DSMX Remote Receivers (Full Version)

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Handiman -> DSMX Remote Receivers (10/24/2012 9:50 PM)

Is it the direction of the antenna that have the biggest effect or does the body of the remote receiver have some influeance?
I am mounting a remote in the tail and I prefer to have the body laying flat.
Thanks for the input.



fizzwater2 -> RE: DSMX Remote Receivers (10/24/2012 10:06 PM)

bear in mind the two wires on the remote receiver are two halves of one antenna structure, they're not two separate antennas. They should stick out the sides of the case and point directly away from each other (straight out) for best performance.

Then, that antenna should be oriented 90 degrees from the antenna in the main RX.

You could always use one of the carbon fuse remote receivers, which has a long coaxial antenna - only the last 30-31mm of that is the actual antenna, and you could mount the receiver however it best fit, and keep the antenna oriented 90 degrees to the main RX antenna, which should be pretty easy to do with the long cable.




Handiman -> RE: DSMX Remote Receivers (10/25/2012 3:54 AM)

Thanks for the info. I want to put the receiver in the tail to help with weight distribution.
Thanks



Franco2fly -> RE: DSMX Remote Receivers (10/25/2012 11:27 AM)

Weight distribution?  That Sat rx doesn't weigh but a couple grams.  I put one antenna system in the horizontal plane, and the other in the vertical plane.  Use a penny in the tail if you need to move the CG back.

KKKKFL



Len Todd -> RE: DSMX Remote Receivers (10/25/2012 2:25 PM)

With any RF, if two communicating antennas (i.e. transmitter and one of the receiver antennas) become cross-polarized (i.e. out of phase by 90 degrees) ~ 50% of the signal strength is lost.  This is why we use multiple antennas. Also, IF ... The antenna elements on a remote receiver are only one antenna, then it would have to be a center-fed dipole antenna, which I am not so sure that is the case because two 1/4 waves oriented differently would work better to accomplish the multi-directional purpose. Anyway, ... Even on a receiver with one dipole antenna, orienting one element differently from the other still increases its ability to receive a signal w/o causing a mismatch. (Not always so on transmitters.) Consequently, on single receivers with two short antenna elements, I orient the antennas differently from each other to increase likelihood of maintaining the signal. I do this on all my helis. On my giant scale planes, I use AR 9210 receivers which have 3 remotes. Even then, I still have each element of each remote receiver's antennas oriented somewhat differently.

Regarding the weight, depending on the size of the craft, a remote itself may not change your CG by much. However, the wire harness has to be taken into consideration. I would put the craft on the CG balance, lay the harness and remote receiver out on the plane somewhat in position, then figure out if you want more weight. Again depending on the size of the craft and the desired CG, a penny could be too much. Once you have all the balancing done, fly the trimmed plane inverted. If she goes up, it is tail heavy. If she goes down, she is nose heavy. Decide if you have the CG you want and go from there.




Handiman -> RE: DSMX Remote Receivers (10/25/2012 6:34 PM)

Guys, I really do want to hear your ideas and experiences.
But I have a good understanding of the RF system and I am asking if anyone has seen a difference that the body of the receiver might effect the reception.
As far as the weight, yes I understand how little weight it is in the big picture. I am building the plane right now, I have a 2nd and possibly a 3rd receiver. I feel it will be better in the tail section, A- that part of the plane will hit the ground after the nose and wings have asorbed much of the impact so it is fairly protected from damage back there and it wont hurt me on the weight distribution matter.
I am using a 4 stroke motor so some tail weight will be a benefit. 
   Thanks



Aerocal -> RE: DSMX Remote Receivers (10/25/2012 6:59 PM)

About the only things I know of relating to the location of the body of a Rx having an effect on performance is when it is closely mounted near other electronics or in a way that allows vibration to be transferred into the Rx.I/C engines produce alot of vibration.Be sure that a Rx is not hard mounted to the fuse.Isolate vibrations with foam.Dont mount it right next to a servo,regulator or other electronics.

Actually back in the tail is generally a very good location.Unless there are servos in the tail it should be well away from any source of EMI.



chuckk2 -> RE: DSMX Remote Receivers (10/26/2012 6:45 AM)

With two remote RX's I mount one with vertical antennas, and the other horizontal usually in line with the fuselage.
If there is only one remote RX, it's mounted vertically, and the receiver (DX8 example) horizontally with the antenna at 90deg to the fuselage.



rickjeanuk -> RE: DSMX Remote Receivers (12/13/2012 4:08 PM)

I am mounting a AR7000 in my Radian Pro BNF. It appears the only room for it is on top of the esc which I fear may cause interference. I can get approx 1/4 in seperation by inserting a piece of foam between the rcvr and the esc. Is this acceptable? If I go by the length of the servo leads then it would mean cutting the fuse to get more room at this location. Mr. JR where did you mount the rcvr on your demonstrator?



AndyKunz -> RE: DSMX Remote Receivers (12/13/2012 7:50 PM)

Just cut out the foam to make room. My AR8000 is inside the battery hatch with some extra foam cut out.

Andy



BarracudaHockey -> RE: DSMX Remote Receivers (12/13/2012 8:14 PM)

Your reciever near the ESC likely won't cause any interfence.

Since it doesn't block RF, a piece of foam between the reciever and ESC wouldn't be any different than nothing being there (RF wise)



Len Todd -> RE: DSMX Remote Receivers (12/13/2012 8:38 PM)

You could test it and see if there is RF interference. I would do that by doing a FULL positional range check while running the motor at WOT. But, ...personally, I would do everything possible to keep the ESC from overheating. And I would think that having an RXer and foam on top of the ESC could easily cause your ESC to overheat prematurely fail. 

I would find and or make a better spot for the Rxer. 



chuckk2 -> RE: DSMX Remote Receivers (12/19/2012 9:17 AM)

I'd think of the question differently.

Will the remote RX circuit boards and case between the rf signal and the RX antennas?
Perhaps one or the other of the antennas, but not both at the same time would be my thinking.

I prefer to mount one of the remote RXs with vertical antennas as far away as possible from the servos, metal linkage, etc.
and to the rear rather than the front of the model.
The main RX is usually mounted with a short antenna horizontal, and 90deg from front to back of the models fuselage.
If the receiver has a longer antenna it's usually located at the bottom of the fuselage, and goes towards the rear.
One of my receivers has two short antennas, and I orient them 90 to each other.



Len Todd -> RE: DSMX Remote Receivers (12/19/2012 7:48 PM)


quote:

ORIGINAL: chuckk2

I'd think of the question differently.

Will the remote RX circuit boards and case between the rf signal and the RX antennas?
Perhaps one or the other of the antennas, but not both at the same time would be my thinking.
... 


chuckk2: I am not sure what you are trying to say in the above quote?

By the way, I mounted one of three remote Rxers with silicone sealant. Later I noticed that this Rxer was getting 3 to 4 times the number of fades as the other two remotes. I removed the Rxer and stuck it back on with servo tape. Now the fades are always about the same as the other Rxers. Theoretically, silicone should not bother the Rxer. However, I think the silicone sealant may have been causing some sort of a problem even though the antennas were sticking out past the case, etc



chuckk2 -> RE: DSMX Remote Receivers (12/25/2012 8:20 AM)

Makes you wonder what's in the sealant.

Now that I think about it, some of the car radar detectors use clear plastic as lenses and horns to direct RF to the detector.




BuschBarber -> RE: DSMX Remote Receivers (12/25/2012 10:54 AM)


quote:

ORIGINAL: Len Todd


quote:

ORIGINAL: chuckk2

I'd think of the question differently.

Will the remote RX circuit boards and case between the rf signal and the RX antennas?
Perhaps one or the other of the antennas, but not both at the same time would be my thinking.
... 


chuckk2: I am not sure what you are trying to say in the above quote?

By the way, I mounted one of three remote Rxers with silicone sealant. Later I noticed that this Rxer was getting 3 to 4 times the number of fades as the other two remotes. I removed the Rxer and stuck it back on with servo tape. Now the fades are always about the same as the other Rxers. Theoretically, silicone should not bother the Rxer. However, I think the silicone sealant may have been causing some sort of a problem even though the antennas were sticking out past the case, etc


Velcro has been more than adequate to mount 2.4 Rx's and Satellites. Easier to remove for service, as well.



chuckk2 -> RE: DSMX Remote Receivers (12/31/2012 10:51 PM)


quote:

ORIGINAL: BuschBarber


quote:

ORIGINAL: Len Todd


quote:

ORIGINAL: chuckk2

I'd think of the question differently.

Will the remote RX circuit boards and case between the rf signal and the RX antennas?
Perhaps one or the other of the antennas, but not both at the same time would be my thinking.
... 


chuckk2: I am not sure what you are trying to say in the above quote?

By the way, I mounted one of three remote Rxers with silicone sealant. Later I noticed that this Rxer was getting 3 to 4 times the number of fades as the other two remotes. I removed the Rxer and stuck it back on with servo tape. Now the fades are always about the same as the other Rxers. Theoretically, silicone should not bother the Rxer. However, I think the silicone sealant may have been causing some sort of a problem even though the antennas were sticking out past the case, etc


Velcro has been more than adequate to mount 2.4 Rx's and Satellites. Easier to remove for service, as well.


(I forgot to type a tiny little word or two)
Will the remote RX circuit boards and case be in between the RF signal and the RX antennas?
Perhaps one or the other of the antennas, but not both at the same time would be my thinking.
...

Actually, I prefer foam servo tape.




Len Todd -> RE: DSMX Remote Receivers (1/1/2013 3:07 AM)

The antennas stick out beyond the case. The case is plastic and will not affect RF. The circuit board and components inside could have an impact. But that is why the antennas stick out away from the board.



chuckk2 -> RE: DSMX Remote Receivers (1/21/2013 8:42 AM)

"The case is plastic and will not affect RF"

Maybe, maybe not!
Several of the automotive radar detectors use clear plastic RF lenses in front of and in metal wave guides. The lenses tend to improve sensitivity to the sides, and broaden the bandwidth.
As I remember, the air to plastic transition and the shape of the plastic surfaces are significant.



Len Todd -> RE: DSMX Remote Receivers (1/21/2013 3:37 PM)

The DSMX Remote Rxer's antenna(s) are outside the plastic case. All the radar detectors I have seen and have owned had internal antenns. The case on a DSMX remote Rxer itself is irrelevant.

What you put by the Rxer and how it is orienteted can make a difference. That is why once you mount a remote Rxer you need to examine your flight log data a few times to see if the Rxer is recording a significant number of fades. If you have more than one Rxer, then you can compare fades to see if there is a significant difference in the number of fades recorded on any particular Rxer. If there is a significant increase in the number of fades between Rxers, then you got a problem with its location and/or orientation.



chuckk2 -> RE: DSMX Remote Receivers (1/22/2013 5:11 AM)

I generally mount a single remote receiver with the antennas vertical.  the main receiver has horizontal antenna(s) at 90 deg to the direction of flight.
The TX antenna is generally horizontal. (DX-8), and in line with the TX case.  So far, so good. few frames recorded, etc. no holds.
I also like to mount the receivers as far away from such things as speed controls as possible. The remote RX is usually mounted as high as possible. In my 40 size P51, i cut a slot in the cockpit area behind the pilot, so that the top of remote RX sticks up into the cockpit, sort of where the scale location of the original radios was.  The main RX is mounted under the middle of the cockpit, with the short antenna sticking through the side.
(DX 8000 RX)



Aerocal -> RE: DSMX Remote Receivers (1/22/2013 6:12 AM)


quote:

ORIGINAL: Len Todd


quote:

ORIGINAL: chuckk2

I'd think of the question differently.

Will the remote RX circuit boards and case between the rf signal and the RX antennas?
Perhaps one or the other of the antennas, but not both at the same time would be my thinking.
... 


chuckk2: I am not sure what you are trying to say in the above quote?

By the way, I mounted one of three remote Rxers with silicone sealant. Later I noticed that this Rxer was getting 3 to 4 times the number of fades as the other two remotes. I removed the Rxer and stuck it back on with servo tape. Now the fades are always about the same as the other Rxers. Theoretically, silicone should not bother the Rxer. However, I think the silicone sealant may have been causing some sort of a problem even though the antennas were sticking out past the case, etc



It probably wasnt so much the silicone itself as it may be the lack of vibration dampening.Though it may be rubber its still pretty efficient at transferring vibration from the airframe directly into the Rx.



Len Todd -> RE: DSMX Remote Receivers (1/22/2013 7:36 PM)

I would think the servo tape I used to cure the problem would have transferred more vibration than silicone sealant. ??? 



Aerocal -> RE: DSMX Remote Receivers (1/22/2013 9:52 PM)

I tend to do alot of thinking also.Many times it leads me to the wrong conclusion.Servo tape doesnt seem to be very pliable in itself but I kind of think it does have some measure of vibration dampening.Now Im thinking again.I might be completely wrong too.:) Ive played with alot of gyros and that will raise alot of questions about vibration dampening that dont seem to follow basic logic at first glance.Sometimes its more of an art than a science.
For SPM 2.4 Rxs Ive generally used a foam type tape or velcro and never had a problem.A few I have just wrapped in foam and strapped down like we used to do with 72 Rxs.Sometimes its not the amount of dampening as it is the type of dampening in relation to the frequency or amplitude of the vibration.Every machine vibrates differently.What works on one may not work on another and vice versa.



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