bought a raptor 30 with a fp-r127df receiver and i have a rd6000 super transmitter. when i turn the TX on all the servos go crazy then stop, the controls only work when im practically on top of the unit, or they just do their own thing. when i am more than 6 feet away the controls do not work. i was told the ppr setting is what i want for this receiver. could it be the crystals i put in? do i need certain ones? i used the crystals from my axe cp...from what i have read these are single conversion crystals,,,what will putting single crystals into a dual conversion receiver do? thanks

Hope this helps!


Transmitter Radio Characteristics
Modulation - method used to encode the control information from your sticks, knobs and switches into radio waves.
AM - Amplitude Modulation, the amplitude of the radio wave changes when you move your controls. Generally regarded as cheaper, having less range and also less features. Also, they are known for radio interference problems. For antweights, range is not an issue, but these radios are generally regarded as low end and used in toys.
FM - Frequency Modulation, the frequency of the radio wave changes when you move your controls. The amplitude is kept constant. Two common types of FM are PPM and PCM
PPM - Pulse Position Modulation - the data is encoded in frequency pulses in which the position of the frequency changes. The most common type used, some of the cheaper ones are comparable in cost to AM.
PCM - Pulse Code Modulation - Proprietary data encoding where the data is transmitted in a series of 0 and 1s, just like a computer communications protocol with error checking. Each manufacturer has their own protocol and you cannot interchange PCM gear from different manufacturers. These radios cost more than regular FM without PCM, but typically have a PCM/PPM selection to allow you to use non-PCM receivers to save weight.
For more info: http://www.rcfaq.com/answers/radio/

Frequency - radio frequency/channels used to transmit the control signal. Radio channels are assigned to frequencies and there are different frequency bands available to use. This applies to both AM and FM.
Aircraft only bands 72MHz Band, Channel 11-60.
Ground only bands 75MHz Band, Channels 61-90
All uses 27MHz Band, Channels A1-A6
All uses but must have an FCC Amateur license 50MHz Band, Channels RC0 - RC9
For more info: http://wireless.fcc.gov/prs/radcntrl.html


Shift - Applies to the radio signal decoding that different manufacturers use. You only care about this when you are mixing Tx and Rx from different manufacturers.
Positive Shift - Method used by JR and Airtronics
Negative Shift - Method used by Futaba and Hitec

Other Info on Transmitters
Narrow Band- In 1991, the FCC mandated that RC had to use a smaller band so they could fit more channels into the frequency bands. Before 1991, the width of a band was 40kHz, now its 10kHz.
More info: http://www.futaba-rc.com/faq/service-faq.html#q41
Crystals – Channels are selected by a crystal and by simply swapping out matching crystals on both your transmitter and receiver, you can change the channel you are using.
Control Channels – Not to be confused with the radio channel (frequency), each radio can control only so many outputs. These are referred to channels. Typically you will find 2-channel, 3 channel, 4-channel, 6-channel, 8-channel and 9-channel. You need to select a radio that has enough channels to drive your robot. More channels cost more. For example, if you have a robot that only has 2 motors and no weapon, a 2-channel radio would work, one each wheel. If you have a weapon, now you need 3 channels. Usually its better to have more channels in case you want to add more things later. For an antweight, 4 channels would be enough for 95% of the robots.
Mixing – Typically used for drivetrain. You want to mix your single control stick so it drives your right and left motors. When you push forward, you want both motors to drive forward. Same with reverse. When you push the stick left, you want your left wheel to turn in reverse and your right wheel to turn forward so your robot spins. Radios don’t typically do this and require mixing. Cheaper radios don’t allow you to mix in the radio while the computer radios will let you set it up that way. If your radio doesn’t do mixing, you can obtain mixers that you can install on your robot.


Receivers Radio Characteristics
Receivers are very important to antweights, with 16 oz of weight to work with, you want the smallest and lightest receiver you can use. Typically the receiver that comes with your transmitter will be bigger and heavier than what is available.

Conversion – Receivers come in 2 flavors, single conversion and dual conversion. Dual conversion filters the incoming signal in 2 steps rather than one (as with Single Conversion) thereby eliminating more interference and glitches. The conversion type has nothing to do with the radio signal being transmitted, just how the receiver decodes or converts it. Single conversion receivers tend to be cheaper and lighter and ideal for antweights and can be used with any transmitter as long as they are on the same channel and same modulation type. Single conversion receivers typically come with 4 channels maximum.
Never use dual conversion crystals in a single conversion receiver or vice-versa. It won’t work.



Products – Below is a list of various small and lightweight receivers. You will notice that the lightest receivers are aircraft frequency. This is because they are typically used in super-lightweight indoor aircraft. As antweights take off in popularity, I’d expect to see some lighter ground frequency receivers.
I also added a list of aircraft receivers to show how much lighter they can be!

The list is incomplete, but represents the lightest receivers I have found. E-Mail us if you know of any others we should add to the list.




Micro Receivers - Ground Frequencies (27 & 75 MHz)
Manufacturer Part/Description # of Ch Conv Freq (MHz) AM or FM Length (in) Width (in) Height (in) Wt (oz) Notes
Airtronics 92721 / 92723 3 Single 27/75 AM 1.89 1.20 .76 0.75
Futaba R123F 3 Single 27 & 75 FM 1.50 1.00 0.63 0.72
Fury 404FM75 4 Dual 75 FM 1.82 0.94 0.67 0.60
Hitec HFS-02MB 2 Single 27 & 75 AM 1.20 1.90 0.70 0.81
Hitec HFS-03MM 3 Single 27 & 75 FM 1.20 1.90 0.70 0.81
Hitec DCX 3 Dual 27 & 75 FM 1.60 1.10 0.70 0.75
Novak XXL 2 Single 27 & 75 Both 1.29 1.11 0.53 0.48 Lightest Ground Rx
Novak XXTra 5 Single 27 & 75 FM 1.65 1.12 0.51 0.59 Channel Synthesizer

Micro Receivers - Aircraft Frequencies (72 MHz)
Provided for reference only, these frequencies are not allowed at SOZBOTS events.
Manufacturer Part/Description # of Ch Conv Freq (MHz) AM or FM Length (in) Width (in) Height (in) Wt (oz) Notes
Maxx MX-6800 4 Single 72 FM 1.17 0.44 0.47 0.25
GWS GWR-4P 4 Single 72 FM 1.00 0.59 0.37 0.16 Lightest Aircraft Rx
Hitec Feather 4 Single 72 FM 1.30 0.80 0.40 0.26

The last one talked about robots so here is a link that talks about planes. Didn't read about the "weapons" on the robots until after i posted it. I just google searched your question and found answers. I'll have to go back ans take another look at that website.




http://www.modelaircraft.org/mag/FAQ...rs/faq-q34.htm

DF = Dual Conversion FM so it needs a Futaba, dual conversion FM reciever crystal on whatever channel your transmitter is on.

Next, Airtronics is positive shift, Futaba is negative shift so if the radio doesn't allow you to change the shift type it won't work anyways.

Last, mixing and matching crystals w/o knowing what you are doing where a nitro rc helicopter is concerned is taking your life, and that of any spectators in the vacinity in your hands. You were lucky to get the results you did, if had worked on the bench and not in the air you could have had a handful of trouble on your hands.