle end of a small
screwdriver and watch to see if the servos jump when you strike the Rx.
If it does, something in the receiver is vibration sensitive in the
receiver. If not, tap on the switch harness, connectors, battery packs
etc. watching for movements in the servos. |
|
A
2.)
Look for metal to metal connections. Anything metal to metal will cause
this type of problem. One of the most common is a metal throttle arm on
the carburetor hooked to a metal clevis soldered to a metal control
cable hooked to the servo arm in the radio compartment. The noise is
generated at the clevis to arm joint and is transmitted through the
metal cable like an antenna into the radio compartment where the
receiver picks it up. Replace the clevis with a nylon type and the
problem will go away. |
|
Q
I have short ground range. |
|
A
1.) First, don’t test the
ground at the flying field with other people flying. Their strong signal
will degrade your receiver’s ability to see your weak signal. Do the
ground range test at home or at least with no other radios turned on. |
|
A
2.) Get the aircraft off
of the ground. Put it on a test stand, wooden picnic table, cardboard
box, etc. Make sure what ever it is, it is not metal or contain metal.
Remove the wing and pull the receiver as far out of the fuselage as you
can and remove the antenna from the model. Let the antenna dangle freely
from the model. Now do a ground range test. If it is still short, remove
the receiver completely and test it with a separate battery pack and
servo all by itself. If still short, the receiver and possibly the
transmitter need to be checked out at a repair center. If the
transmitter has good range with other receivers, the transmitter is not
the problem. |
|
A
3.) If you perform the
above test and you get good range with the receiver dangling outside the
model, then this tells you that it doesn’t like something inside of the
radio box or along it’s antenna run. Look for things like, antenna
running beside or through wire bundles, switches, touching servos or
servo wires. If you have long servo wires (24” or longer) that the wire
gauge is small, this will cause range problems. If you are running two
servos off of a Y harness, be sure you are using heavy gauge wires on
all extensions and Y harness’s. Servos that are starving for power due
to small wire size will surely cause problems for the entire radio
installation. |
|
Q
My airplane does something
unexpected during or after a maneuver. |
|
A
1.) If you are using nylon tubing type or cable type pushrods, make sure
they are secure at both ends and are not allowed to flex under strain.
You should be able to move your servo with the control surface without
flexing the pushrod. |
|
A
2.) Make sure everything
in the model is secured in its place. Something shifting position during
flight. Changes in the CG of your model during flight (say a battery
pack moving about) will cause some very erratic movements in your model
and can cause it to crash. |
|
A
3.) Check your servos for
smooth movement throughout their entire range of movement by very slowly
moving the control from one end to the other. Any bad spots in the
servos feedback pot will show up as a wiggle or jerk while moving. If
you find one servo with erratic movement, unplug the servo and plug
another servo into the same receiver port. Repeat the test. If it acts
the same as the other servo, the problem is in the transmitter in the
form of a dirty or worn control pot. This problem would need to be fixed
by me or some other qualified technician |
|
Q
Can I replace my receivers wire
antenna with a commercially available whip antenna and will I lose any
performance from my receiver? Should I have my receiver retuned to the
whip antenna? |
|
A
1.) There are a
number of antennas available. Some work and some do not. Some work with
certain brand receivers but not with other brands. Some simply do not
work with any brand! |
|
A
2.) You should
test each installation before you try to fly with any after market whip
antenna. Perform a ground range test before you install the antenna and
after. Install the antenna according the manufacturers instructions. Now
test the ground range again. If the antenna works as advertised, you
should not have a real noticeable drop in range. If you do, don’t use
it! Send it to me to test and tune for a real solid “go/no go” answer. |
|
A
3.) If you want the absolute
best possible performance from a whip antenna then you should send the
receiver and your whip antenna in for a tune up. Since the load is
different from the stock antenna, it will change the antenna coil tuning
even if only slightly. The charge to do this is $18.75. Justify the cost
of this with the amount of your investment in what you put in the air! |
|
Q
There are a number of whip antennas
available for transmitters. Are they safe to use? Do I need to have the
transmitter retuned to use a whip antenna? |
|
A
1.) Some
manufacturers offer whip antennas for their transmitters. You can be
sure that these will work just fine. Any aftermarket antenna should be
looked at as far as compatibility with your transmitter. |
|
A
2.) They are safe
to use only after you test them with your radio. This is a tougher test
for you to do yourself but you can do it. It is best done with a test
airplane that is a trainer type and will almost fly itself. Put the
model in the air and at first keep it out in front and fairly close in.
Gradually increase altitude. See how high you can get it overhead and
still see it well enough to know what it is doing. If everything has
gone well, then slowly start increasing the distance outward. Always
make sure you can see what the model is doing, if you can’t see it, you
can’t be sure if you have solid contact with the radio. If this test
goes well and you never lost radio contact, I would say it’s a good
match. |
|
A
3.) For absolute
best performance whenever you change to another type of antenna, it
should be tuned to your transmitter. Transmitters that use plug in
modules, it is each module that needs to be retuned. I offer this
service for $18.75 per transmitter or module (plus $5.00 shipping). |
|
Q
I have purchased a model and it came
with an older radio, it’s AM, I want to use it and was told it could be
upgraded to 1991 condition. What will it cost me to have it upgraded? |
|
A
1.) An older wide
band AM radio system upgrade only consists of a change in the
transmitters modulation circuit. This does narrow the output of the
transmitter so that it is less likely to interfere with other flyers
receivers but does nothing for your receiver’s performance. In fact, it
will degrade your TX to RX RF link. Your wide band receiver is looking
at a wider RF bandwidth for information needed to operate properly. When
you reduce that bandwidth, you make your old receiver useless. If you
fly it, you will most certainly crash. You can purchase a newer narrow
band aftermarket receiver, which will cost you about $80.00 if they are
still available. The batteries in the old transmitter are probably in
need of replacement at a cost of $36.00 or more depending on the
transmitter model. If you add up the cost of this so-called upgrade, you
are only a few dollars away from a new modern “safe” radio. Go for the
new radio and let the old radio die. |
|
A
2.) You could
have an older computer still in the original box never used that sold
new for $2000.00. But in the real world you would be lucky to get $5.00
for the whole thing today. And it maybe only 5 years old! RC radio
systems aren’t that bad but when you are talking about radios that are
10 years plus old, let them die! The newer FM radios since going narrow
band will hold their value better than those old computers will. |
|
A
3.) This is for the
modelers that will install an old wide band into an OK sellable beginner
type airplane just to unload a radio rather than trash it, shame on you!
You already had years of fun from that radio; don’t trick a beginner
into buying it from you at a bargain basement price telling him it’s
upgradeable! Whether you know it or not, you are cheating him and will
probably discourage him away from getting into this fine hobby. SHAME ON
YOU!!! |
|
Q
My transmitter won’t charge but it
turns on and everything else works fine. |
|
A
1.) There is
something wrong between the charge jack and the battery. Chances are it
is a blown fuse or blown fuse land on the pc board. |
|
A
2.) Some
transmitters use standard short fuses in their charge circuits. Some are
user replaceable (depending on your experience with a screwdriver and
confidence to mess with electronic equipment) and some are not. Call or
E-mail me with Brand and model no. for details. |
|
A
3.) Some
transmitters use fuse type devices called “IC Protectors” which look
like two legged transistors. These devises are buried in the PC circuit
board and almost impossible to find unless you know what you’re looking
for. I replace these devices with fuses that you can replace if you only
know how to solder. Cost, $12.50 plus 3.50 for the fuse (shipping
$5.00). |
|
Q
My transmitter is dead. Nothing at
all happens when you turn the switch on. |
|
A
1.) There is something wrong
between the charge jack and the battery. Chances are it is a blown fuse
or blown fuse land on the pc board. |
|
A
2.) Some
transmitters use standard short fuses in their charge circuits. Some are
user replaceable (depending on your experience with a screwdriver and
confidence to mess with electronic equipment) and some are not. Call or
E-mail me with Brand and model no. for details. |
|
A
3.) Some
transmitters use fuse type devices called “IC Protectors” which look
like two legged transistors. These devises are buried in the PC circuit
board and almost impossible to find unless you know what you’re looking
for. I replace these devices with fuses that you can replace if you only
know how to solder. Cost, $12.50 plus 3.50 for the fuse (shipping
$5.00). |
|
A
4.) In the case of
a computer transmitter, it could be a “hung” CPU IC chip. The CPU is the
computer chip and heart of the radio. Computers can be temperamental
things that react to static charges and other unknown voodoo spells that
few understand. Some are easy fixes and others are very costly. The
answer to this is to send the transmitter in to be “scoped” for
diagnosis. |
|
Q
My transmitter is
dead. Nothing at all happens when you turn the switch on.
|
|
A
1.) This is the result of
reverse charging a battery or hooking up a battery backwards. |
|
A
2.) In this case it will blow the main
voltage regulator first and then “hang up the CPU”. The memory battery
will drain within 5 minutes and you are done! The radio is useless from
this point on. |
|
A
3.) This must be sent in to be
corrected. Only after it is “scoped” can the damage be assessed. Price
to correct can range from $35.00 to 150.00 depending on how the reverse
voltage damage was incurred. |
|
Q
My computer transmitter is doing weird things when
I input controls or flip switches. |
|
A
1.) Anytime your computer
transmitter is doing things that you do not understand or did not
program it to do, you need to reset its memory back to the factory
default program. This will wipe out anything that you are not aware of
that might be programmed into the computer. Start programming the model
from square one. This usually clears up these types of problems. Don’t
waste your time in trying to figure out what the problem is. You won’t!
Just wipe it out and start over. |
|
Q
My Aux switch or lever doesn’t work on my computer
transmitter. |
|
A
1.) The switch is not
programmed. Look in the manual under programming related to switch and
lever assignment control. |
|
Q
My computer transmitter won’t hold what I program into it overnight.
Everything else works fine. |
|
A
1.) Most computer transmitters use a
3 volt lithium batter to hold the memory of the computer safe while the
transmitters switch is in the off position. It does not consume any
power from the battery and should have a life comparable to the shelf
life of the battery hooked up to nothing, whatever that may be (12 years
or more) unless something upsets the CPU IC. If the CPU hangs, it will
kill the memory battery in about 10 minutes. You will get a “Memory
backup error” message after that. The CPU needs to be reset, memory
battery replaced, and the factory default program calibrated. You cannot
do this. You need to send it to me for service. Cost, $25.00 plus any
parts needed. |
|
Q
My transmitter keeps blowing fuses. |
|
A
1.) Check your plugs on anything you
plug into the charge jack. You have one of those plugs tip insulators
damaged or missing that causes a dead short as you plug the plug into
the radio. Inspect all plugs, charger, quick charger, expanded scale
voltmeter, etc., for damage to the plastic insulator located at the tip
of the plug. If it is missing, worn, or damaged, replace it. A
replacement can be found at any electronics store. Cut off the old one
and take it with you so you are sure to get the right one from the
salesperson. |
|
Q
My computer transmitter beeps when you tap or shake it. It also turns
completely off if you hold it just right. |
|
A
1.) You probably replaced the
fuse lately. Some fuse holders don’t hold their shape very well. They
will bend when replacing the fuse and not hold the fuse tightly and
allow them to make intermittent contact. To correct this problem you
must remove the fuse and carefully squeeze the fuse holder together.
Reinsert the fuse and check that both ends of the fuse is being held
tightly. This can be tricky at times! It may take several tries to get
it right. |
|
Q
I just bought a new Berg 6 receiver and it won’t work even though I
bought the right one to work with my brand of transmitter. It will work
with my buddy’s transmitter, which is the same type as mine. What’s
wrong? |
|
A
1.) The Berg 6 receiver was designed to
be one of the tightest banded receivers on the RC market. One drawback
is not really the receiver’s fault, but it requires the transmitter that
is driving it to be more accurate in its frequency shift transmission.
Mass production of a product will allow for allowable tolerances in the
assembly line. That means that to work with each manufacturers products
these tolerances can be kind of sloppy when a new product is introduced
in the marketplace. This is no fault of the original manufacturer, but
is a requirement of the new piece of equipment. Some transmitters will
require adjustment to its frequency shift in order to operate with the
Berg 6 FM receiver properly. Charge for this service is $15.00 (plus
$5.00 shipping). |
|
A
2.) The frequency |
|
Q
Some times my radio will work and sometimes it only surges the servos
when I turn the airplane on. |
|
A
1.) The surge you see in your servos
movements is normal and happens everytime you turn your receiver on. But
normally after you power up the airborne system the signal from the
transmitter comes through and the servos return to their commanded
positions. In this case there is no signal coming through the receiver
to command the servos so they just stay off center, dead. The most
common cause of this is a weak rx crystal. If you have access to another
crystal of the proper brand and channel, try swapping them. If it starts
working when you power up, you have a solid answer as to what is wrong.
Simply replace the crystal and go on. If the new crystal exhibits the
same problem in the future, there may be a off frequency problem with
either the receiver or transmitter that needs looked at. A simple
adjustment in either should cure the problem but it is an adjustment
that only a qualified technician can perform. |
|
A
2.) This can also be a tuning issue in
either the receiver or transmitter. If the frequency deviation is near
the outer limits of operation in either transmitter or receiver, your
system could exhibit this kind of behavior. Both transmitter and
receiver should be looked at by a qualified service technician. |
|
Q
My helicopter has real short range when I turn the gyro on. But when the
gyro is off, the range is good. |
|
A
1.) This usually indicates that you
have a high impeedence connection in the onboard power system. You need
to isolate the bad connector or device by trying one thing at a time.
First try unplugging the switch harness and plug the battery directly
into the receiver. Try a range test with the gyro on again. If range is
normal, replace the switch harness as this is the culprit. If range is
still short, replace any wiring past the switch harness leading to the
battery pack. Even try replacing the battery. After each change, perform
a range check until you have isolated the trouble making part. Good
luck! This is a frustrating problem to chase down. |
|
Q
My helicopter’s tail wags when I am in forward flight. |
|
A
1.) Turn the gain of the gyro down a
little bit at a time until the wag stops. Now this is the maximum
sensitivity you can operate the gyro at for your present setup. |
|
Q
My helicopter use to have good range and was rock solid. Now range is
erratic and gets hit even at close range. It’s totally unstable! |
|
A
1.) This is one of the strangest cures
I have ever seen, but not the strangest symptoms. Helicopters are famous
for causing havoc to an R/C radio systems ability to function properly.
I had a customer call me with a helicopter that just the day before flew
perfectly and had since he first built the machine 6 months prior to
that. Overnight the machine became unflyable. We tried for days
replacing bearings, looking for metal to metal problems. Nothing he did
changed anything. I told him to try to think of the last thing he did to
the heli between the time it had flown perfect and when it became the
heli from hell! He called me back a few days later and told me he had
fixed the problem. The last thing he did he remembered was to clean up
the machine which included waxing the fuselage. The problem cropped up
after that. Maybe a static charge built up on the fuselage? If that was
the problem, maybe wiping the fuse down with Static Guard could help. He
did that and the problem disappeared and has not returned to this day. I
know it sounds silly, but logical if you think about it. |
|
Q
What is a single rate gyro and what is a dual rate gyro? |
|
A
1.) A gyro’s sensitivity adjustment is
usually refered to as it’s “rate”. It is set using a pot on the gyro and
controls the amount of opposite control it feeds the control servo it is
hooked up to when movement about it’s control axis occurs. This will
counteract unwanted movement of the model caused by changes in torque or
wind. A single rate gyro only has one sensitivity control and that is
located on the gyro and can only be changed while on the ground at the
gyro. A dual rate gyro has a lead coming from the gyro that you plug
into an aux channel to control the rate from your transmitter by
changing the control channel that the gyro is plugged into. There
usually is a main rate control on the gyro itself that controls the
maximum amount of sensitivity that can be used at the transmitter and
you can not achieve more than the amount set from the gyro. |
|
Q
What is “Ground range” and how do you test for it? |
|
A
1.) Ground range is the
distance you are able to walk away from your model and maintain control
with the antenna of your transmitter fully collapsed. This will give you
a reference as to your radio’s performance level. You should also test
your ground at the beginning of each days flying session. It will warn
you of any problems in your radio system before you put in the air. If
your ground range is suddenly shorter than it was before, do not fly.
Find out what has changed and correct it if you can. |
|
A
2.) First, don’t test the
ground at the flying field with other people flying. Their strong signal
will degrade your receiver’s ability to see your weak signal. Do the
ground range test at home or at least with no other radios turned on. |
|
A
3.) Get the aircraft off
of the ground. Put it on a test stand, wooden picnic table, cardboard
box, etc. Make sure what ever it is, it is not metal or contain metal.
Remove the wing and pull the receiver as far out of the fuselage as you
can and remove the antenna from the model. Let the antenna dangle freely
from the model. Now do a ground range test. If it is still short, remove
the receiver completely and test it with a separate battery pack and
servo all by itself. If still short, the receiver and possibly the
transmitter need to be checked out at a repair center. If the
transmitter has good range with other receivers, the transmitter is not
the problem. |
|
A
4.) If you perform the
above test and you get good range with the receiver dangling outside the
model, then this tells you that it doesn’t like something inside of the
radio box or along it’s antenna run. Look for things like, antenna
running beside or through wire bundles, switches, touching servos or
servo wires. If you have long servo wires (24” or longer) that the wire
gauge is small, this will cause range problems. If you are running two
servos off of a Y harness, be sure you are using heavy gauge wires on
all extensions and Y harness’s. Servos that are starving for power due
to small wire size will surely cause problems for the entire radio
installation. |
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