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Spektrum 7 channel radio stuff

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Spektrum 7 channel radio stuff

Old 03-28-2010, 11:24 AM
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LargeScale88
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Default Spektrum 7 channel radio stuff

Hello again, for my next airplane, the great planes matt chapman eagle 580 53" span, I want a 2.4 ghz system. I am looking at the 7 channel with 4 ds821 servos, and an ar7000 reciever. It does not come with a reciever battery. What would be the best choice? 6v or 4.8? Ive heard bad things about the 4.8, and if I went with the 6v reciever battery, does this mean i have to purchase a regulator? Or what all do I have to purchase with the spektrum 7 channel 2.4 ghz radio??


Thanks
Old 03-28-2010, 11:49 AM
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jaka
 
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Default RE: Spektrum 7 channel radio stuff

Hi!
Nothing wrong with using 4,8V batteries for a Spektrum radio if you know what you are doing!!
I use "RED" GP NiMH cells in my pylon racers (4,8V , 850mAh). These are cells that can put out more amps than ordinary NIMH cells.
The new typ NiMH cells (i.e "Enelope" etc) can not put out as much power but will keep the the charge for longer periods of time so you will not loose as much power over time (but who cares when charging is no problem (I charge with my 30 year old , 50-100mAh
JR wall charger).

Some advise!
Don't use heavy standard servos in that small plane! Much better is to use Hs 225 typ servos and Hs 81 or 85 servos for throttle.
Light airplanes always fly better (and last longer)
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Old 03-28-2010, 12:25 PM
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dan4466
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Default RE: Spektrum 7 channel radio stuff

Dont use a 4.8V with the 2.4 Spektrum. Yes, some have used it and got away with it and many haven't. I talked to a Horizon Hobby tech and he said to always use a 6V with the Spektrum 2.4 No it doesn't say last I checked in the radio owners manual, but he adimtted, it should. I have the DX7 and its a great radio. The 821's would work great, but you would be adding a couple ounces of weight campared to the Hitec 225's. Personally, I'd use them if I had them.
Old 03-28-2010, 12:26 PM
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Default RE: Spektrum 7 channel radio stuff

Mine came with a 4.8v 1100mah pack. No problems. They will take 6v without a regulator. If in doubt about the quality of your 4.8v pack use a 6v pack.
Old 03-28-2010, 04:26 PM
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Default RE: Spektrum 7 channel radio stuff

So if I went with the 6v for battery, I have to get a regulator?????
Old 03-28-2010, 05:18 PM
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Default RE: Spektrum 7 channel radio stuff

No, you do not need a regulator. The 5 cell battery is no problem.
Old 03-28-2010, 05:25 PM
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Default RE: Spektrum 7 channel radio stuff

Hey Largescale,
I'm going to stick my nose into your business. I have noticed that you are posting a lot of questions on a lot of forums. In all honesty if you get 5 responces there will be 5 different opinions. Do you belong to a local club? If not I suggest that you seek one out. Sometimes by just observing what experienced modelers are using and doing can answer a lot of questions. Plus there is not a lot better than hands on modeling.

steve
www.hoosierdawnpatrol.com
Old 03-28-2010, 06:01 PM
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Default RE: Spektrum 7 channel radio stuff

I started using 5 cell, 6volt battery for my RX's 25 years ago. I never had a problem, and I am now using MiMh 6 volt with my jr 2.4 (same type of system) and I have several planes with them in it. No problem and I have been running this system for three years now.

You will not need a regulater to use the 6 volt battery with you RX.

sticks
Old 03-28-2010, 07:22 PM
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Default RE: Spektrum 7 channel radio stuff

Ok. Thanks.
Old 03-28-2010, 07:44 PM
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Default RE: Spektrum 7 channel radio stuff


ORIGINAL: dan4466

Dont use a 4.8V with the 2.4 Spektrum. Yes, some have used it and got away with it and many haven't. I talked to a Horizon Hobby tech and he said to always use a 6V with the Spektrum 2.4 No it doesn't say last I checked in the radio owners manual, but he adimtted, it should. I have the DX7 and its a great radio. The 821's would work great, but you would be adding a couple ounces of weight campared to the Hitec 225's. Personally, I'd use them if I had them.
Dan's quote suggests that using 4.8v Rx batteries is a death warrent for your plane. Not true. Many use the 4.8v 1100 mAh NiCd battery provided with the DX7 package with no problems. If you don't check the health of your battery as part of your preflight you may count yourself in with the victims. Mfg. reps realize that they are dealing with a broad range of customers. Some follow good battery maintenance practices and some don't. Using a 6.0v (5 cell) will give you added insurance but will not protect you from bad battery maintenance practices. Check your battery's state before every flight. 6.0v batteries can fall below the 4.something voltage that is the low water (voltage)mark that causes the problems.

Good luck with your DX7 and great flying!

Oh, and if you don't want those DS821's PMme and we can cut a deal.


Old 03-28-2010, 07:54 PM
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Default RE: Spektrum 7 channel radio stuff


ORIGINAL: SeamusG


ORIGINAL: dan4466

Dont use a 4.8V with the 2.4 Spektrum. Yes, some have used it and got away with it and many haven't. I talked to a Horizon Hobby tech and he said to always use a 6V with the Spektrum 2.4 No it doesn't say last I checked in the radio owners manual, but he adimtted, it should. I have the DX7 and its a great radio. The 821's would work great, but you would be adding a couple ounces of weight campared to the Hitec 225's. Personally, I'd use them if I had them.
Dan's quote suggests that using 4.8v Rx batteries is a death warrent for your plane. Not true. Many use the 4.8v 1100 mAh NiCd battery provided with the DX7 package with no problems. If you don't check the health of your battery as part of your preflight you may count yourself in with the victims. Mfg. reps realize that they are dealing with a broad range of customers. Some follow good battery maintenance practices and some don't. Using a 6.0v (5 cell) will give you added insurance but will not protect you from bad battery maintenance practices. Check your battery's state before every flight. 6.0v batteries can fall below the 4.something voltage that is the low water (voltage) mark that causes the problems.

Good luck with your DX7 and great flying!

Oh, and if you don't want those DS821's PM me and we can cut a deal. [img][/img]


ok, I have to come back. There is a problem with using the 6 volt battery's. We CAN NOT run them down to the 4.8 volts as with the 4cell packs.

When using the 6 volt battery's we must stop flying around 5.5 volts. Thats 1.1 volts per cell, get it. I know it took me some time to figure this out, but its true think about it. We never want to use our RX battery's down, below 1.1 volts per cell.

Old 03-28-2010, 08:16 PM
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Default RE: Spektrum 7 channel radio stuff

What point are you trying to make????
Old 03-29-2010, 02:07 PM
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Default RE: Spektrum 7 channel radio stuff

Hi!
Yeah! What's the point???
???????
Old 03-29-2010, 02:28 PM
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Default RE: Spektrum 7 channel radio stuff

The point is good pre-flight check includes testing your battery. You CAN kill a 6.0v battery pack below 5.5, or 5.0 or whatever if you abuse the pack.
Old 03-29-2010, 07:57 PM
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Default RE: Spektrum 7 channel radio stuff

I have read stories about 4.8 v battery packs crapping out in 2.4 ghz, and even airplanes crash. Whats the BEST battery for the 2.4 ghz system??
Old 03-30-2010, 04:40 AM
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Default RE: Spektrum 7 channel radio stuff

Ok, one last post. Some of the early 2.4 receivers had the voltage cutoff, ie, the voltage that it went into failsafe set realtively high. I beleive it was 3.2 volts, but don't hold me to that. In some situations where high torque digital servos were being used in larger planes, the drain on the battery was such that it would temporarily draw the 4.8 volt battery down below the cutoff voltage. This would cause the receiver to enter fail safe, every one called it a brown out! Since the voltage spike was a momentary event, the battery would bounce back, but the receiver, now in fail safe had to reboot and re-aquire the transmitters signal. The early 2.4 receivers took several seconds to do this, which as you might realize, was too long and the plane crashed.

Now, all receivers reboot in miliseconds, and the cutoff voltage for the problem receivers has been raised. The instant solution was to use a 5 cell battery, thus even when loaded would not dip below the cutoff voltage. The problem usually was in the larger planes. In electrics, when using a BEC and the higher voltage Lipos, you usually didn't see the problem.
Old 03-30-2010, 09:51 AM
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Default RE: Spektrum 7 channel radio stuff

OK - so it's about protecting your Rx from a low voltage spike. Use a capacitor. These are frequently used by the car guys. Simple to fabricate using a Radio Shack capacitor and a 3" extension.


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