Hi Guys

Right, I'm choosing a receiver for my smaragd freestyle, it's electric too and I'm wondering what futaba reciever to get.
Whether just a standard d/c or the pcm versions.
Your input is greatly appreciated

I use PCM to protect people on the ground. I had a TX failure that caused my plane to go off on its own. I use PCM to prevent this from happening again.

if its over 7kg, you need PCM anyway, dont think yours will be tho. But its safer to do that, as said above. I use nothin but PCM from my funtana, to my 44% Cap 232.

futaba 9ch pcm... cant beat them!

In my opinion there is no doubt, PCM is the only way to go especially if its a dual conversion PCM receiver like Futaba. You spend way to much money on these rigs to skimp $50 or so to go FM. I have seen the benefits of PCM several times over where FM guys are getting hit and crashing. I have yet to see a guy lose a plane, or even glitch, due to interference with a PCM reciever. In my opinion, there is really no logical reason NOT to go PCM other than cost on anything other than electric park flyers. On the other hand there are a lot of guys who never fly anything but FM and have never had a single problem....[sm=confused.gif]

I had been getting little radio "bumps" from time to time at our field. I had been using PPM since it came out and had been fighting off going to PCM. Made the switch to PCM a while back and haven't had any more "bumps".

It's also nice being able to set the servos to go to a given point in the event of signal loss. You know what the plane is going to do if it happens. Not so with PPM.

i was lucky i had a runaway too. i was in a valley and my plane flew strait and level into a stand of trees 30 feet up so i was able to recover the plane with little damage i bought the hitec eclipse 7 qpcm. i have futabas, jr and hitec. i like the hitec more than the other brands. i have 2 helicopters and a handfull of planes and i found the hitec to be the best at programing. the hitec has built in setups that run planes, helicopters and gliders.

so what does the failsafe do for you. i mean what do you set the plane to do in the event of a signal loss. obviously not fly strait i guess but what then?

sorry if this is a stupid question[&:]

Best as I have interpreted what I have read and seen with my own eyes,,,
a. if the plane momentarily loses the signal the PCM rx just holds the last good input and you never even see it.
b. If the rx loses the signal for about 6 seconds the controls go to the "failsafe" mode that you setup in the transmitter. I set my failsafe to idle and straight level flight. Lots of guys set failsafe to min throttle, and basically a snap-roll input so that if the signal is lost the plane just balls up and falls straight down. But remember this failsafe doesnt happen unless several seconds of signal loss elapse, if its just a few seconds the controls just hold their position where an FM rx will be jumping all over the place from the false signal.

From what I understand a PCM signal is basically a coded signal. The rx gets the signal from the transmitter in code, the rx decodes the signal and sends the signal to the servos. So if the signal coming in is on the right frequency but isnt the right code the rx ignores it and continues with the last good code. Dual conversion Futaba Rxs do the same thing but its more than 1 "code". That may not be the best technical description but its the general idea.

A plane will crash with a glitch way less than 5-6 seconds so an FM receiver that loses singal is doomed where a pcm may just overshoot a little. From what I understand,, seldom does real interference last that long so the PCM receiver maintains the last good signal and the pilot never even sees it. All I can tell you is that I havent ever seen or heard of a PCM rx lockout being the cause of a crash. Maybe PCM rx failure but few if any crashes due to interference.

pcm is the way to go. FM recievers will take any signal that is on their band and frequency. pcm is a digital square wave and if the signal does not fit, it will reject it. kind of like a change machine. it will accept only valid currency and anything else it will reject. it is very particular and wont give you any coins "unexpectedly" a change machine working like an fm receiver does would be like you stick a piece of paper, any kind, into it and it will give you something, but not necessarily coins. PCM is actually on the fm band but it is a square wave digital signal rather than an analog pulse.

there is a probleme with radio multiplex and motor gas !!!
parasite with ignition !!!

'need' is kind of strong wording. there is no legal requirement for any particular size, you could even use AM or 27 mhz if you really wanted to. lots of people use standard ppm rx's with large planes, and there are advantages to ppm also. (you actually see glitching, whereas a pcm is all or nothing)

5-6 seconds? which rx's take that long? my futaba 8 channel pcm takes a little over a second to to to FS.

There is a rule in the UK where if you are over 7kg you need PCM by law. If over 20 kg and you want to fly publicly you need an inpection at all stages of building and flight testing to pass. And of course PCM

You dotn need PCM, you need failsafe... might aswell use PCM thoug eh!! much easier and more reliable than a seperaste failsafe.

rkramer... agreed futaba tends to take 1-2 secs to initiate at most and abotu 2 seconds to come back in.

I woudlt mind PCM as my field is a crash hell. But thing is they are bloody expsensive! Any cheap good ones?

they are cheaper than new planes. they arent that expensive. if you have a transmitter that can broadcast in pcm than it will only cost you for the receiver. the futaba r138-dp is about $100 and that is a lot cheaper than a new plane and new components

Ok I see your point but I am poor and selling everything, have a little sympathy ok?

Ill get a budget PCM but i already have a D/C that I might use for a while.

richard, as i said, if youve spent 1000s of pounds on a plane, why skimp on a cheepo reciever? buy the best your wallet, and wife will alow

I have to agree, people spend $100's and $1000's of dollars on a plan but by cheap batteries and other accessories.

i wouldnt mid going out and spending about 30 quid on a battery, 20 on a switch if i were sure they were good quality, if either fail, say bye bye to your plane.

£20 switch? If I was worried about a switch id make my own with gold wire.

ok, 20 is OTT. but i wouldnt ever buy a cheepo one. what you save in the short term will make up in the long term

You may not believe this, but the ONLY time THINK I have had one of my Futaba R149DP's go to failsafe instantly was once when I had low voltage on my battery. And that was weird, the engine servo was the ONLY servo that went to failsafe . It would bounce back and forth from idle(failsafe setting) to wherever I had the throttle set. It was almost like a warning or something. But on approach with the plane within a hundred feet I had full throttle control again. I have never felt complete loss of control though, if Im getting hit I have never felt it with PCM, but I have felt it on the same channel at the same field with a ppm rx (Channel 53).

Does anyone know for SURE if what I am saying is true, will a Futaba 149DP put the throttle only to FS in case of low voltage to the rx?? I know it happened but I could be wrong as to the cause.. ??

that is an automatic function. all futaba pcm receivers will do that but on low battery only.

well, I'm going for a PCM receiver, there's no two ways about it for me. Been talking to someone who's plane did a flyaway, £4000 worth of plane, flew 4miles away, landed in a field with minimal damage to the plane. Police found it and was saved by the failsafe.

So I know what I'm doing, but don't stop posting, I'd still like to hear the pro's and cons.