Hallo, I'm writing from Italy. I reached this forum in search for solution to my problem.
I have a Taranis X9D+ binded with a RX8RPRO in a 3m electric glider that I was before flying with a RX8R and never had a problem.
The first time I've flown the glider with the new receiver, after the climb I got telemetry and signal lost: the glider banked hard as if an aileron got fully deflected; then, in a matter of seconds, I got telemetry and signal back for few seconds and then lost both again and so on till the ground.
I have a Castel Creation Phoenix Edge 100A that has a 5A BEC inbuilt. The glider is equipped with 4 Hitec 125MG in the wing + 2 mini servo.
I tried to replicate the problem on the ground and I found that, by moving all the servo at the same time, I was able to do it.
I replicated this test with the RX8R I was using before on the glider and it was all working fine.
Then I tried to use NiCd / NiMh battery pack (both 5 elements), using a voltimeter between the battery pack and the receiver and logging the results of the telemetry.
This is what I discovered. The RX8RPRO switch off (red led) with lost telemetry and signal lost as soon as the Voltage drops below 4,8V.
The RX8R instead keeps working well below this voltage.
Looking at the specs. both receivers are rated for a voltage between 3,5V and 10,0V.
So, the reason of my crash is that my Phoenix Edge ESC was feeding 5V and, with all the servos moving, the voltage dropped below the critical 4,8V and the RX8RPRO stopped working. By stopping, the voltage of the BEC went up again to 5V and the receiver woke up again: at this point I had the sticks all the way on one side to recover the glider, so again: full servo load, voltage below 4,8V and the flying circus went on this way till the ground.
Attached you can see a test LOG I've recorded using a 5cell NiCd battery pack. The first run is with the PRO, the second with the standard RX8R. I tested the PRO before to put it in the best condition (battery almost fully charged).
Hello
I had a similar problem. RX8R pro is very sensitive to low voltage.
You will need a minimum of 5 cells accu or better 2S Lipo. Have a look at the telemetrie data of the RX-Batterie Voltage.
4 cells NiMh or even 6V voltage regulator are to low for a save connection.
The more servo load you get the worse it will be.
I returned my RX to the German dealer and he and Frsky confirmed after measurements, that all Rx8R pro in stock behave the same way
and that they don't hold a steady connection with a 6V laboratory power supply.
This is caused by the Strong anti-interference performance.
The dealer is going to replace it with a Archer R8 pro as soon as it is available.
The predecessor RX8 and the next generation Archer R8 should be better (says Frsky).
I was told by my dealer that Frsky will change description.
In the future I am going to supply the RX by a 2s lipo directly (and servos by regulator).
Regards Alois
Ps. my personnel opinion is, that the loss in voltage happens RX-internally.
It doesn't seem to be a problem of the BEC.
But on the other hand if the input voltage is high enough that doesn't matter.
New Info (8 August) : I've got the Archer R8 pro yesterday.
It is really better. Shows RX-Voltage in telemetry like RX6R or Jeti duplex R8.
On the ground with Servo movements Voltage drops from 5.1 to 4.9 V what is pretty normal.
Worked even with a very old/scrap 4-cell NiMh.
Haven't tested airborne yet. (don't get the dammed engine running)
(8 September) I've made some flights now. everything worked well.
