Last I looked, JR RX's have no more current-carrying ability than the next brand (buss traces looked to be no more than 0.100" 1/2oz copper pour - dble-sided) RX. THere certainly is a bit of a misnomer out there just how much current one can safely put through a typical reciever, more than most installations could muster I suggest...
John Derstine wrote:
Simon: OF course, that goes without saying. Range testing is what is all about, degraded range is one of the problems associated with the use of dual rxs, cheap after market rxs, internal antenna routing, extraneous RF from motors, etc. The various problems can raise their ugly head when least expected. Especially when using after market gear. (Not saying that I don't use some, just careful what and where) I have a rigorous range test that I do every time I fly, probably one of the few pilots who does this. If I get a +10% reduction in range from previous checks or motor on motor off in the case of a power plane, I don't fly until it is resolved. The "hope" mentioned comes from spending all that extra effort only to find out through range testing that your system is performing less than expected. But I do understand people do it, and like the idea of it for whatever reasons make them raise their comfort level.
That said, to properly and easily check range with a pcm radio, I take
the antenna off, set the failsafe to deflect the rudder max throw, turn
on and start walking. I walk until the rudder kicks, record the
distance. If I get 100 paces I am confident, often I have to walk
farther than I can see the rudder on a big plane.
One of the other reasons guys started using dual rxs was to distribute
the load from large batteries, not as redundant devices alone. What has
been discovered is that this not necessary with some of today's
equipment.
JR has tested their 10 channel PCM rxs to destruction and found they
will sustain a very substantial amp load. I can't say exactly due to
product liability issues, but it is profoundly more than any combination
of servos and batteries can deliver, much more. The last big plane I built was a Hangar 9 46% Ultimate. One PCM RX, four
batteries (2600 nimh), one Matchbox (one battery to it for the 3 8611
rudder servos), a simple electronic battery backer and that's it. No
power management systems, no dual rxs. OH yea, an optical kill switch.
In any event, the RX is one of the statistically least likely components
to fail.
I think from my conversations with many pilots, the trend is getting away from using two rxs in large aerobatic planes. It just adds more complexity and more points of potential failure. It makes great marketing to make pilots think they need all those power management systems, and gizmos in their planes. It is somewhat intriguing to consider having multiple mini rxs spread around you large scale sailplane as cascaded systems, but given that they are basically micro hand launch rxs kind of limits the appeal. Not sure I would want to run 4 8611 servos through one on 3000 mah. Great for smaller sailplanes and for those wanting synth capabilities perhaps.
JD
-----Original Message----- From: Simon Van Leeuwen [mailto:[EMAIL PROTECTED] Sent: Saturday, March 26, 2005 2:26 AM To: John Derstine Cc: [EMAIL PROTECTED]; 'Dave Register'; [email protected];
'Gordy
Stahl'; 'Barry Kennedy' Subject: Re: [RCSE] Re: Soaring V1 #5375 - Shadow 3
No "hopes" required John...rigorous range testing will show whether there is any shortcomings when operating multiple RX's. It's as simple as operating one RX at a time under similar test conditions I just eluded to, then the other RX, then both simultaneously. If there are issues...they will show.
I forgot to add in my previous post a very important detail, when attempting to tune a RX antenna, or look for "any" anomolies it pays
to
have some sort of a baseline.
To achieve this requires setting the RX up as if it was in an aircraft that has no RF issues (like carbon). What you want is to determine how many feet you can achieve under ideal conditions. With this
information,
deciding what you will accept as a result of degradation due to things like carbon become much clearer....
-- Simon Van Leeuwen RADIUS SYSTEMS PnP SYSTEMS - The E-Harness of Choice Cogito Ergo Zooom
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