COMPARISON OF 2.4 GHZ RADIOS

                                                     By: Ron Scott  2-9-2009

 

The following is a summary of my own experience with 5 different 2.4 GHz radio systems related to flying 42 different model airplanes over the past 2 years. I hope it helps someone out there.

 

Background: I probably fly more then the average modeler and average 4 to 5 days of flying per week.

I belong to 5 RC flying clubs in the southern California region and have over 200 planes. (Obviously I’m not married) Most of my planes are Glow and Gas powered from size .10” to large 35% Extra 330 with DA 100 or similar engines. I have 62 Electrics from Zagi style flying wings to pattern planes and float planes. Also, numerous gliders from hand launch to slope to large 10 foot wing span thermal gliders. The reason I tell you this is because the point is I fly a lot and believe that this makes a good test bed for trying out new equipment.

Keep in mind for what it’s worth - my write-up is only one man’s opinion. Ask 10 people and you’ll get 10 different answers.

 

R/C Radios tested:

     1) Spectrum DX7  - 7 Channel System

      2) Futaba T6EX and T7C – 6 and 7 Channel System

      3) Assan (from Hobby City) XR8 Plug in Module to a Hitec Eclipse 7 (or Optic 6) Transmitter.

      4) Airtronics RDS 8000 FHSS – 7 Channel System

      5) EF Helicopters  EF 2401 – 4 channel for helicopters (from Hobby People)

                                    

Spectrum DX7 :  Cost ~ $300 – 350, I have 12 models (mostly foamies) on this radio system.

 

           Likes:              Easy programming & big LCD display showing curves, has 7 channels, model

                                    matching, 20 model memory, 1500 mAh battery. Receivers (AR500 and AR6100

                                    and AR7000) cost between $50-90. More expensive receivers are available.

           Dislikes:     1)             Charge jack is different from most other manufactures, + is outside and – is

                                             inside connector. (When are they (JR) ever going to convert to match most

                                              other  manufacturers chargers i.e. + = center pin and  −  = outside plug ?????)

                               2)         Loss of control – I have had 3 planes lockout (or brownout) for 2-4 seconds

                                              and crash. Later found that if I put a 4,700 µfd cap across one of the receivers

                                              output channel + and –  pins the problem went away. (Horizon sells a 4,700

                                               µfd capacitor that  eliminates the lockout potential problem for $6.00 – called a

                                                                       “Voltage Protector”). What  actually was happening was a momentary drop in

                                    voltage (+5 to ~3-4 volts) on the ESC power line BEC going into the receiver as

                                    a result of a momentary hi current draw on the battery. There are at least 2 other

                                    ways  around this potential problem. One is by providing a separate battery (4-5

                                    cell) to power the receiver only. The other way is to install a separate BEC device

                                    to supply 5 Volt input to the receiver. A company called “Dimension Engineering”

                                    (Dimension Engineering.com on the web) makes a “ParkBEC” and a “Sport BEC”

                                    for $19-$30 to eliminate or reduce the possibility of a brownout condition.

                                        In all fairness, the ESC’s play a major role in the radio’s ability to function

                                    properly. The receiver may be falsely accused of being the problem source – but in

                                    actuality the BEC circuit of the ESC may be limited and not be able to supply a

                                    solid + 5 volts to the receiver. So, check out your specs when you put together your

                                    next Electric plane. Now the question is, why doesn't Spektrum offer a free 4,700

                                    µfd capacitor for every radio receiver they sell?

                                                      − 1 −

 

 

                              3)  “BACKUP ERR” displayed on the display after power up. The transmitter

                                    would not recover  and had to be sent back to Spectrum and they replaced the

                                    transmitter because they could not fix the “Backup Error” problem.  ?????

                              4)         Binding problem – Had to bind 3 times before one model finally held a bind.

5)      Fuse blowing problem –  On occasion if you fast charge the transmitter battery at  2-2.5 amps  the internal 3 amp fuse occasionally blows.

                              6)         No Throttle Cut or Throttle lock button or switch – to prevent from accidental

                                    moving the throttle lever up. (very important from a safety standpoint)

                              7)   Switches are not programmable i.e. you can’t make certain switches set for Retracts

                                    or Flaps, etc. (like Futaba).

 

Futaba T6EX &T7C systems:  Cost ~ 200 - $300

                                     Good solid systems – I have had 7 models flying for 6 months with no problem.

 

      T6EX    Likes:     Easy programming and solid communication – No crashes. Programmable, 6 

                                      model memory,

 

                 Dislikes: 1)  Receivers are $90-100.

                                 2)  Only one dual rate switch for the ailerons, elevator and rudder.

 

       T7C      Likes:     Easy programming and solid communication – No crashes. Programmable

                                       switches, throttle cut, 10 model memory.

 

                  Dislikes: 1)  Receivers are $90-100.

                                  2)  Chrome plating on the face is starting to crinkle and bubble up in certain areas.

 

Airtronics RDS 8000 FHSS:   Cost ~ $230

                            Good System so far – I have had 2 models flying for 2 months with no problems.

 

                      Likes:  Easy programming, additional receivers are $70.

 

                  Dislikes:  Only has 3 letters for model name and there is no dual rate or Exponential for the

                                   rudder.

                      

 Assan (from Hobby City) XR8 Plug in Module to a Hitec Eclipse 7 (or Optic 6)

                             or Futaba 72 MHz Transmitters.  Cost ~ $65 - $75 (There are also plug in

                                  modules for JR Transmitters) This module actually takes a 72 MHz transmitter up to

                                  2.4 GHz. Check it out at WWW.hobycity.com and go to their 2.4 TX/RX

                                  Systems and Parts section.

                                  I have 9 models on this System – So far, no problems except as noted below.

 

                       Likes: Easy to install and use in my Hitec Eclipse 7 (or Optic 6) or Futaba 9C Transmitters.

                                   Very reliable, don’t have to learn a new system, Cost only $68 for module and

                                   receivers are very affordable @ $24 (Close range 4 channel) – $75 (for an 8

                                   channel) full range receiver. Also, you can go back to 72 MHz with original module.

                                   Receivers come with a 4,700 µfd capacitor to prevent potential “Brownouts”.

                   Dislikes: Nothing, except for one 8 ch. receiver that wouldn’t bind and had to be sent back

                                   for  replacement (which took 10 weeks – from Hong Kong) L.

− 2 –

 

 

 

EF Helicopters:   Cost $120.  Model EF 2401 – 4 channel for helicopters (from Hobby People)

 

                    Likes:   Simple dual rotor easy to fly helicopter – no problems.

 

                Dislikes:   None, this is a very simple system and  I have only limited experience with

                                     Helicopters.

 

 

 

 

Summary:  If I were to recommend a 2.4 GHz system to a fellow modeler I 

                     would have to go with the following.

 

                # 1 Assan – Assuming that you have a Hitec Eclipse 7 (or Optic 6),

                                     JR, or Futaba radio that uses a plug in module.

 

                # 2 Futaba T7C − But be aware of the receiver cost (~ $100).

 

                # 3 Spectrum DX7 − But make sure you install a 4,700  µfd

                            capacitor across the + and − terminals of the receiver.

                            (Voltage protector – Horizon Hobbies @ $6)

 

                #  4 Airtronics RDS 8000 FHSS

 

 

 

 

Side Note:  The best thing about the 2.4 GHz R/C systems is that to my knowledge,

                   I haven’t had a crash due to a fellow modeler being on the same channel

                   (as in the 72 MHz band).

 

 

 

Good luck and “Happy Landings” ……………………..

 

Ron Scott, ………………………………………..

 

 

 

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