[NSRCA-discussion] RX choices

[White, Chris]

I know that I've had range problems using PPM on certain ignition
setups, but PCM made the range problems go away....  I would guess there
are probably some variables in installation that make a difference....

Chris

 

________________________________

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Bob
Richards
Sent: Thursday, September 14, 2006 1:46 PM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] RX choices

 

Most of what I use PPM receivers for are sport models or small
electrics. Even then, I have decided to stay away from the single
conversion RXs, even on the ultralight foamies. I've had too many
glitches with the cheesy single conversion sets.

 

Having said that, there are advantages to some of the PPM receivers.
With proper filtering, it is possible for a PPM RX to continue operating
with certain interference that would render PCM inoperable. Not very
likely, but possible. I do know of one case where PCM radios were having
problems going into failsafe, but people flying PPM were not having
problems.  At one time (years ago) I was told that PCM did not work well
on planes with ignition engines. I never disputed it, though I never
have seen proof of it.

 

With PCM, you may not know that interference is present until it goes
into failsafe, then it may be too late. With PPM, you may get glitches,
but usually at least some control gets through.

 

I use the PCM RXs in my high-dollar planes, and have my failsafe set to
kill the engine.  For most planes, I leave all the other controls at the
last good signal position.

 

Bob R.



Wayne <Whinkle1024 at msn.com> wrote:

	I have a question guys.
	
	I see in lots of posts guys using FM (PPM) RX's. Why is this?
	
	In today's market there are so many choices of good PCM RX's I
can't 
	understand why someone would actually choose to run FM. Back in
the days 
	when I started RC there was no PCM and we had the choice of AM
or FM. I was 
	taught that my model was too important to me not to run the best
link 
	possible, at the time FM was it.
	
	When PCM came in the price was much higher and I can see a
reason to not use 
	it. Today however both Futaba and JR have PCM RX's that are good
for under 
	$99, JR now even has one that PLL Synth. So why use FM?
	
	It is my understanding with today's PCM that noise rejection is
so much 
	better with PCM that it seems along with its F/S properties both
model and 
	people are better protected. I can see the reasoning among
average modeler 
	its price why else do MPI, FMA and so on make such a profit on
off brand 
	leads and servos that are in my opinion very sub par. I felt
that in the 
	pattern community with available models shrinking, and the cost
of models 
	hitting larger prices that guys would trust their baby to better
equipment. 
	I mean a basic pattern model that is on the cheap is going to be
$1000 to 
	$1500 all up. The difference in a 127 Futaba RX and say a Futaba
138DP PCM 
	or JR 790 PCM version is about $40
	
	What am I missing?
	
	Wayne 
	
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