What receiver should I use?

[Laury415]

I have a X10s radio and use mostly basic functions. I've been using FrSky products for many years (previously with an X9d radio). I've mostly used the X8R receivers, but over the last few years I've been flying more gas engines with electronic ignition. Some of my planes are 60 size with gas Evo engines, or 20cc size with DLE gas engines, and I also have a large 3d 30% plane with a 3W 100cc gas engine. I've never had any problems with the X8R receivers, but I do get low signal warnings at the edges of our flying area. I've had a few unexplained crashes but can't say they were caused by radio issues.

With my larger and more expensive planes, and newer receiver products available I'm interested in understanding what might be the best receiver solution/s for me. Like I said I do basic things for fixed wing planes. I have some mixes for flaps, I use curves for throttle, and generally run all servos on separate channels (I.E. my big plane has 2 servos/aileron and I run each servo on its own channel) when there are 2 elevator servos they each get a channel, throttle = 1 channel, opto engine kill switch has a channel, choke has a channel, flaps each have a channel, and retracts (where applicable) have a channel. My most complicated plane used 11 servo channels which is accomplished with an X8R and an SBus decoder (4-channel)

Is the X8R still a could solution? is there a better receiver seeing I've read electronic ignition can cause FrSky issues? Should I run redundancy receivers for extra safety? Should I use the RB-10 or RB-20 when I need more then 8 channels? Are Stabilized receivers something I should think about and if yes can I still keep the servos on separate channels.

Thanks for any suggestions

 

[Konrad]

If running ignition engines the new firmware and hardware found in the X8R-pro really is all you need. These also have redundancy capabilities A real nice feature! I have no idea why the X8R is still marketed.

FrSky RX8R PRO

An upgraded version based on the RX8R receiver, it has all the same features including redundancy. The Pro version has higher precision and lower latency. It’s deviation of PWM is reduced to 0.5us, and the delay of PWM output is 9ms less than that of the

alofthobbies.com

I'd avoid the stabilized RX. These are the highest cause of FrSky issues. Not because they are faulty but rather the set up and programing is so counter intuitive. It takes a very systematic approach to setting these up.

I'm replacing all my X8Rs with the X8R-pro as I revamp the aircraft for a new season of flying.
(FYI: I don't fly ignition ship. I just like the added security)

I'd look into the RB-20 for power distribution if using so many servos. The standard RX radio bus bar and connector (Jr style) are really only good for 5 to 7 amps.

All the best,
Konrad
P.S.
This makes a real good redundant RX.

FrSky XM+ - Micro SBUS Full Range Receiver

This is the XM+. Teeny tiny and weighs just 1.5 grams. It is an excellent choice for building a micro quad. The XM can be soldered into your flight controllers wiring harness or you can solder on the included header pins so that you can connect to your fl

alofthobbies.com

 

[Laury415]

Hi Konrad,

Thanks for your quick response. Sorry its been a couple days for my reply. Sounds like the RX8R pro will be a good all around receiver for my needs. I'll probably repurpose my X8Rs to my cheaper foamies. I'll also buy the XM+ Micros for redundant receivers. If I understand correctly I would solder the connector on, then connect the Sbus on the XM+ to the Sbus IN on the RX8R receiver. I'm assuming the Sbus out on the RX8R receiver can still be used for the extra channels.

As far as amperage draw, it looks like each servo is pulling about 100ma. So 10 servos would only be 1A. Am I misunderstanding something? If not I should be well within the amperage rating for this receiver.

Thanks again,

Laury

 

[Konrad]

Yes to the XM+ and how S-bus can be used. There is nothing wrong with the RX8R no need to religate them the cheap foamies, but they'd work well in that application.

I think you are measuring the idle current. You need to measue the current with the servos under load. That is with air going over the flight surfaces.

 

[Dennis]

Hi
just read your post i have the same TX what i do every time before i fly a plane i put the radio in range test mode with 10 TX it's real easy to see what the range it displayed on the radio screen I am running the X8R and other frysky RX with and with out telemetry so far using this method i have not had a problem running Gas, Glow or Electric power

 

[Laury415]

I just got my RXR8 pro, with the XM+ for a satellite. I connected the XM + to the sbus as discussed in a previous post. I was able to bind the RXR8 with no problem, however I noticed on the XM+ the red light is flashing like it is trying to bind but doesn't do anything else. Is this correct? Is there any extra binding that's needed for the satellite?

 

[Skye]

There is a bind button on the xm and you must use it.

 

[Laury415]

I can only press 1 bind button at at time. Would the order be:
1) Power off, press bind on RXR8, power on, bind RXR8
2) Power off, press bind on XM+, power on, bind XM+
If yes, wouldn't the radio only bind with the last receiver?

Otherwise if both bind buttons need to be pressed when power is supplied I guess I can do it with the help of another person.

Would 2 receivers bind at the same time?

 

[Skye]

Inverse order. No, they don’t bind at the same time (unless you or a pal press both bind buttons at the same time) and yes, each must be separately bound. If there is an order, I’ve never followed it. Use the normal routine for each, either connected or disconnected. Yes, that means doing the same thing twice, and each will remain bound unless you or someone presses the bind button on both!

 

[Wayne]

You can have as many receivers bound to the transmitter as you like. There is no limit to this. There is no magical order or anything else. You could leave the transmitter in bind mode, and just keep adding receiver if you like.

Personally, I like to start with the receiver, get it into bind mode first, then put the transmitter into bind mode. This way I can observe the LEDs and see that the bind process occur.

 

[Laury415]

Thanks for all the help. I was able to get both the receiver and the satellite receiver to bind. I forgot to do a range check but while flying I went pretty far and had no issues with low signal so all is good.

 

[Wayne]

 

[Skye]

Have fun! My only quarrel with Frsky is the lack of thorough instructions.

 

[Laury415]

Finally got to run the RXR8 pro, with the XM+ in my 1/3 scale Edge 540. Unfortunately I wasn't happy with the results. Everything bound ok and appeared to be running but after a few minutes in the air I got a couple scary twitches so I immediately landed. On the ground I started testing by quickly fluttering the control surfaces (especially the Ailerons with the 4 high torque servos). Sure enough I was able to reproduce the issue which is an RX battery voltage drop, then what I assume is a brown out in which the control surfaces lock for a second before resuming operation.

When I got the plane home I tried all different set ups with batteries (LIPO & LIFE), & a BEC with the same lock up results. I tried with the XM+ connected, and not connected. Everytime I was able to get it to lock up. Some set ups took longer for the lock up to occur. I took the RXR8 pro, with the XM+ out and reinstalled the original XR8 receiver, and problem gone. I could not get the lock out to occur even as the battery/batteries dropped to 4.5V. I purchased several RXR8 pro, with the XM+ receivers and tried a brand new combo but again got the lock out.

In an earlier reply Konrad mentioned the RB-20 for power distribution because of the 8 servos I'm using. Is the RB-20 my best option? I'm assuming I would use the RB-20 with the RXR8 pro, and XM+ combo? Will the RB-20 work with 2) 2s LiFe (6.6V) which is what I currently have or is something else recommended? Why is this happening with the RXR8 pro/XM+ receivers but not with the XR8?

 

[Skye]

I feel your pain. I just tossed one away for scaring my donkey!

 

[Konrad]

Laury, I think you have demonstrated that the issue is with the pro and/or the XM+ Rx. While i think the RB-20 is a good solution to the power distribution problem. I think you have a more fundamental RF problem. I'd reload the firmware for the Rx's. And if the problem remains I'd return the RX to Fr Sky for repair or analysis.

 

[Wayne]

Laury - Can we get a picture of the setup you are using? Something is odd here. The receiver draw will be tiny, so should not contribute to this sort of issue. Where is the power coming into the receiver, and what is supplying that power? What is the estimated amp load?

 

[Laury415]

I've attached a sketch with my normal Power setup. It includes the batteries that I normally use. In addition to this setup I tried eliminating the Batshare, by using one battery, I also tried using two batteries with a Y configuration so they were in parallel (4400mah), and I also tried using 4 cell 3000mah lipo with a Castle BEC to provide a constant 6 volts with a max rating of 10amps. Results were the same with each configuration.

The ailerons have 2) Savox SC-1256 high torque servos/aileron installed (4 servos total for ailerons). The elevator uses 2) of the same Savox SC-1256 servos. I couldn't find power draw information for the servos, but I was able to put a watt/amp meter inline when the lipo-BEC was used. It was pulling less the 2amps.

 

[Konrad]

You are driving the RX through the S-port (smart port) not S-bus?

This 2 amps on the bench measured with a dampened meter (RMS) not peak. But even without air loads the RX browned out. Have you tried to drive the RX directly through the PWM servo bus?

I don't think S-port was meant to be a power bus (drive servos).
S-Bus yes. But not S-port.

 

[Laury415]

Yes providing power to the Smart Port, it's the only port I have available. I'm using channels 1-8 for servos, S-Bus In for the XM+ satellite receiver, and S-Bus out for a 9th channel through an SBus converter for the ignition opto switch.