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Mar 17, 2017, 03:39 PM
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Spektrum issues?


Hi everyone, new here and as you can see by my name I have and still fly FM. I'm intrigued about 2.4 though and have looked into Spektrum, but there seems to be a lot of fake receivers out there and I've read quite a bit about "brownouts" causing planes to crash. I'm not seeing so much bad press on Futaba though and have flown Futaba FM for years. Opinions?
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Mar 17, 2017, 03:57 PM
Registered User
richard hanson's Avatar
You may note that theSpectrrm radios easily dominate the market
Fakery always follows the most popular equipment
As for brownouts, this just means there was not enough power, to the Rx and servos
All brands see this possibility.
Mar 17, 2017, 04:17 PM
S.A.D. member
ivanc's Avatar
All equipment experiences brownouts if the power source is improperly designed or set up. Most receivers recover instantly from brownouts which often is shadowed and not properly assessed.

Very early Spektrum receivers were slow to reboot. When a brownout occurs the receiver reboots so on those very early Spektrum receivers brownouts were especially pronounced sometimes leading to a crash. Spektrum addressed the issue and offered free update for all receivers which took a while to boot up. All updated receivers and all new receivers after those initial batches have an instantaneous start up - either on power up or after a brownout.

Having said that, even the very early Spektrum receivers which took ice ages (in microprocessor terms) to reboot, did not have an issue with properly sized receiver power supply (ESC with a quality BEC sized properly) or receiver battery pack.

The term "brownout" is wrongfully understood by 95% of the population and many claim to have experiences a "brownout" when they had signal loss without the receiver rebooting (during a brownout the receiver always reboots). The reasons for a signal loss are numerous but the most often one is poor receiver antenna location and orientation.

Ivan
Mar 17, 2017, 05:02 PM
Registered User
You see fewer reports of problems with Futaba because far fewer people are using Futaba.

I flew Futaba FM for years but they took so long getting into 2.4GHz and made some really bad equipment in the early days that I went over to Spektrum and have no intention of going back.

There are certainly some fake Spektrum RXs about but not many these days. However there are some very good low cost compatibles like the Lemon range. That's an advantage not a problem.

Steve
Mar 17, 2017, 05:45 PM
Get RAD! and stay RAD!
There are plenty of Spektrum haters out there too and forums are the easiest place for people to complain about a product or that it caused their model to crash when in reality, most issues are user error.

If you start reading the threads then you just need to filter and decide for yourself what's true and what is just someone else on the Spektrum hating bandwagon.

It's 2017, you won't find a bad radio set out there, the biggest difference will be a menu based radio vs open source one like the Taranis. Although learning a Taranis comes pretty quick so don't be afraid of the open source radios.

I fly both Frsky and Spektrum, both have been rock solid for me with correctly powered rx''s and antenna placement.
Mar 17, 2017, 06:27 PM
Registered User
Don't buy "Spektrum" receivers from ebay. They are probably 100% fake. That's the most important rule. Get them from a reputable shop.
Mar 17, 2017, 09:35 PM
Bo Edström, Sweden
2.4 GHz radios has matured so much today that one do not have to worry really about that part of a radio today if You buy a brand new radio today - regardless of brand I would say.
It is of course some quality differences between brands and between radios in one brand but the major brands have such good quality today that one have not to worry much about that part in my opinion. Spektrum, Futaba, Jeti, Multiplex, Grapner/SJ, Frsky, JR for example - pick any of their 2.4 GHz radio and it will work in most cases just fine.
Remember people come to forums when they have a question/problem so when You search for any brand on forums You will find questions/problems with any radio.
Some problems are grave and are easily found in forums and it is great they are exposed.
If You plan to buy a new 2.4 GHz radio today - Spektrum or Futaba - I would personally not worry about any radio made by them. If they do not have good enough radios to sell, well they will not get any sold. Naturally in a high end radio it will be some better components like better sticks and other higher qualty components then a budget transmitter.
I use Futaba myself because I think they have very good quality in general and rock solid 2.4 GHz protocol (I can only speak for Futaba FASST protocol). I have used my Futaba 14MZ for 10 years this year (I fly both in winter and summer, and I compete also in F3A). I have a Spektrum DX6i radio also for some indoor flying (it is OK but nothing I would fly any of my F3A planes with).

/Bo
Mar 18, 2017, 06:31 AM
Registered User
Buschbarber's Avatar
I first started flying RC in 1978. I used Futaba radios exclusively from then until 2007 when I sold my 9CAP and bought a JR XP9303 (a much better radio than the 9CAP). I bought the Spektrum DM9 module and finally was done with 72Mhz. I have two of these radios today and have never had any major issues. I just bought a Spektrum DX20. Spektrum is a solid product with very intuitive programming. Futaba was behind the curve in developing 2.4Ghz products which is another reason I switched back then.

As was mentioned, a Brownout can occur when the voltage to a receiver drops below the critical threshold. This is different with each manufacturer's radio but it is around 3.5v. It is usually the result of a voltage spike caused by high servo drain on the RX battery. Early Spektrum receivers had a slow reboot time so a Brownout could be mistaken for a Failsafe Event ( where the TX signal is blocked from the RX but the RX still has power). This is also called a Hold. All brands of radios can experience this Brownout. Spektrum redesigned the firmware in their Rx's so the reboot time was less than a second. RC radio owners have been educated to recognize when their RX power is inadequate. Using 6v RX batteries rather than 4.8v or using external BEC's that can handle 10a or 20a instead of 5a or less. Most Spektrum receivers have blinking lights that indicate a Brownout or a Hold. Spektrum has tools such as the Flight Logger or Telemetry that keeps track of antenna Fades, Frame Losses, and Holds to help with proper receiver placement in the aircraft.
Mar 18, 2017, 07:46 AM
Get RAD! and stay RAD!
Quote:
RC radio owners have been educated to recognize when their RX power is inadequate
Well, you would think, the amount of posts on here with people still claiming a brownout as a RF issue, especially if they are using Spektrum because they are just following the bashing crowd, is still quite high. Hence why a high % of radio issues are most likely user error no matter what the brand.
Last edited by i_am_mark_evans; Mar 18, 2017 at 07:55 AM.
Mar 18, 2017, 06:22 PM
Registered User
I disagree with the statement that "all" radios can experience a brownout. I have not tested all radios but I have bench tested my Futaba sfhss and tfhss receivers with nimh rc packs fully dischaged. The rxs reboot instantly (like my old am/fm systems did). Obviously, I will never fly on that condition. However, it is a peace of mind to know that if something happens, my receivers will not reboot with windows 95-like times and most likely kiss my planes good bye.
Mar 18, 2017, 08:51 PM
Registered User
Quote:
Originally Posted by Falcon_56 View Post
I disagree with the statement that "all" radios can experience a brownout. I have not tested all radios but I have bench tested my Futaba sfhss and tfhss receivers with nimh rc packs fully dischaged. The rxs reboot instantly (like my old am/fm systems did). Obviously, I will never fly on that condition. However, it is a peace of mind to know that if something happens, my receivers will not reboot with windows 95-like times and most likely kiss my planes good bye.
You would be incorrect in your disagreement. Brownouts can and will occur with any system that depends on a single battery pack as a power source.

A brownout will occur if the voltage sags too far to keep the receiver functioning. Modern receivers will reconnect quickly if the voltage recovers, but in an aircraft you also need to factor the load on the pack from the servo's, which on a discharged pack can readily pull the voltage down below functional levels and not let it recover.

The vast majority of actual brownout issues were a result of 2 things. The first is the move to LSD NiMH packs (which cannot deliver as much current as non-LSD packs) and the second is the newer 2.4GHz receivers which have a hard limit on how low a voltage they can operate on, particularly earlier designs which did not operate below 4V. Both became common at about the same time (2006-2008)That led to the case where driving 4-6 servo's hard could readily result in voltage sag below the minimum operating voltage of the receiver, causing a reboot after the voltage recovers.

Now brief spikes of this is far more common, and fast-rebooting receivers will handle this better, but it is quite possible for high control surface loads on an aircraft with a marginal power supply or discharged pack to drag the voltage below minimums for longer periods, which will still result in a brownout that no receiver can recover from quickly enough, because the receiver will not reconnect until it has sufficient voltage to operate.
Mar 19, 2017, 01:13 PM
Registered User
Not seeing a lot or reason to switch from FM, no rebooting required. One reason I've stuck with FM is that hardly anyone uses it, I even have a '91 approved AM on one plane that I fly once in awhile. Have never had interference issues like we had in the past when everyone flew those.
Mar 19, 2017, 02:10 PM
S.A.D. member
ivanc's Avatar
Quote:
Originally Posted by fmflyer View Post
Not seeing a lot or reason to switch from FM, no rebooting required.

. . .
That's the thing with FM - even though the receiver may be "rebooting" you may not even notice it. All you can notice is a slight sluggishness in the split second the receiver is recovering from the brownout.

Ivan
Mar 19, 2017, 02:34 PM
Balsa addiction since age 3
ScottSails's Avatar
Quote:
Originally Posted by fmflyer View Post
Not seeing a lot or reason to switch from FM, no rebooting required. One reason I've stuck with FM is that hardly anyone uses it, I even have a '91 approved AM on one plane that I fly once in awhile. Have never had interference issues like we had in the past when everyone flew those.
There is no technical reason to change.... I did because I was afraid of being shot down with other flyers forgetting to get the "pin" (or to be fair, me doing it to them).... I don't worry about that.
Of course the other reason is that most new radios can run circles around what I used to use in terms of models and programming. I used to have basically one transmitter per plane even though I did have futaba and hitec that did 6 or so models. I really like having only one now.
Scott
Mar 19, 2017, 06:22 PM
Proud to eat Kraut ;-)
Julez's Avatar
The issue with Spektrum and it's brownouts was the following:

1) Spektrum RXes rebooted when the voltage sagged below 3.2V, whereas RXes from Futaba still operated at 2.8V, which made Spektrum RXes more prone to brownout problems.

2) Spektrum RXes synchronized the Servo outputs, meaning all Servos start moving at the same time. This load spike caused a more pronounced voltage sag compared to Futaba RXes which sequenced the servo signals and thus spread the load over a longer time, thus reducing the severety of the voltage sag.

3) Spektrum RXes, being DSSS at that time, needed to scan the band after rebooting until they found the first of two channels the TX used. This could take a considerable time, in which there was no control possible, often leading to a crash. Futaba, in contrast applied FHSS and was able to reconnect in a split-second after rebooting.

Spektrum have since learned from their mistakes. They have switched to FHSS as well, thus providing not only better RF performance but also shorter reboot times. The early DSSS RXes ware also updated to adress that issue.

Nowadays, most systems work pretty flawless concerning their RF performance. Other features like TX and telemetry options count. Futaba is severely lacking in the telemetry department, do not buy. Spektrum is a bit better, but you should also check out FrSky, which offers most bang for the buck IMHO.


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