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Futaba 7C FASST or JR DX7 Spektrum

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Old 09-25-2008, 07:24 AM
  #1  
jmorgan2942
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Default Futaba 7C FASST or JR DX7 Spektrum

I was wondering what everybodies opinion is on these two radio systems. I need to make a decision on which one to buy.
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Old 09-25-2008, 08:36 AM
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Default RE: Futaba 7C or JR DX7

Both are almost identical in how much programing they can perform. Both are small radios that will feel good in your hands. Problem is your hands will come to like holding them. Then when or if you move up to a higher end radio the larger size will feel bulky and will take a while to feel right. Only advantage I see one having over the other is Tower sells Futaba and you can catch good sales prices there.
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Old 09-25-2008, 09:33 AM
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Default RE: Futaba 7C or JR DX7

I am a happy Futaba 7CAF owner and was strongly considering adding a 7C FASST to my equipment. I couldn't get past the $100 price floor for Futaba full-range receivers. The Spektrum DX7 is a solid product, but it seemed to me like it was set up more for electric than glow. I fly mostly glow and I didn't like the fact that the DX7 didn't have a throttle kill feature built into it. You have to program a mix and assign it to a switch for each individual model.

I ended up going with Airtronics for 2.4Ghz FHSS. The RDS8000 has a terrific feature set and really good ergonomics. It's a bargain at $229 and the current "2nd Receiver Free" promo sweetens the deal even more. What locked it for me was Airtronics offering additional 92824 full range 8 channel 2.4Ghz receivers for $79.99 each. That makes additional spread spectrum receivers no more expensive than a premium 72Mhz FM/PPM receiver and crystal.

I still love my Futaba 7CAF and I expect to be flying it for a good long time to come. That having been said, Futaba should have been smart enough to not give me any reason to try Airtronics products in the first place.
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Old 09-25-2008, 09:53 AM
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Default RE: Futaba 7C or JR DX7

jmorgan,

Do a "dx7 and vs" search and you will find a bevy of opinions.

peace
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Old 09-25-2008, 11:38 AM
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Default RE: Futaba 7C or JR DX7

The only advantage I have found on the dx7 over the 7c is that I can purchase a receiver for around $50-$60 and all the Futaba start at $100.
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Old 09-25-2008, 05:58 PM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

Many of futaba racing die hards were using $160 149dp PCM receivers, $99 seems cheap now and you don't have to worry about the satelite receiver...
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Old 09-27-2008, 09:39 AM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

DX7 does have a throttle cut feature plus Model Match which has paid for itself 10 times over.
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Old 09-27-2008, 11:26 AM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

I have both and i must say i prefer the Fasst system
i had one brown out with the spectrum and now fly it
with a regulator and the capacitor (probably overkill)
but it makes me feel better,as for the fasst i have it in
a ducted fan intruder with one aerial laid on top of the ESC
with no problems what so ever, its now going into a Scorpion jet

Never did like the idea of multi receivers

have you seen the new weatronic 2.4 system http://www.weatronic.com/cms/index.php?lang=en

brian
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Old 09-27-2008, 12:17 PM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

" The Spektrum DX7 is a solid product, but it seemed to me like it was set up more for electric than glow. "

[>:] What a bunch of horsehocky !

Go with the unit that has Model Match.

... zak
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Old 09-29-2008, 04:42 PM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum


ORIGINAL: starzak

" The Spektrum DX7 is a solid product, but it seemed to me like it was set up more for electric than glow. "

[>:] What a bunch of horsehocky !

Go with the unit that has Model Match.

... zak
Sorry Big Ed, but Zak says you aren't allowed to have or express an opinion unless it matches his. That sounds fair doesn't it? [sm=thumbs_down.gif]
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Old 09-29-2008, 08:26 PM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

That's a helpful post, Bruce.

The DX7 was surely designed for glow more than electric, if only due to the bundling involved. How many DS821s have been dumped onto the market by electric flyers purchasing DX7s? Its design and programming were from the 7202, which nobody would say was designed for electrics more than glow.

Now, it'd be much more accurate to say that the DX6 was designed with electrics in mind, given that it was bundled with a park flyer receiver.
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Old 09-30-2008, 01:31 PM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

The dx7 is available as a "micro lite" system with 285 micro servos.

It's a very flexable radio system. The 7C and the DX7 are very comparable radios.
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Old 10-27-2008, 12:29 PM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

I have both a Futaba Fasst system and a Spektrum DX7. The Fasst system, which I have had the longest, has performed flawlessly and exactly as expected. The DX7 has shown the 'drop out' glitch often referred to in the forums. Read all the forums very carefully and compare the number of 'loss of control' posts.

The reasons that I purchased the DX7 were the availability of low cost receivers, model identifier and a 20 model memory but now I do not trust it and this screws up the fun of flying. I am going to relegate the DX7 to flying foamies and park flyers where I do not have the money or sweat equity at risk.

I also find the two receiver approach to be a pain during installation and I now suspect that this is a band aid to fix a fundamental design weakness.

My research has led me to believe that the Spektrum design is not as fundamentally robust as the Futaba. They are not equivalent and use entirely different approaches to spread spectrum technology.

Many on these forums will vehemently defend the Spektrum approach but this is to be expected as nobody, including me, likes to face having made a poor decision. The data was available on the forums and I did not do enough research.

Of our club of 73, at least 3 of us have had drop out problems with the DX7 and this is at least 30% of those using the system.

Batteries are definitely an issue. Spektrum says use a 5 cell battery but do not supply this pack with the system and it should not be required. The reason that batteries are such an issue is that the Spektrum approach to implementing spread spectrum is extremely vulnerable to noise on the power/ground lines supplying the receiver. A noise spike on the power supply sends the receiver into a reboot mode which can take up to 13 seconds to complete. No amount of software fixes are going to get around this as it is inherent in the approach they use to implementing the system. Whenever motors are on the same power supply bus, as is always the case because we are driving servos, there will be noise spikes on the ground and power lines. I think that it is mostly the luck of the draw if you happen to get a noisy servo. Capacitor filtering will probably help as will a higher voltage supply pack and low internal battery impedance but these are not fixes rather they just lower the probability of experiencing the problem.

Hope this helps you make an informed decision.
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Old 10-28-2008, 08:55 PM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

THE FUTABA 7C AND 6EX 2.4 ARE GREAT SYSTEMS. I HAVE BOTH AND FLY GAS AND GLOW USING 1500 NICAD PACKS AND HEAVY DUTY SWITCH. WE HAVE TWO GUYS FLYING DX7 AND THEY HAVE HAD THEIR RECEIVERS TO UNBIND ON THEM BUT LUCKY IT WAS ON THE GROUND. THE ONLY THING ON THE NEW RADIOES 2.4 IS YOU WILL FIND THAT SOME SERVOES WILL NOT WORK ON THEM. THIS IS AS I HAVE FOUND OUT FLUSTRATING BUT OHHH WELL. TRO Y BUILT PLANES CAN HELP LETTING YOU KNOW WHICH SERVOES WILL WORK BUT THEY DONT KNOW ALL OF THEM. SO FOR I KNOW THAT HI TEC 645 AND FUTABA 3001,3004,3010,3152,9152,3151 ALL WORK ON THE 7C AND 6EX AND THE RADIOES ARE GOOD.
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Old 10-28-2008, 09:32 PM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

Don't know of any servos that won't work on either Spektrum or Futaba other than one foamy type that uses 5 wires.
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Old 10-28-2008, 10:24 PM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

WELL MAYBE YOU CAN HELP ME OUT. THE POWER HD-9150 SERVO DOES NOT WORK RIGHT ON MY FC 2.4 SYSTEM. THE THING TURNS 90 DEGREES CLOCKWISE WHEN I TURN ON THE RECEIVER AND THEN COUNTER CLOCKWISE BACK TO CENTER AFTER THE RECEIVER BINDS TO TRNSMITTER. IF YOU ARE USING FUTABA 2.4 7C OR 6EX AND HAVE TRIED THESE SERVOES AND THEY WORK FOR YOU LET ME KNOW. THIS SERVO WORKS FINE ON MY OLD 72 SYSTEM BUT NOT ON 2.4. ALSO BILL AT TBM TELLS ME THERE ARE SOME HI-TEC SERVO THAT WILL NOT WORK ON FUTABA FASST SYSTEM DO'NT REMEMBER WHICH ONES.
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Old 10-29-2008, 06:04 AM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

Sorry, should have left out Futaba as I only have Spektrum. Had a Futaba 9C that worked very well before Spektrum came out.
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Old 10-29-2008, 06:05 AM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum


ORIGINAL: idedave

I have both a Futaba Fasst system and a Spektrum DX7. The Fasst system, which I have had the longest, has performed flawlessly and exactly as expected. The DX7 has shown the 'drop out' glitch often referred to in the forums. Read all the forums very carefully and compare the number of 'loss of control' posts.

The reasons that I purchased the DX7 were the availability of low cost receivers, model identifier and a 20 model memory but now I do not trust it and this screws up the fun of flying. I am going to relegate the DX7 to flying foamies and park flyers where I do not have the money or sweat equity at risk.

I also find the two receiver approach to be a pain during installation and I now suspect that this is a band aid to fix a fundamental design weakness.

My research has led me to believe that the Spektrum design is not as fundamentally robust as the Futaba. They are not equivalent and use entirely different approaches to spread spectrum technology.

Many on these forums will vehemently defend the Spektrum approach but this is to be expected as nobody, including me, likes to face having made a poor decision. The data was available on the forums and I did not do enough research.

Of our club of 73, at least 3 of us have had drop out problems with the DX7 and this is at least 30% of those using the system.

Batteries are definitely an issue. Spektrum says use a 5 cell battery but do not supply this pack with the system and it should not be required. The reason that batteries are such an issue is that the Spektrum approach to implementing spread spectrum is extremely vulnerable to noise on the power/ground lines supplying the receiver. A noise spike on the power supply sends the receiver into a reboot mode which can take up to 13 seconds to complete. No amount of software fixes are going to get around this as it is inherent in the approach they use to implementing the system. Whenever motors are on the same power supply bus, as is always the case because we are driving servos, there will be noise spikes on the ground and power lines. I think that it is mostly the luck of the draw if you happen to get a noisy servo. Capacitor filtering will probably help as will a higher voltage supply pack and low internal battery impedance but these are not fixes rather they just lower the probability of experiencing the problem.

Hope this helps you make an informed decision.
There is a lot of incorrect or dated information in this post that I would not use to help make up my mind. The reboot issue was fixed quite some time ago and if you happen to have an older receiver then Spektrum will upgrade it for free. It was caused by the receiver battery voltage dropping below a certain value. The battery information in the post is very misleading in that the new 2.4 ghz receivers of all manufacturers have a low voltage threshold that did not cause a problem with the 72 mhz systems and using a 5 cell battery is simply a good, cheap solution to help prevent the problem - remember all manufacturers systems have this same issue for the 2.4 ghz systems. Next time you are at the field see how many experienced 2.4 flyers are still using 4 cell batteries except for parkfliers.

Do yourself a favor and also look at the Airtronics 2.4 ghz system. They are an excellent company that many of us have dealt with for years. You get two receivers and a transmitter for $229.

I do not own a Futaba, Spektrum or Airtronics 2.4 system so I don't think I am being biased. You have some great choices so take your time and get the big picture.

Howard
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Old 10-29-2008, 08:39 AM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum


ORIGINAL: Howard


ORIGINAL: idedave

I have both a Futaba Fasst system and a Spektrum DX7. The Fasst system, which I have had the longest, has performed flawlessly and exactly as expected. The DX7 has shown the 'drop out' glitch often referred to in the forums. Read all the forums very carefully and compare the number of 'loss of control' posts.

The reasons that I purchased the DX7 were the availability of low cost receivers, model identifier and a 20 model memory but now I do not trust it and this screws up the fun of flying. I am going to relegate the DX7 to flying foamies and park flyers where I do not have the money or sweat equity at risk.

I also find the two receiver approach to be a pain during installation and I now suspect that this is a band aid to fix a fundamental design weakness.

My research has led me to believe that the Spektrum design is not as fundamentally robust as the Futaba. They are not equivalent and use entirely different approaches to spread spectrum technology.

Many on these forums will vehemently defend the Spektrum approach but this is to be expected as nobody, including me, likes to face having made a poor decision. The data was available on the forums and I did not do enough research.

Of our club of 73, at least 3 of us have had drop out problems with the DX7 and this is at least 30% of those using the system.

Batteries are definitely an issue. Spektrum says use a 5 cell battery but do not supply this pack with the system and it should not be required. The reason that batteries are such an issue is that the Spektrum approach to implementing spread spectrum is extremely vulnerable to noise on the power/ground lines supplying the receiver. A noise spike on the power supply sends the receiver into a reboot mode which can take up to 13 seconds to complete. No amount of software fixes are going to get around this as it is inherent in the approach they use to implementing the system. Whenever motors are on the same power supply bus, as is always the case because we are driving servos, there will be noise spikes on the ground and power lines. I think that it is mostly the luck of the draw if you happen to get a noisy servo. Capacitor filtering will probably help as will a higher voltage supply pack and low internal battery impedance but these are not fixes rather they just lower the probability of experiencing the problem.

Hope this helps you make an informed decision.
There is a lot of incorrect or dated information in this post that I would not use to help make up my mind. The reboot issue was fixed quite some time ago and if you happen to have an older receiver then Spektrum will upgrade it for free. It was caused by the receiver battery voltage dropping below a certain value. The battery information in the post is very misleading in that the new 2.4 ghz receivers of all manufacturers have a low voltage threshold that did not cause a problem with the 72 mhz systems and using a 5 cell battery is simply a good, cheap solution to help prevent the problem - remember all manufacturers systems have this same issue for the 2.4 ghz systems. Next time you are at the field see how many experienced 2.4 flyers are still using 4 cell batteries except for parkfliers.

Do yourself a favor and also look at the Airtronics 2.4 ghz system. They are an excellent company that many of us have dealt with for years. You get two receivers and a transmitter for $229.

I do not own a Futaba, Spektrum or Airtronics 2.4 system so I don't think I am being biased. You have some great choices so take your time and get the big picture.

Howard
Certainly a wealth of misinformed information(?) when you ask about the two systems
if you look at the current setups available - the Spektrum (DSM2) has a huge sales advantage over the others
the reasons why are pretty straightforward.
Best selection of rx to match applications
This includes tx use with everything from largest aerobatic type rx, to tiny integrated rx/gyro one ounce helis which perform stunningly .
And one tx works with all.
The "battery issues' were resolved with the Spektrum-but the memory lingers on-
Features of various brand tx is a matter of taste
some like switches all over the place low med high throttle etc..
some prefer simple setups -a discrete adjustable trim.
What one flies , seems to heavily influence the choice



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Old 10-29-2008, 09:02 AM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

Hmmm, I actually wish that Howard was correct and that my conclusions are based on out of date information. Unfortunately for me, my DX 7 is almost brand new. Even on first ground turn on, I notice that it sometimes takes up to 10 seconds for the receiver to boot up. The Futaba invariably boots up in less than a second. The basic problem is that all of the 2.4 receivers are little computers that have to go through a power up boot sequence when they start up. This makes them vulnerable to power supply glitches. Just like your home computer, if there is a momentary power glitch they have to reboot. My direct experience is that the DX 7 has a very long boot time even when using a 'new' receiver. The power glitches that trigger a reboot do not have to be due to the fact that your battery pack is depleted. They can easily be due to a momentary high current surge or a noisy or binding servo and only need to last for milliseconds.

So it is very important with a spread spectrum implementation that the boot time of the receiver is very quick. This does not appear to be the case with the DX 7. I wish it were not the case but my direct experience is that the Spektrum implementation has a very long boot up time even using a very new system. I see it on the ground and I have seen it in the air where it almost caused me the loss of an expensive aircraft.

It is quite true that using a higher voltage pack especially one with low internal impedance will lower the statistical probability of triggering a reboot but the real design solution is a system that has a very short reboot sequence.

My advice is to take your time and read all the forums. When I went back to read the forums I found lots of references to this loss and then regaining of control issue. I wish that I had done more reading before I spent my money.
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Old 10-29-2008, 09:23 AM
  #21  
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

Bought the DX7 when they first came out and never had a reboot. The fact that it takes a while to connect has no bearing on anything. Once they lock together it's low batt., a 4.8 volt batt. is considered as good as dead at 4.8 volts. I use the one that came with the Spekrum in a 1/4 scale Corby Starlett and get three flights before it gets down to 5.2 volts, when it gets recharged. Bad switches, broken wiring, dumb thumbs, ESCs not up to the job, rcvr always gets the blame for. Look after those other things and the Spektrum will give little trouble.
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Old 10-29-2008, 09:56 AM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum


ORIGINAL: idedave

It is quite true that using a higher voltage pack especially one with low internal impedance will lower the statistical probability of triggering a reboot but the real design solution is a system that has a very short reboot sequence.

My advice is to take your time and read all the forums. When I went back to read the forums I found lots of references to this loss and then regaining of control issue. I wish that I had done more reading before I spent my money.

You know the problem with people like you posting this kind of nonsense is that some of the un-initiated who come to these forums seeking advice, might actually believe you...

While it may be fair to compare the startup process on the 2.4 systems to a computer booting up and I have done so myself, your conclusion is flawed.

The initial link time on a DSM system arises from the tx picking two frequencies and then the rx has to scan the frequency range looking for the two frequencies the tx is using. Once that happens, no matter how many times you cut the power to the rx whether by switching it off or a power brownout, the rx will come back online in less than 1/2 second using those same two frequencies. It will also display flashing lights on the rx to indicate a power brownout has occurred so you know it's happened and you have a problem if those lights are flashing on landing. This ability is due to the "Quick Connect" firmware update which has been available for some time now, and as has been mentioned if you have an older rx, Horizon will upgrade it for free. This "reboot" time of less than 1/2 second is very similar to what one might see if a 72MHz system suffered the same low voltage type situation. After looking at a lot of different modeler's power systems I see, I'm convinced that a lot of the "I got hit!" shouts coming from the flight line in the past were due to power brownouts and the resulting momentary loss of control on the 72MHz systems.

If you shut off the tx and then turn it back on, then yes it will take somewhere in the 2 to 5 second range for the rx to pickup the two new frequencies. You aren't in the habit of turning off your tx while flying are you????

Your evident "expertise" does not seem to support your assertion that the multiple rx layout is inferior. It's all about signal path diversity and the radio guys can speak to that, but from my perspective considering the short wavelength of the 2.4GHz band, having multiple signal paths available is desirable. About the only thing you've got right is that the two systems are different implementations of the technology....

You also don't mention that on the 7 channel and above rx's, there is a Flight Log device available that will TELL you without any speculation from the un-informed, the quality of your RF link to the model and you won't see that on a FASST system.

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Old 10-29-2008, 10:08 AM
  #23  
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

A very interesting and informative post from Gord. He validates that the Spektrum system takes a long time to boot up on the ground. Unfortunately, this is exactly the problem. Also the '4.8v is as good as dead' comment is very revealing. NiCd batteries still have most of their energy at 4.8v. A system that has so little operational headroom that the difference between 5.2 v and 4.8 v is all that stands between you and a loss of control is pretty scary.

When I talked to Spektrum support, the first question they asked me was 'did I have a binding servo'. This was the trigger that lead me to the issue. This is a known problem but there is no easy fix because this particular implementation of spread spectrum has an inherently long start up time.

I completely understand that people want to assure themselves that their radio is 'rock solid' and I certainly don't want to make anyone upset. I am just reporting what I have seen and my conclusions. I hold a Master's degree in digital electronics engineering so I have some vague idea what I'm talking about. Of course, anyone can be wrong.
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Old 10-29-2008, 10:20 AM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

Radio systems are not religion. People should not get upset about informed dissent. I have never had a 'drop out' problem on 72 MHz but I have had a drop out on the DX 7, and no I did not shut off the transmitter. I really hope that you are guys are right about the DX7. I would like nothing better than to regain my confidence but when you have seen your expensive and dangerous model flying all by itself for an extended period of time, it causes you to question the gospels.
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Old 10-29-2008, 10:28 AM
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Default RE: Futaba 7C FASST or JR DX7 Spektrum

What bearing does it have as to how long it takes to connect. Once it's connected, it stays. Mine takes from 2 to 5 seconds to connect. I can wait. As far as the batt. is concerned, fully charged nicad is around 5.6 volts. If you were to look at on a graph it will hold that with a slow drop, down to 5 volts at the beginning of the drop off, so my 5.2 is the safety factor. What does a binding servo have to do with the start up time.? Afraid I'm just an eyeball engineer and used the stuff over the last 40 yrs. This is the next best thing since proportional radio
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