How to solve servo jitter with Archer GR6?

[hotdogx]

I have a new X-Lite TX and Archer GR6 RX. Have it all set up in a DLG that uses two Dymond D47 servos in the fuse and two Hitec HS-45 servos in the wings. During setup the GR6 RX was outside the fuselage, running off a 4.8V 250 mah NiMH battery, and no servo jitter. I installed a 4.8V 350 mah NiMH and the GR6 RX into the fuselage (battery in nose, RX behind battery, and two Dymond D47s behind RX) and I now have significant servo jitter on the two Dymond D47s. I can eleminate it by grabbing one of the antennas, so that tells me the telemetry transmission is getting into the two Dymond D47 servos. Moving the antennas as far forward as possible does not cure the issue. My conclusion is I need to replace the Dymond D47 servos with a different brand, perhaps some with metal cases like the KST servos.

Does anyone have recommendations on servos that are not affected by the GR6 telemetry RF?

 

[Slopeflicker]

Is the fuse carbon? Is your tx too close to the rx? Are your antenna whiskers seperated?
just my first thoughts

 

[Konrad]

No grabbing the antennas does NOT tell you the telemetry transmissions are the source of your jitters.

A large source of jitters are florescent light. Are there any in your work shop. Nice neat servo lead runs can result in the servo leads picking of signals (act like antennas). As the D-47 uses flat ribbon servo leads try twisting (braiding) the 3 lead wires. Also try testing with the 250 mAh battery.

 

[hotdogx]

fuse is glass - no carbon at all
moving TX well away from RX makes no difference
antenna whiskers separated as far as they can be (6-7") makes no difference
florescent light on or off makes no difference
twisted/braided leads makes no difference
using original 250 battery makes no difference
Pretty sure it's telemetry RF getting into the servos, hence my question what servos are not susceptible to RF?

 

[Konrad]

Is this the digital buzz or actual jitter, movement. Are your linkages free? Do the servos jitter with the connecting rods disconnected ( No load on the servo)?

Have you bound with telemetry off?

Most servo don't have an issue with RF (2.4 gHz) noise.

Can we see a photo of the installation? We may pick up on something just by seeing the install.

 

[hotdogx]

I am familiar with digital buzz, having used digital servos for many years. It is actual jitter - you can see the servo arms moving. Haven't bound it with telemetry off, but I want the telemetry. I've done an internet search and apparently this servo jitter is quite common with FrSky receivers that have telemetry, but not all servos are affected. I'd like to find out which servos are not affected so I can use those.

I don't have this issue with the GXR6 receiver and Dymond D47 servos in some of my other gliders, and the receiver antennas are very close to the servos in those gliders. Trying this GR6 receiver is the first time I've run into this problem. The easiest and cheapest solution might be to just go back to a GXr6 RX running ACCST.

 

[Konrad]

The only servo I'm aware of where some of the Older digital JR servos where some of the analog input filter where left off (removed to save cost) thinking the digital filtering were enough. Turn off the telemetry as a test. I've had great luck with KST X0-8 and XO-6.

 

[Flying Dutchman]

@hotdogx: do you know how to quickly turn off telemetry on the Rx? With the Archer Rx's it is simple, no need to bind a certain way.
In model setup (p2) scroll down to the receiver and click on the name (GR6). This will bring up a menu from which you select 'Options' - here you can turn off telemetry.

If you want to experiment with isolation, instead of grabbing the antenna's, you might try wrapping the servo's and leads in foil.

FWIW, I have a few GR8's and use std plastic case Corona and Hitec servo's with no jitter problems. However, they are probably not as close to the Rx as what you describe.

 

[ululi1970]

I believe archer servos have the option to reduce the power of telemetry to 25 mw. Just go to the radio page, select the receiver and choose the options menu. There you can select to reduce the power of telemetry. See if that works

 

[Wayne]

Not aware of this issue with your particular servos, but I may have missed any reports of this..

Quick test would be to bind with the telemetry off and see if it cures the issue. It certainly sounds like it may be an issue.

I have used many KST servos with no issues. In fact not sure any of the servos we offer have any issues with telemetry receivers.

 

[hotdogx]

I replaced the Dymond D47 servos with KST X06 servos and that solved the jitter problem. I have not had this servo jitter issue with my G-RX6 receivers running ACCST using Dymond D47 servos in two other gliders.

 

[Wayne]

It is interesting.. I'm really not aware of any jitter issues with the D47 servos. Are these brand new servos? I do know with some changes going on in China policies with Taiwan and some other things Dymond was looking for a new manufacturer for the D47. (I was trying to buy a bunch of them for the last years or so.) It is possible that they have a new manufacturer making them using a different control board.

 

[hotdogx]

Wayne,

These were 2008 vintage Dymond D47 servos. I have some 2019 Dymond D47 servos that are working fine with the G-RX6 RX in another DLG and a 2M glider. I read that the GR6 RX has a more powerful telemetry transmitter than the G-RX6 RX, so I'm guessing the extra power is enough to cause RF issues with the D47s. Thankfully the KST X06 servos are unaffected by the GR6 RX so I'm happy.

 

[Wayne]

I don't know.. Seems like the servos that have issues with telemetry receiver always have issues regardless of make or model of receiver. Best guess is those servos may have different logic boards in them.

 

[Flying Dutchman]

Wayne,

These were 2008 vintage Dymond D47 servos. I have some 2019 Dymond D47 servos that are working fine with the G-RX6 RX in another DLG and a 2M glider. I read that the GR6 RX has a more powerful telemetry transmitter than the G-RX6 RX, so I'm guessing the extra power is enough to cause RF issues with the D47s. Thankfully the KST X06 servos are unaffected by the GR6 RX so I'm happy.

Did you try adjusting the telemetry power, as suggested by @ululi1970? Seems like that would address the question of G-RX6 vs GR6 power.

 

[hotdogx]

No I didn't try reducing the telemetry power. Might try that with a bench test when I get another GR6 RX later.

 

[Landru]

I've encountered jitter with D-47 and a G-RX6 on ACCESS.

In my case, it occurred in a 1m DLG. The very tight fuselage pod pretty much forced me to place the receiver and both antennas close to the servos.

I solved the problem by using 25mW telemetry power. The lower power isn't an issue which such a small model, which can't be flown too far.

 

[hotdogx]

Good to know, thanks.