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Hitec Optima 9 Rx


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Posted (edited)

Fettling a model for a good mate but there are 10 servos and only 9 channels on the RX.

It's a large glider tug and has a choke servo on a ZDZ 95cc petrol engine, so we can do without that.

 

Servos are 2x elevator, 2x flap, 2x ailerons, a tow release, a throttle and rudder.

All well and good till we get to the battery input which shares the same as channel 9.

 

So first question is can I Y lead one servo (say tow release) and the battery into channel 9 port in the RX.

Second question is where does the second battery feed go (from a Graupner twin battery backer device) as Y lead on the battery feed (after the backer unit) defeats the safety of having twin feeds into the RX and there is no free port left on the RX.  Can I use the data port or not? 

Or do I Y lead another servo channel (1 to 8 ) with second battery feed into any other port on the RX?

Third question, can I Y lead the flap servos (25kg each) so drawing a fair amount of current when deployed 90 degrees for every landing. 

Will the RX pc board handle high current at 6 volts when both flaps are down for each landing through one channel?

 

TIA for any help.  And no, "choose another radio" is not a option for him!

John M

Edited by John Minchell
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Reading the manual the SPC port will power the Rx but not the servos. On a large model like this I would power the servos from a second battery through a BEC like this

20A 3S-12S LiPo Switching UBEC for £19.99 from 4-Max for example. The flaps can then use a Y lead, orientation of servos permitting. I would also have thought that the elevator servos could use a Y lead. 

 

Not that I have done any of this just what I have seen others do. 

 

Being here to learn hopefully a more experienced member will respond.

 

Steve

 

 

 

 

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SPC port only powers up the receiver side of the board, it does not power the servo outputs, so you can not use it for the OP's purpose.

 

Having used the telemetry sensors, the data port is probably not on the servo power bus as the sensor stations needed their own power supply.

 

Yes you can Y lead together the battery and a servo, one to the tow release, the other to perhaps the throttle.

 

I can not comment on putting 2 heavy duty flap servos on one Y lead. Is the plane too large for a set up that is being contemplated and you should be considering one of the power box type devices where the batteries supply the power box and servos take the power from this rather than direct from the Rx.

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2 minutes ago, PeterF said:

SPC port only powers up the receiver side of the board, it does not power the servo outputs, so you can not use it for the OP's purpose.

 

Yes that's what I said so a separate UBEC is used to drive the servos.

 

Steve

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John, good idea to Y lead on the flap channels, that way the flap servo current doesn't pass through the receiver.

 

The other option would be to use something like a Powerbox unit, MPX standalone Wingstabi with dual battery inputs or one of 4 Maxs power distribution units. Note the Powerbox and Wingstabi have servo matching options so you'd only need one aileron, elevator, flap channel from the Rx, but they would need programming ? and of course they are quite an extra cost.

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6 hours ago, EarlyBird said:

Yes that's what I said so a separate UBEC is used to drive the servos.

 

Steve

Yes, but when I started typing my response you had only put the diagram up, so I was responding to that. At the same time as I was typing you posted about the actual function of the SPC port and that got posted before I finished typing.

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Thanks for the replys gents - much appreciated.  I've also spoken to the importers and to Frank who was a great help.

 

So I can't use the SPC port to power the servos OK. 

I can Y lead any two servos with the Graupner battery backer output feeds one and two and then feed into any channel socket on the RX.

Best solution is to leave the choke servo on a flylead and set it for the first start of the day with an external battery and a servo tester then disconnect it for flight.

I do not have to only use ch9/batt as the only battery input.

Use all 9 servo sockets one for each servo, but Y lead the two backer feeds to the two flap servos, as they will pull the most current.

I can use any of the 9 channel sockets to input the power.

That will get it flying this weekend.   

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