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JR 921 2.4 Receiver Mounting

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Old 02-23-2008, 04:50 PM
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Harleyflyer
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Default JR 921 2.4 Receiver Mounting

I am getting ready to mount my R921 2.4 receiver and have a question. I was thinking about mounting it in the center...near the bottom of where the canopy attaches......just a little behind the wingtube in my 35%er. My ignition and regulator are near the cowling some distance away but my 2600 Fromeco ignition battery is mounted just behind the wing tube so my main receiver would a few inches from it and above it.....does anyone think this would be a problem? Also, I am going to be using two satellite receivers and the second satellite will be as far back and low as I can get it....about 2 foot.

Thanks in advance.
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Old 02-23-2008, 08:31 PM
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Default RE: JR 921 2.4 Receiver Mounting

I wouldn't worry about it. I just installed the R921 with one remote(12" away) in an old style pattern airplane. The main receiver was sandwiched between a 2000mah 5-cell receiver battery forward and the servos/retract airvalve to the aft. On top of it was a metal tuned pipe and below it when the wing attaches are the two aileron servos and pushrods. The remote was place with the tuned pipe no more than an inch above and the dual elev/rudder metal pushrods right below it. The advanced range check numbers were good and the post flight Flight Log numbers were all good. With your two remotes a good distance away, I would not worry. Even my main receiver has few fades and there are no holds.
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Old 02-24-2008, 08:33 AM
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Default RE: JR 921 2.4 Receiver Mounting

Okay, thanks airbusdrvr, appreciate your response. I don't know if you or someone else might know but I did some testing with the Flight Log. I see the fades on the two antennas for the main receiver and the two for the primary satellite receiver. However, I do not see anything on the Flight Log screen that gives any information on the second satellite receiver I added. Does anyone know if I am doing something wrong or is the Flight Log just not set up to gather the data on the second satellite receiver?

Thanks.
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Old 02-24-2008, 08:55 AM
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Default RE: JR 921 2.4 Receiver Mounting

The main receiver unit actually counts as 2 receivers and each remote counts as one. So you should have 4 numbers with the main receiver(s) counting as 2 plus the 2 remotes.

Edited for really poor typing skills
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Old 02-24-2008, 10:06 AM
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Default RE: JR 921 2.4 Receiver Mounting

Look at page G-21 in your manual. As UAL767 states, the first two numbers(after the voltage, ie 6v4) are the two antennae on your main receiver, then the next line is the number for the "left" remote and the fourth number readout is for the "right" remote. There is only one number for each remote even though it has two antenna.
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Old 02-24-2008, 11:15 AM
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Default RE: JR 921 2.4 Receiver Mounting

While experimenting with the rx/antenna placements, I discovered that the main rx seemed to perform better if it wasn't real close to batteries.

The readings from the data logger were acceptable, but when I moved the batteries around while adjusting the CG, the readings from the data logger for the main rx got better. Being between two voltage regulators didn't seem to bother the main rx, but I did get more fades with it mounted close to the batteries.

That being said, I've got another model where I don't have a lot of choice but to mount the main rx close to the flight pack batteries and while I've not flown that model yet, the ground range checks are pefectly acceptable. I run two satellite rx's on my R921's with one going forward and one going aft. One of the satellites is near aluminum angle used to brace the gear area, the wing tube, exhaust cannister, etc. and those don't seem to affect the signal other than when the model is pointed directly at me (which also puts the engine between the tx and rx), then there is just a slight reduction in ground check range.

The data logger is a great tool and the first model I put the R921 in and did data readings relgiously helped assure me the system is solid, I don't even bother looking at the readings now except on rare occasion...
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Old 02-24-2008, 11:12 PM
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Default RE: JR 921 2.4 Receiver Mounting

This makes much more sense now.......I appreciate everyone's input!

Keith
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Old 06-05-2008, 04:25 AM
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Default RE: JR 921 2.4 Receiver Mounting

I have JR R921 receiver and its remote on my %30 YAK54 plane. I wanted to add 1 more remote to be in a more safe side and bought spectrum remote receiver. I have added the spectrum remote on my JR R921 and bind the system again. During binding all lights were blinking on receiver and its remote and spectrum remote as well but after the binding when I turned on the system only JR R 921 receiver and its remote light were on , nothing were on the spectrum remote.

Is that means there is no more lights on after the binding at spectrum remote receivers ??? and it works without any ligh???

Please explain
Thks
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Old 06-05-2008, 05:40 AM
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Default RE: JR 921 2.4 Receiver Mounting

tuavp, you should ask your question in a new post. It may not get noticed at the end of this one. I have both JR 921 and Spektrum receivers. I have never mixed them, but I have never heard or read that they are different. The spektrum should be interchangeable with JR. But ask your question in a new post and I'm sure someone who has used your JR/Spektrum mix can answer the question. Take care
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Old 06-05-2008, 08:26 AM
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Default RE: JR 921 2.4 Receiver Mounting

Yeah, a new thread might be best....

But I'll offer a thought; there are/were three different firmware versions for the rx's. The initial release, the first Quick Connect which all the R921's had, and the latest version of Quick Connect where the rx lights flash after a power brownout.

All of the rx's need to have the same firmware. It is quite possible that your Spektrum remote is not the same firmware version as the R921 and it's original satellite rx.

I run an R921 with a JR and a Spektrum satellite on two different models and it works fine.
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