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Old Dec 28, 2012, 03:40 PM
Hitec/Multiplex USA
MikeMayberry's Avatar
Poway, California, United States
Joined Sep 2000
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Quote:
Originally Posted by Kambalunga View Post
Your SPS-port works only up to 8S and without galvanic seperation of RX battery ground and drive battery ground direct in your RX. Not really what I called a good design as measurement and control engineer. When the drive battery fail and this happen frequently as a RX-battery fail. Then fall you with your SPC-Port out of the sky. Your Optimas has the higher brownout voltage.
Having a drive battery go below 3.5v total (minimum operating voltage which is same as Spektrum RX's unless they have changed that) would only happen if the connection fails and then you're toast anyways!

Note the Minima RX's that do not have telemetry or the SPC have a 2.5v minimum voltage threshold.

Mike.
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Old Dec 28, 2012, 04:01 PM
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Deutschland, Hessen, LA
Joined Jan 2009
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Quote:
a. Reset voltage is 3.5v. The cause of many problems with 2.4 systems is when people use low power 4 cell packs with high torque servos and they brown out. Optima cut off voltage is 3.5v, so we suggest a 5 cell pack if NiMH or NiCD for the servos.

The old AR6200 works down to 3V.
A AR500 2.7V and a AR6255 2.5V.

Your Minmas use a linear voltage regulator vs the switchmode voltage regulator in your Optimas. The Optima bottle neck is the switchmode voltage regulator.

Quote:
SPC Is Not Recommended For Use In Anything But An Electric Power Model - Q&A 5.1 above also refers. "I've stated many times that I do not think the SPC should be used in anything but an electric model because in those you are relying on the BEC to supply power and not a carefully chosen battery. Not to mention the telemetry info from your mail flight battery in electric allows you to fly with confidence that you are not going to lose power unexpectedly. For non electric models where you select your battery, the telemetry will tell you how the pack is performing, even if you just wiggle the sticks for a few seconds (which I do before every flight BTW.) If you are using a battery that allows the voltage to sag to the point of brownout... YOU HAVE THE WRONG BATTERY!!! The SPC has telemetry priority so that's the voltage you will see and not the servo battery which I feel is the most important. The upcoming "Blue" Sensor Station will have the ability to read an additional battery and amperage so when this is available you will have the ability to monitor both batteries so that may be another option because at least you can monitor the servo battery. - Mike.
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Old Dec 28, 2012, 04:02 PM
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I also have the A9, to compare it with another TX you have to consider the convenience of the touch screen. You need to try one to help you decide, good luck with your purchase. PS, I fly E-powered scale models and find the SPC port with it's flight pack battery telemetry very reassuring.
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Old Dec 28, 2012, 05:05 PM
You can't take the sky from me
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United States, OH, Cincinnati
Joined Aug 2011
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The advantage of the optimas is that with the flight pack plugged into the spc, your RX pretty much can't brown out, unless your connection breaks. Even a 2s pack won't say below 3v or so. It may have a slightly higher brownout voltage, but if it does get that low on the spc, something else is seriously wrong.
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Old Dec 28, 2012, 05:25 PM
They Call him Dead!
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United States, SC, Pawleys Island
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Quote:
Originally Posted by AndyKunz View Post
I have noticed that, and tried to reply accordingly. Hopefully I was not "dogmatic" too much either

Andy
Not in the least! My comment was only meant to ensure that my intentions were not misunderstood.
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Old Dec 28, 2012, 09:05 PM
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United States, CA, Garden Grove
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Still cogitating about DX-8 vs A-9 , both have a lot of good features and seem to be of good quality and reliability. My DX-6 had trim and programming button problems early on but has been reliable for many years.

BTW: Make sure that pigtail connector to power the Optima receiver via SPC port is plugged in with correct polarity, I nearly fried my UBEC that powers the servos, but disconnected just in time.
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Old Dec 28, 2012, 11:44 PM
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Australia, SA, Adelaide
Joined Sep 2007
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The hitec has 1 more channel , touch screen and cheaper receivers . When I was looking for another tx I did my homework and went to the store to check out the spek.8 . I didnt even ask them to get it out of the glass display case . It looked so cheap I was outa there so quick . Got the a9 and havent looked back . Just in case Im accused of being biased which I am I also have a JR 10x with a spek. modual which stays in the cupboard most of the time . Havent had a prob. with either 2.4 setup and futaba rx are just too expensive to go there . So do your home work and get which one feels and looks good to you , I think you will choose the hitec unless your insane , cheers from the pope
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Old Dec 29, 2012, 02:24 AM
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Deutschland, Hessen, LA
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Quote:
Originally Posted by copperbricks View Post
The advantage of the optimas is that with the flight pack plugged into the spc, your RX pretty much can't brown out, unless your connection breaks. Even a 2s pack won't say below 3v or so. It may have a slightly higher brownout voltage, but if it does get that low on the spc, something else is seriously wrong.

You need 2 batteries to be redundance-free with SPC.
With other systems has you with 2 batteries redundance.
Like the Spektrum Powersafe RX or the Spektrum compatible Futaba PSS2018 or the Powerbox RXs and all digital connected without the spaghetti syndrome. Spektrum has far more possbilties for giant scale and I mean really giant scale, like 25kg upwards to 150kg. The other thing with the DX8 has I an inbuild data logger. The DX8 log direct to the SD-Card.

Then all major producer use digital communication between host and RF-modul. Even Multiplex M-Link is full digital, has the lower latency and better resolution use FH-DSSS vs FHSS. But only Hitec use the Stone Age PPM protocol with erratic long latency.

Sure you can whitewash all this Hitec shortcomings, like the need for a SPC port, high brownout voltage, high latency, no high current capable RX avaible, PPM protocol, high latency, low resulution. Multiplex can this all much better as Hitec, but Hitec America suppressed M-Link in the USA.
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Old Dec 29, 2012, 09:38 AM
Yes, "that" Karl...
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Canada, BC, Burnaby
Joined Mar 2007
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FWIW, I own an A9 and was finally able to sell my DX6i that I had for flying the micro planes and helis that use DSM2/X. I use a module produced by Hammer22 so that I can transmit DSM2/X from my A9. It has made flying these little aircraft so much more enjoyable to be able to use a quality radio that feels proper in my hands. (The DX8 just doesn't fit my hands, but that's personal preference.)

A fellow flyer bought an A9 after playing with mine, then was looking at picking up a used 9503 to have a comfortable quality radio to fly his old Spektrum gear on. He saw my module perform and has now decided to stick with one radio. The fact that the A9 is module based was a huge selling feature for me when I shopping for a new radio. The ability to update the transmitting hardware is more valuable in my mind than being able to update the firmware.

Whatever happens, make the choice that makes you happy. Don't make the choice to make us happy. I'm just giving you more info to make that choice with.
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Old Dec 29, 2012, 10:33 AM
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United States, AK, Anchorage
Joined Oct 2011
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Quote:
Sure you can whitewash all this Hitec shortcomings, like the need for a SPC port, high brownout voltage, high latency, no high current capable RX avaible, PPM protocol, high latency, low resulution. Multiplex can this all much better as Hitec, but Hitec America suppressed M-Link in the USA.
I love the SPC port... could view main battery voltage without the need for a telemetry module. Brownout is a thing of the past for me. I never had a problem with latency even side by side with the faster futaba... And I fly 3D. Never heard of a RX not being able to handle any high drawing servo if powered adequately... Certainly I never have. Don't even know about the PPM protocol and don't care as long as the radio performs... and it does. There's latency listed twice. As far as resolution... I never had a problem getting a 3D throw I was shooting for.

I think it's funny how all you have is bashing Hitec... If you noticed, the Hitec guys on here tout their A9, not bash Spektrum.
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Last edited by bryansifsof44; Dec 29, 2012 at 10:42 AM.
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Old Dec 29, 2012, 11:12 AM
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Deutschland, Hessen, LA
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I see, Mike need the cavalry.
http://www.rcgroups.com/forums/showp...ostcount=23095
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Old Dec 29, 2012, 11:42 AM
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United States, AK, Anchorage
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I am by no means the cavalry... Just a Happy A9 user.
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Old Dec 29, 2012, 12:07 PM
You can't take the sky from me
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United States, OH, Cincinnati
Joined Aug 2011
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you don't need two batteries to be redundant on the spc... Just plug the drive battery into the spc, and then into a bec, either separate or in the esc, which then goes into the rx. Also, I think the high voltage concerns, andppmlatency are somewhat irrelevant, because he's talking about flying scale electrics, probably nothing above 35v. Also, Latency is really more relevant for the big giant scale stuff with high speed digital servos, with smaller stuff, there's a lot of stuff you can up[grade to improve responsiveness before going to the rx. Really, the A9 should be compared with a 9503, they have more parallel features-sliders, 9 ch etc.
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Old Dec 29, 2012, 12:22 PM
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Quote:
Originally Posted by Kambalunga View Post
Well - there seems to be two camps. One, Hitec users, are telling the OP about their experiences with THEIR radios. The other camp, spektrum, seem intent on only trying to tear the other guy down, and generally fling poop at the walls. I'm looking squarely at you, Kambalunga.

Hopefully you'll note the antics when making your decision, E-Challenged...
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Old Dec 29, 2012, 04:13 PM
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The major remaining concern with the A9 is lack of a "model match" feature. Don't ask!
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