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Old 03-09-2012, 06:23 AM
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Flynstuff
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Default On board Data Terminal

I was informed by a good source that on board Turbine data terminals can cause radio issues.
I'm looking for more information on this.

My data terminal is in the nose of my F16 and the RX is under the aft part of the canopy.

Anyone have experience with this??
Old 03-09-2012, 06:36 AM
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schroedm
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Default RE: On board Data Terminal

It would seem very odd to have something called an "On-Board" data terminal that causes RF issues?? [X(]

Old 03-09-2012, 07:26 AM
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joeflyer
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Default RE: On board Data Terminal

Read the owners manual that came with your turbine. All the ones I have advise against mounting the data terminal on board for the reason stated.
Old 03-09-2012, 07:51 AM
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C185Pilot
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Default RE: On board Data Terminal

Evojet has a minature data terminal specifically made to be mounted in the airplane. We have flown them for hundreds or hours with no problem. Fantastic item.
Old 03-09-2012, 08:11 AM
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Dr Honda
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Default RE: On board Data Terminal

It's probably for liability, and let's face it... most of the old data terminals were huge. BUT... if your unit says to not leave connected, and in the model, then why take a chance? Even if it doesn't cause interference... the ECU has to sync, and send data to the terminal. That could cause a lag in performance. And finally, you can't look at it while it's flying, so why add the weight, and power draw??

Just my 2 cents... take it for what it's worth.
Old 03-09-2012, 08:21 AM
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Default RE: On board Data Terminal

Oh! If you're talking about the regular ground terminal then no, I wouldn't put that in the model (extra question - why would you?) but as you are asking about on-board terminals then yes, I used them in several models with zero problems.
Old 03-09-2012, 08:26 AM
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Default RE: On board Data Terminal

Needed a little nose weight in the aircraft and had an extra Terminal that had a cracked case so I figured what the heck.

Not knowing that there might be an issue I installed it. Thats why I'm asking. I haven't seen any lag or issues in performance. It was just brought to my attention that it could cause RF issues so that's why I was asking.
Old 03-09-2012, 08:34 AM
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Default RE: On board Data Terminal

We've flown several jets with an onboard data system that we developed that interrogates the JetCat ECU for the same data that a data terminal does and telemeters it to the ground. We've never had any interference problems with Futaba and Spektrum 2.4 GHz receivers. Also, I believe that EagleTree has an add-on that does the same thing.

Back in the 72 MHz days, you had to check carefully that any onboard processors would not cause interference problems - mainly because their clock speeds were right around the 50-100 MHz range. Now that we've gone to 2.4 GHz, the issue has mostly gone away.

Assuming you're on 2.4, do a thorough range check and if is OK, I'd fly it.

Bob
Old 03-09-2012, 08:37 AM
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Flynstuff
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Default RE: On board Data Terminal

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Old 03-09-2012, 08:46 AM
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Default RE: On board Data Terminal

I would not be too concerned about interference problems with that, but I do wonder if having the data terminal connected like that can cause problems with the ECU should the connection get "flaky" or if the data terminal software crashed.

The system we developed was for a Jetcat ECU and we designed it so that it just sent a single message to request turbine run data, so there was no way that it could accidentally send messages that are used to "control" the turbine over the throttle signal its getting from the RX (as the normal Jetcat data terminal can do). That's a low probability scenario, but I'm not familiar enough with the Jet Central ECU/data terminal setup to say...

Bob
Old 03-09-2012, 09:08 PM
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Default RE: On board Data Terminal

They reduce range. Simple test: Plug it in, and perform a range check. Measure your distance. Then unplug it and do a range check. Measure your distance. Almost double the range when it is NOT plugged in. Hazard. Don't do it Jeff!

Shaz
Old 03-09-2012, 09:19 PM
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Default RE: On board Data Terminal

I will probly just remove it at this point. Dont want to take any chances.

Thanks for all the info guys.
Old 03-09-2012, 10:38 PM
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Default RE: On board Data Terminal

Jeff what you have is huge compare with the one from evojet. we have this evojet unit installed on a carf flash with g-booster for 4years with no problem, i dont know however with the terminal you have. i wouldnt use it either in your case.
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Old 03-10-2012, 05:15 AM
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Default RE: On board Data Terminal


ORIGINAL: sskianpour

They reduce range. Simple test: Plug it in, and perform a range check. Measure your distance. Then unplug it and do a range check. Measure your distance. Almost double the range when it is NOT plugged in. Hazard. Don't do it Jeff!

Shaz
Really, even with 2.4? Is that with Spektrum or Futaba? I'm wondering if its noise somehow being coupled into the satellite RX connections?

Bob
Old 03-10-2012, 05:45 AM
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Default RE: On board Data Terminal

One last thought.

On most systems (JetCat, Xicoy) the terminal is it's own entity. There is a processor, and it can change system settings. AND... in the case of a RAM... it can start and stop the engine. The only system where the data terminal is "Inert" is with the AMT engines. It can't change anything, and it simply reads the output of the ECU.

On most of the systems... if there is a glitch in the data between the ECU and Data Terminal... bad things could happen. I'm sure it's a very slight risk... but it could happen.

As I said before... why take the chance, when you can't see it anyway??
Old 03-10-2012, 06:27 AM
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Default RE: On board Data Terminal

Sounds like the consensus is to remove it. Nice job making the frame to mount it. Seems a shame to have to undo it.
Maybe you can use it for a battery compartment instead.
Mark
Old 03-10-2012, 07:57 AM
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Default RE: On board Data Terminal


ORIGINAL: rhklenke


ORIGINAL: sskianpour

They reduce range. Simple test: Plug it in, and perform a range check. Measure your distance. Then unplug it and do a range check. Measure your distance. Almost double the range when it is NOT plugged in. Hazard. Don't do it Jeff!

Shaz
Really, even with 2.4? Is that with Spektrum or Futaba? I'm wondering if its noise somehow being coupled into the satellite RX connections?

Bob
Bob I swear it's true. Range checking my F22 last year I couldn't figure out why she kept losing signal after only 20-25 paces. Chatting with a rep same day as I was adjusting turbine deceleration settings to compensate for our higher altitude. I mentioned it off-hand that it didnt matter since my range check wasn't looking good. He asked if my HDT (identical to Jeff's unit - the Xicoy ones) was on board. I said yes, he said "unplug it". I did, it gave me 90 paces on the range check immediately. My radio at the time was a JR 12X. I now fly Futaba 12Z. Only reason I had left HDT plugged in was to see what readout it would say as soon as turbine flamed out when i went out of range. Anyways, interesting experiment, never to happen again. Enough reasons somethingcan go wrong let lone have a user-induced lock-out on board...

Shaz
Old 03-11-2012, 04:11 PM
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Default RE: On board Data Terminal

I first flew my Boomerang Intro in Texas for 9 flights then shipped it to Denver. My first time to the field in Denver my range check was 1/2 what I expected. After a little while I realized I had the Data Terminal still plugged in. Removed it and range check was normal. The radio was CH 55 on 72MHZ. Have not tried same thing on 2.4GIG yet.
Old 03-23-2012, 04:49 PM
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Default RE: On board Data Terminal

So, what would you all say about leaving the Jet Cat Mini GSU installed in the plane?

Old 03-23-2012, 06:04 PM
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Default RE: On board Data Terminal

They are designed to be left on board and work real well.
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