Large Scale Central

Spektrum DX5e 2.4 GHz Spread Spectrum Radio

Electronics Power and Sound
#1

With the release of the Spektrum DX5e Radio offering 2.4 GHz Spread Spectrum performance for under $100, it’s time to upgrade the radio system in my live steam Shay. I originally installed a Futaba AM radio and have not been happy with the resolution or the glitching on the cheap radio system.

The DX5e was designed for aircraft use, but from what I can find on the web, the 2.4 GHz band is used by either surface or aircraft. The one thing I’m not sure of is how the throttle stick works having never flown R/C aircraft. For the Futaba radio I installed an optional Ratchet Clip on the throttle stick so that it would not spring return to center, but rather stay where it was set. I’m assuming that aircraft radios come with the throttle stick already set up that way, but I can’t find any info on-line.

So - someone who flies R/C planes - Can you tell me if the throttle needs to be held open (like an R/C Car) or does the stick stay where you put it? How about the other 3 control surface sticks?

For now I am only using the throttle stick to control the Johnson Bar. This gives me both speed and directional control on one stick. In the future I may want to add a servo for the throttle. When I do that I’ll want two sticks that stay where I put them.

#2

Jon - I checked their manual and it doesn’t really say if the sticks can be modified or not. I am not an R/C flyer, but I have a couple of 4+ channel radios here, and both of them work like this - The left stick ratchets (stays in a fixed position) up and down, and is return to center left and right. The right stick; both up and down, and left and right return to center.

I was looking at this radio a few weeks ago, and the thing I don’t like about it is the size. It is pretty huge.

#3

If its an aircraft radio (not helicopter) the throttle stick stays where you put it.
As far as size goes, just use a neck strap. It keeps the radio in front of you hands free. The Spektrum antenna on the radio is very short so you won’t be “puttin’ your eye out” with it.
The small receivers with their short antennae are very applicable to model RRing.
Spektrum technology-2.4g- is the wave of the future in RC flying. In fact its the way of the present. The ability to operate without interference from others’ radios is really great. I was at an event this summer where there were over 300 registered pilots. Flying with my Spektrum equipment sure eased my mind knowing that it would be almost impossible to be shot down by someone firing up their radio.

Dave

#4

Thanks Del & Dave. That’s how I imagined it would work and I can deal with that. Spektrum does make a ratchet strap for one of the other model radios - it might work in this one as well since I doubt they have multiple molds for the stick gimbals.

The size doesn’t bother me. I was using a Futaba Attack which is almost as big with a long antenna. It will be great to be able to run my steam engine smoothly. The glitching I get on the Futaba make it run like a sparky on dirty track.

#5

One other quick question for Del, assuming you are using your 4 Ch. radio for steam… If you use the Throttle stick for the engine’s throttle, what stick do you use for the reverser (Johnson Bar) ? Seems like it would be a pain to hold a stick in position just to keep the engine moving. On the 5 Channel, the 5th channel is just an on/off switch. That could probably be adapted for direction control, except there would be no neutral.

#6

Jon - I am not using the 4-channel radios for anything at the moment. I got them from a friend that used to use them for R/C planes.

#7

OK, thanks. I posted a link to this thread in the Live Steam forum. Perhaps someone will offer a clue.

#8

The rc live steamers that I had , Cheddar and Roundhouse , used the throtle on the left up / down , which remained where you placed it . And the fwd / rev was on the right stick , left / right , for direction , BUT the stick returned to the middle when released [ I think ]
Regardless , you can remove the centering springs from a stick , if you want it to remain in position , but just remove them for one function , either up/down , or rite /left .

I currently have 5 Spektrum DSM 2.4 radios , and they work GREAT .
In rc planes ,rc helicopters , rc trucks
Its also fantastic to attend a rc truck race at a track with maybe 60 people , and have NO frequency fears or someone on your frequency , ruining your day .
Only 10 or 12 race at a time on the track .

Read this about how to modify with pictures

http://www.rcgroups.com/forums/showthread.php?t=856318

#9

Thanks Dennis. I ordered the radio yesterday from Red Rocket Hobby Shop via eBay. $99 delivered. There is no price competition ion these things at all, the only place to get any deals is on shipping. I saved about $10.

The link you posted is exactly the part and procedure I used on my cheapo Futaba Attack transmitter.

#10

Aristo-Craft are also releasing a 2.4 system specifically designed for trains (no price announced as yet). However, do not act as devil’s advocate and question future availability of this new system, or the wrath of God will descend on you. There are some touchy people out there who do not like anyone to question any Aristo products. Hands up all those with the now defunct 75 mhz system. It seems that progress demands some financial sacrifice (not just the cost of a new system, but the redundant cost of the old system). Some see this as progress. I still use the 27mhz system, but am concerned that its future is also in doubt to support interest in the new 2.4 system.

#11

Assuming they have the same frequency;
Every RCS TX ever made will still work any of the current RX - ESC’s.
Like wise the current TX-24 will work any of the RX - ESC’s ever made.

That situation is not about to change.

#12

Tony,
the 75 mhz system was based on a specific chip manufactured by Daewoo (no longer produced). The new 2.4 system is based on a specific chip manufactured in Sweden by Chipcon(?). The product is no doubt up there with the best, but putting one’s eggs all in one basket is a little risky. Apparently, the reason the 27 mhz system is still around is that an alternative component supplier was located when original supplier was not available. There is simply no attempt at backwards compatability (hardly likely with a frequency change), but it is the enforced redundancy that yanks my chain. Some see this as progress.

#13
Tim Brien said:
Tony, the 75 mhz system was based on a specific chip manufactured by Daewoo (no longer produced). The new 2.4 system is based on a specific chip manufactured in Sweden by Chipcon(?). The product is no doubt up there with the best, but putting one's eggs all in one basket is a little risky. Apparently, the reason the 27 mhz system is still around is that an alternative component supplier was located when original supplier was not available. There is simply no attempt at backwards compatability (hardly likely with a frequency change), but it is the enforced redundancy that yanks my chain. Some see this as progress.
Actually, when Mr Polk announced the 75 Mhz system it was supposed to solve the "problems" of the 27 Mhz on board system. When the plebs started moaning about the imminent redundancy of the 27 Mhz system they were perfectly happy with, Mr Pollk promised to offer a 27 Mhz version of the plug in RF part so that the 75 Mhz hardware would be backwardly compatible with the older 27 Mhz TX's.

That “daughter” board was never produced.

Mr Polk has tried to take on the DCC market once before using his H0 RCC system with singularly spectacular results.

I have to hand it to him. To paraphrase Sir Humphrey Appleby in “Yes Minister”, this is a brave decision.

#14

The DX5e arrived today. The TX is very BIG, but not unusable. It’s about 20% bigger than my Futaba Attacak, but it doesn’t have the long antenna. I was pleasantly surprised with the size of the RX. It is tiny, and weighs nothing. Designed for sport flyers I’ll have no problem fitting it in the wood load on my Shay.

I still use several 27 MHz TE’s. One for my track power and another for my battery trail car. It’s an OK system and I have no range issues. I’ll wait and see what the new radio system actually looks like, costs and how it performs before I decide one way or the other. 2.4 GHz will get rid of the big antenna, but I’m not sure we need lots of bells and whistles. A couple of outputs, like Tony’s system, is about all that anyone needs.

Since your looking in here Tony… Now that I have this nice radio. What would I need to buy from you to use it to R/C one of my sparkies? I know I’d need another RX from Sperktrum.

#15

Jon.

Any of the EVO ESC’s depending on what sort of loco you wish to install it in, and whether or not you need constant brightness directional lighting and sound triggers with it.

The direction and speed control are on one stick and must be spring loaded back to the middle when you let it go.

You can actually have up to six sound function triggers if you wish.
Also, you could easily set up one stick to operate micro servos for uncoupling.

Mount the TX in a fibreglass cradle slung from your neck and waist and you could simulate the full size “Belt Pack” real life R/C controllers.

#16

Jon - You also now have the option of the G-Scale Graphics RailBoss R/C with automated station stops (controllable from the Tx).

[Out of courtesy, I let you answer first Tony :slight_smile: ]

#17

Thanks for both answers :smiley:

I won’t be investing in any more RR stuff in the near future. Just got told they are cutting my pay 20% starting Jan 1. As compensation, one day a week is “attendance optional”. I’ll bet you can guess which option I’ll be taking.

#18

After failing to get to my house two days in a row, FedEx home delivery finally arrived Sunday evening with my package. They promptly got their rental truck stuck in front of my house after dropping the package. No wonder it took them 3 days to get here from 20 miles away :smiley:

Anyway, I was pleasantly surprised by how small the RX unit is. About half the size of a match box or 1/3 of the Futaba 27MHz RX unit. It has two antennas that are supposed to be oriented at 90 degrees to each other in your “aircraft”. I think I might be able to get away with keeping the antenna completely hidden in the wood load which will be nice. For initial tests I have it in a 4" antenna tube sticking up from the load, but I think I can cut that way back.

Operation of my single HiTek micro servo is very smooth. I got all the components back inside the water tank last night and it looks like I can get quite a bit of travel on the Johnson Bar valve. There are 32 ratcheted steps on the throttle stick. This should be plenty for fine control of the Johnson Bar. Odd thing though, since I am using the Throttle stick, the digital trim only works at the bottom of the stick, not in the center where neutral will be. I also can’t get the fail-safe to go to neutral - it seems to be factory programmed to throttle off, which will be Full Reverse on my Johnson Bar.

So - I opened up the TX to see if I could modify the right stick (elevator) to ratchet and not spring center. It looks simple enough, but I will need to buy or make a ratchet pawl. I’m assuming that the Elevator stick is programmed to trim in the center and that I will be able to set the fail-safe to center or Neutral. Then, if I ever use this as a two servo set up (Throttle and Johnson Bar), the left stick will be Throttle and the right stick Direction. For now I am manually opening the throttle about 75% and using the Johnson bar to control both speed and direction.

Tonight we test under steam.

Update: Just read the manual again. I should be able to get the throttle stick to failsafe in any position I choose. I must have been screwing up on the binding procedure. The elevator stick failsafe (no RF signal at RX) is no output / no change, so for failsafe purposes I’ll stay with the throttle stick for now and not worry about trim unless finding neutral is a problem.

#19

Jon,
Take a look at the binding plug. Its just a servo plug that has a jumper wire on it. Binding plugs have a mind of their own and seem to wander off into the netherworld, so be careful where you put it. I always keep one right inside the battery compartment of the radio itself. That way its handy at the field if I need to rebind a receiver for some reason.
One note on the Spektrum receiver. I’m assuming you have something like a 6200 or 7000 since you mention it having two antennae that should be oriented at 90 degrees. This orientation and the twin antennae are particularly important in flying models. The orientation and redundant antennae keep the signal coming to the receiver from being blocked aircraft’s airframe, which is always changing in orientation. In model RR’ing we are generally working in 2 axis so it won’t be as critical and the model doesn’t change orientation as much so the 90 degree orientation isn’t as important. Just try to keep a clear path by putting the antenna or both antennae up high (i.e.:don’t bury it in the bottom of a tender or fuel tank on a diesel).
You’ll like the Spektrum and its freedom to operate in noisy environments. I also like the short transmitter and receiver antennae.
Dave

#20

Thanks Dave -

The receiver is an AR500. I can get the system to bind, but it doesn’t want to keep my failsafe throttle position at 50%. It always reverts to 0% throttle, which is full speed reverse in my application :o I’ve read and re-read the manual on both binding and failsafe. It seems like it should work, but it might be a limitation of the receiver. I wrote to Spektrum Tech Support, but just noticed on thier website a clarification of the bind procedure, so I’ll try one more time.

Test under steam went well. Once I got used to how little stick was needed to make it go, it seemed like I could get pretty reasonable speed control from the Johnson bar. My servo horn was pretty far off, so I set the radio to neutral and adjusted the horn. I should now get neutral close to stick center. 2nd steam test this afternoon if it stops raining.

My initial installation I had one antenna wire in a 4" tube sticking out of my wood load. I decided to experiment with a less noticeable antenna, so I cut the tube flush with the top of the wood load and now have about 1.5 inches of antenna peeking straight out of the load.

With this new smaller receiver I can almost cram everything into the water tank, but not quite.