2 DMSX Sats...or one?

[Jason Courville]

Originally Posted by HEXAHYDRATE

Just follow the cautions I mentioned and you won't have problems.

Most of the Spektrum haters who have had failures can be attributed to user error. Like running HV servos with 1 single power lead and getting a voltage drop bad enough to go below minimum voltage the sats require to operate.

I have 100's of hours flight time with no failures.

Just for clarification, can you explain more about what you said about the single power lead and hv servos.
Thanks

[HEXAHYDRATE]

Some people have been known to power the FBL controller with only 1 servo wire from the power source. Running 4 HV servos off of one small wire can cause issues.

The servos could draw so many amps in some situations that just using a single power lead will not be enough, and the voltage drop could be bad enough to go below minimum voltage for the sats or other electronics to function. Which can obviously end poorly.

It is highly recommended on a bigger heli setup to run 2 or even 3 power leads into you FBL controller, plugging them into any unused ports in the unit. At least 2 for sure which will obviously double the amps you are able to draw.

This is just one of many examples of a situation where people have blamed the sats or Spektrum. When in fact it's user error/bad setup.

[jmtyndall]

Always 1 on anything smaller than 500mm for me

[DoubleCH]

[quote=HEXAHYDRATE;7015932]Just follow the cautions I mentioned and you won't have problems.[quote]
Agree good advice.

Like running HV servos with 1 single power lead and getting a voltage drop bad enough to go below minimum voltage the sats require to operate.

Not necessarily HV servos but in general high power ones especially aggressive tail servos. WIth ONLY my Savox 1290MG full size tail servo, when I wiggle the rudder stick fast enough on the bench motor not running it would brownout the FBL with stock YGE60A internal BEC. I'm now running external Castle BEC adjusted to 6.1V and no more brownout even with 3 high power aggressive cyclic servos. I don't know about Brain log, but with vBar log any brownout due to too much power draw from the servos is easy to see.. "3.3V rail low voltage" event log. You can also read the minimum BEC voltage recorded the current session. In my case, it was not voltage drop. It was the bad Sat leads. Like I said, I was expecting one finicky Sat harness would lead to system switching to the other Sat. Apparently the system still tried to use the data from the Sat with finicky leads. That's why I said that even though you have a good redundant system don't expect to slack off at any one point and expect the redundant system to cover it.

[HEXAHYDRATE]

I agree it does not have to be HV servos to cause problems. Just an example as I said. There are many other examples such as some of the V Bars having such a low capacity power bus it could cause the same voltage drop issue. I run multiple power leads on everything anyways. It's a couple dollars and a few minutes so why not even if you think you should be ok.

[Jason Courville]

Thanks for the clarification. I have a hobbywing 100a v3 and it comes standard with two BEC power leads. Someone had suggested to plug both into the flybarless on my Trex 500, now I know why. I wish all escs 50 amps and above had this.

[HEXAHYDRATE]

Yep that's exactly why there is 2 wires on there. Some of us run seperate direct 2S power to HV servos. We end up usually having to make our own Y harness or whatever to get more than 1 power lead. There are several creative ways to do it.

[DoubleCH]

Servo plugs are good for up to 10A. That's why BECs close to and beyond that run 2 leads.

[mattbeau]

I'm always leary of using sats only. I had a neuron brown out and a spirit have disconnect with satellite only setups. My oxy suffered with a few crashes till I changed I did however have no problems running two satellites on my mini photos running ikon, maybe it was the sockets on those other FBLs

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