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| 2.4 Ghz Spread Spectrum Technology Discuss Spektrum, Futaba FASST, and all of the exciting 2.4 transmitter/receiver technology here! |
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| | #529 (permalink) |
| Doo It! Doo It! ![]() | In my experience, the difference lies with the servos and not the receiver. The receiver does not output a pulse at all when turned on, but waits until it connects with the transmitter. I always get a movement with analog servos, both Futaba and other brands, but never see it with digitals of any brand. I have also experienced this with XPS and Spektrum/JR. With Futaba and XPS the servos will stay off center until the receiver and transmitter make connection. With Spektrum/JR, you might not notice it as much because the receiver starts sending the bound servo positions as soon as it boots up. If the servo moves quite a bit when first turned on, you will see it jump and then almost immediately go back to the bound position. With retracts it can be just enough movement to unlock the mechanism and let the aircraft fall. To avoid this, use all digital servos. Later; D.W. |
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| | #530 (permalink) |
| Gettin' Lower! ![]() | I have never seen it with Futaba PCM, (analogue servo's) i believe this is becasue the rx does not output any movement of the servos untill it get a recognised signal (a bit like failsafe hold). I have seen it in earlier PPM system. Paul |
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| | #532 (permalink) | ||||||||||||||||||
| Recovering Shankboner ![]() |
Yes I mean no, ok yes. Dave
__________________ Sadly sponsored by Visa, MasterCard, and Bank of America. | ||||||||||||||||||
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| | #533 (permalink) |
| Bad-ass Super Contributer! ![]() | The sun was shinning finally here in Oregon and temperatures soared to the high 70's and after all this I was very interested to see what temps were in my plane. When I first started putting my 35% Yak together the temp of the receiver case was 72F, by the time I got the wing tube in, both wings on and bolted down and the servos plugged in the temp of the black receiver case, exposed to direct sunlight, had increased to just over a 100F and the surrounding structure was still in the low 70's. My canopy has a floor but the receiver is mounted up high right underneath. I covered the canopy area with a large white towel when the plane was just setting arround. Flew several times with no problems. When I took the plane apart after about four hours the temp of the receiver case was 89. Just messing around we took the temperature of the skin of the airplane while sitting out in the sun. Areas covered in white were 88 - 89, red was 94 - 96 and areas covered in black were 129-130F. Ambient was about 75F when we did this. Diamond Dave I think you have that Yellow and Black Yak and that black covering may be causing a lot of your heat issues inside the plane. I think protecting a receiver from direct sunlight and routine care during hot conditions (I know 75 isn't hot) will probably eliminate heat issues. Bill |
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| | #534 (permalink) | ||||||||||||||||||
| Super Contributer ![]() |
Before a packet is sent, a preample is sent. In the middle of the preamble, the switch switches to the other antenna. After the preampble has been sent, the data recieved by the 2 antennas is compared, and the switch selects the antenna with the best reception. By this antenna, the data packet, which contains the control information, will be recieved. So basically, the 2 antenna approach offers the same benefits of the 2 reciever approach, concerning diversity. Both systems are able to recieve signals at 2 different locations, and both are able to determine which location is best for a given packet. Cheers, Julez PS: Drop me a PM if you need the exact patent script. | ||||||||||||||||||
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| | #536 (permalink) |
| Doo It! Doo It! ![]() | I have been an electronics tech for many, MANY years and learned a long time ago that heat is an enemy of electronic circuitry. If I had an aircraft whose innards were reaching 160 degrees I would do something about it regardless of any problems it might or might not be causing. Not saying that Futaba shouldn't look into this, but it seems that some kind of venting or shading is definitely called for with anything reaching these temperature extremes. My electric powered 1/4 scalers have internal batteries that reach around 130 degrees at times. With proper air flow through the fuselage, this has never been a problem. Looks like you wet power guys need to pay attention to us electric heads and learn a few cooling techniques. Later; D.W. |
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| | #537 (permalink) |
| Bad-ass Super Contributer! ![]() | I know there is probably a lot of useful info in here, and d_wheel, I am sure you are right that heat is the enemy of electronics. But the bottom line is that other manufacturers aren't having this problem, and as far as I know, Futaba receivers used to not have this problem. Now there is a problem, and it is unreasonable to ask the end user to make sure they properly ventilate their receivers to avoid thermal shutdown - period, plain and simple, end of conversation. Futaba needs to address this, and they need to start doing so YESTERDAY!. |
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| | #538 (permalink) |
| Bad-ass Super Contributer! ![]() | Well, the good news is that maybe it's a pretty contained problem. There doesn't seem to be planes falling out of the air at Joe Nall (at least not because of the heat issue :^) It looks like there has only been a couple of lost planes there so far (ate by trees?) |
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| | #539 (permalink) |
| Flyin' Around ![]() | Can anyone at Joe Nall report on the termperatires at the event? Also, maybe a poll of the FASST pilots who are successfully flying at this event to find out what they have done to assure their receivers are not over heating, if any? I would like to see some positive information to help us +25 year Futaba pilots past this problem. I fly in Arizona so right now I am grounded to to be save and have done testing like many others with the exact same results. I am also looking at ways of avoiding this problem and will report any information obtained. ![]() |
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| | #540 (permalink) |
| Super Contributer ![]() | there wont be any problem if you dont burn your RX in the sun... keep it cold like puttying a towel over the canopy. and if you have enough Air in and outtake in your fuselage nothing will happen. i dont know why knobody made this "trouble" by 35MHZ 72MHZ and so on... ic specs havent changed much ![]() well, even in my Delro XXL Raven (3,1meters span) with open resos/pipes in the fuselage i dont have probs at the hottest temps with the 6014 Fasst. -correct airflow in the fuselage, sure. regards, Chris |
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