OK...

I got a couple radios.

Futaba 4EXA: I bought this new for my LT40. I wish I had waited.. But that's another story.

Futaba 6EX-PCM: (I think that's the official name) I bought it used, barely used, from a guy who wrongly thought it could fly his heli.

Anyway, Recent mods on my LT40 have leaned me towards using the 6 channel system. (Flaperons) I started looking through the manual to set up the flaperons, and ran across "PCM" and "PPM." I had seen these terms before, but hadn't taken them seriously because I had no immediate use for this radio.

I've got an inkling on what they might mean, but I'll keep my mouth shut. Don't want to say something totally off-base.

So.. What do these terms mean? How do they effect my setup? Going forward, when I buy additional flight packs will it impact that?

Maybe they're naive questions.. but I "just don't know" the answers.



Thanks in advance,

Lyndon

These refer to the methods of "modulating" or "encoding" the information on the RF carrier from your tranmitter. PCM is a little better BUT the good news is that your PCM transmitter can be set to transmit on the cheaper PPM system and you can buy the less expensive PPM recievers if you wish. Just read you manual and it tells you how to make the change.

Wait, how can this radio not control his heli? If he makes it so the throttle doesnt click, then isnt it the same. Maybe the placement of hte switches is different, but dont they all have the same programming?

Futaba makes a seperate airplane and helicopter version of the 6EXAS. The helicopter version has the programming features for things like idle-up mode and throttle and pitch curves, the airplane version does not.

The older 6XEA will do both acro and heli as well as PPM / PCM. I don't klnow about the 6EX version but if you changed from PPM to PCM, it wiped the model memory . You couldn't configure 1 model on PPM and another PCM. PPM is somewhat cleaner, and it won't glitch ... instead of glitching, it just stops responding until it receives an clean set of instructions. You can configure a failsafe on most receivers, but then instead of glitching, you can sit and watch it fly off into the sunset ...

So I can buy other receivers other than Futaba branded ones???

I kinda gathered that as I've been reading up on this stuff the last couple weeks, just didn't know for sure.

Would it be in my best interest to stick with Futabas? I mean, if PCM "encoding" is a bit better, wouldn't it make sense to spend the extra $20-$30 on a PCM capable receiver.. just for the added safety factor?

The receiver included in this package is, if memory serves, "FP-R127DF". If I read Tower's site correctly, it looks like this has been superceded by "FP-R168DF" Does that make sense?

The frequency on my 6EXA is channel 11. What's this I read about "lo band" and "high band" It looks like the receiver is the same for both, I merely need to buy another channel 11 crystal.


I know this is getting a bit off topic... But I want to make sure I buy the right hardware for the second, third, plane...

The RX's you listed are both FM PPM RX's. The R127DF is sensitive to the Hi/Lo issue in that it can not have a opposite end-of-band crystal placed in it without retuning. The new R168DF does NOT have this issue. It can use any crystal (72 MHz) without retuning.
The PCM is slightly better. Is it safer? That is a debatable issue IMO. Is a plane in PCM failsafe lockup that is flying away really safer? The ONLY advantage I see is that you can program the throttle to go to idle in failsafe. You still won't have control though and it may still crash.

Ch 11-35 are lo band and 36-60 are hi band. As long as your RX is anywhere in the same band all you need to do is swap crystals. DO NOT swap crystals in your TX unless you have it retuned - PERIOD.

You can use other brands of FM/PPM receivers with your 6EXAS transmitter so long as they are 72Mhz and support negative shift. Tower Hobbies and Hobbico branded receivers are simply "house brand" Futaba receivers, but are slightly less expensive. Hitec receivers are often shift selectable and will work with your Futaba 6EXAS, they just lowered their prices on their most popular models. The JR R600 receiver is even shift selectable, but most other JR receivers aren't. You will also find micro receivers for park flyers from GWS, Berg, and other companies that are either shift selectable or negative shift designs for Futaba transmitters.

PCM receivers are a completely different kettle of fish. PCM technology is proprietary from manufacturer to manufacturer. Only Hitec QPCM receivers work with Hitec QPCM transmitters, only Airtronics PCM receivers work with Airtronics PCM-capable transmitters, and only Futaba PCM receivers will work with your Futaba PCM-capable transmitter. The R138DP receiver is a nice little unit available in high/low band versions. It is soon to be replaced by the new R168DP PCM receiver that, like its FM counterpart, won't require seperate high/low band versions.

The bottom line is that there a plenty of great receivers out there that are compatible with your Futaba transmitter. I've run Hitec and GWS receivers on a number of my planes and they perform every bit as well as my Futaba receivers. For PCM mode though, you can only use Futaba.