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Old Mar 04, 2013, 05:09 PM
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Receiver Polarity Question

I'm installing my first receiver. It's a Spektrum AR400.

How do I figure out polarirty of say, the servo connectors.?? The servo connector can be plugged into the receiver the wrong way OR the right way. Usually one can see the colored wires(brown, blue, red) but the receiver shows no "code colors."

Also, about these antennas. They can be taped inside the fuselage and still receive the signals, correct.?? It's odd because I sometimes see antennas fully exposed outside the fuselage, strung through the tail section or laying along the back of the fuselage. My Super Cub's antenna is inside the fuse but the underside has holes in it. The Dynam Cub that I'm putting together has a solid fuselage so I'm asking the question.... Antenna taped inside okay.??

Thanks in advance.
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Old Mar 04, 2013, 06:01 PM
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The Northeast Kingdom, Vermont
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Exactly what servos are those. By any chance are they older Airtronics servos??
If the red wire is not the center wire in the plug, do not attempt to use those servos, since the polarity is wrong, they can be modified by rewiring the plugs..
If the red wire is in the center, then the plug should be inserted with the brown wire to the edge of the case, which is the negative pin(s).
There should be symbols on the side of the case to indicate + - and signal, which is a depiction of a square wave pattern. On that receiver the row of pins away from the edge of the case are the signal pins. Signal wire on most servos is either yellow or white, and + is red and - is either black or brown.
Pete
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Old Mar 04, 2013, 06:32 PM
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Thanks Pete.

I just took a looksy and wow, that's some small type.

Okay, I see that that negative is outside edge and positive is middle. Now this.... Detrum Servos. 3 wire connectors are definately Red middle but the other 2 colors are hard to see. One is Brown(sort of orange, maybe slightly yellow) and the other is well, I can't explain the color...even with reading glasses.... sort of red, maybe brown, maybe green.?? Man, drives me nuts.!! Why can't they be contrasting colors.??

I hate it when simple things like this become confusing.

I'll take a picture and blow it up to see if that helps.
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Old Mar 04, 2013, 06:45 PM
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Okay Pete... Which wire is signal.?? (pictures came out great)(best idea i've had in a month).!!!
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Old Mar 04, 2013, 06:55 PM
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OK, great pictures! The wire on the left in the pic is definitely the signal lead, so it goes in just like your pictures show. Sometimes those yellow/red/brown colors are harder for guys with some degree of color blindness to see, than the white/red/black wires used by Futaba. I had a friend that was completely color blind, even he could deal with the signal wire being white and the negative being black. The JR colors, not so easy
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Old Mar 04, 2013, 06:57 PM
rfk
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I would go with brown wire (right) is the ground and the yellow/orange is the signal.
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Old Mar 04, 2013, 07:14 PM
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Beautiful. Thanks a lot.!!
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Old Mar 04, 2013, 10:41 PM
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Can anyone comment on my antenna question in the original post above.??

Does the antenna need to be external from the fuselage or is it okay to keep the antenna inside the foam fuselage.??
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Old Mar 05, 2013, 02:58 AM
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2.4GHz short antennas like that are fine within the fuselage. Foam and/or wood do not get in the way of radio signals.

BTW for future reference, you're more likely to find answers to your radio questions in the Radios forum http://www.rcgroups.com/radios-135/

Steve
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Old Mar 05, 2013, 08:47 AM
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Okay, thanks Steve.

I looked for a forum to pose my questions and must have missed it.
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