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RE: Official T-rex 450 XL SE Thread - 10/6/2006 10:32:34 AM   
don_87


 

Posts: 223
Joined: 12/26/2005
From: Markleysburg, PA, USA
Status: offline 		Cool, I have a Kenwood TS-450s.
Been into radios for years. 11 meter though.

(in reply to Karyn)
       Post #: 351

RE: Official T-rex 450 XL SE Thread - 10/6/2006 11:01:53 AM   
Karyn


 

Posts: 276
Joined: 4/13/2006
From: Lincoln, UNITED KINGDOM
Status: offline 		Hi Don

I have the TS-850sat, though it's mostly used by my bf. My interest atm is ex-military radios.


Getting back on topic... The direction your antenna is pointing is also a major factor in how well it works.
There is this thing called polarisation which put simply means that two antenna standing vertically will work well together, or two laying horizontally will work well, but one vertical and the other horizontal will not work.
In reality you will get signal reception, but the signal strength will be greatly reduced and the effect will be more pronounced as the distance between your TX and your model increases.

For people flying 3D where the model, and hence the antenna, is changing orientation constantly it is actually less of a problem than for beginners taking their first hovering lessons. Imagine yourself standing with your TX antenna safely pointed skywards so you don't take anyones eye out with it, this is the optimum position to get a good radiation pattern into the sky where your heli is (should be...) but now think of the antenna possition on the heli... It's normally layed flat along the line of the skids.

I know there's not alot that can be done about this due to the size of RX antennae (unless you're using a Spectrum radio), but bare in mind that if you start suffering from glitches, it is not always a fault in the heli or radio. It could simply be low signal strength due to "cross polarisation" of the two antennae. Try turning slightly, angle your tx down a little, or move the heli a little... NEVER point the TX antenna directly at your model, the radio energy comes from the sides, not out the end...

< Message edited by Karyn -- 10/6/2006 11:06:27 AM >

(in reply to don_87)
       Post #: 352

RE: Official T-rex 450 XL SE Thread - 10/6/2006 12:54:38 PM   
linkadrip



Posts: 1370
Joined: 3/17/2006
From: Tehachapi, CA, USA
Status: offline 		Well JD that is one awesome looking heli you have there you said that it was a trex 450XL looks like you upgraded it to the maxiumum. but i like it. Completely carbon fiber. I can see from the pictures that the gyro is mounted in the bottom under the boom in the center. seems like a logical place. Perfect right were the CG is. Cant wait to start my new one. I'm wondering were the speed control is and the receiver. How does it fly? I just may copy yours i'm always intrested in trying something different if it works better.

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RE: Official T-rex 450 XL SE Thread - 10/6/2006 1:18:32 PM   
linkadrip



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From: Tehachapi, CA, USA
Status: offline
quote:

ORIGINAL: Karyn

quote:

ORIGINAL: linkadrip

Well i received the Spectrum DX6 Radio System today ... ... i was amazed at how short the two anttenes are on the RX i can see why its not desighned for larger air craft.


The size of your antenna bares no relation to the size of your model.
Outside of RC I'm also a radio ham so this is my specialist subject...

Antennae are part of a tuned circuit in the radio, both TX and RX, and must be a very specific length to work efficiently. RC transmitters are not powerfull enough to do any self damage if the TX antenna is the wrong length, hence the reason you're able to do a range check with the antenna down. Try that with most ham radio gear, even with CB, and you'll quickly fry the output amplifier.

The antenna on the RX is just as critical to get good reception. It's one of those cases where bigger does not always mean better. The antenna length must match the frequency that you're trying to recieve, the closer the match, the better it will work.

For complex reasons I won't go into here, the wire antenna on an RC RX should be 1/4 of the wavelength. For us in UK on 35MHz that means over 2m long... and even for those on 72MHz it should be over 1m long. Tricks are done in the electronics inside the RX to make the shorter antennae work, but it is not as efficient as it could be.

Now move up in frequency to the spectrum radios that use the 2.4Ghz band, same as WiFi networking, Bluetooth, etc. a 1/4 wavelngth antenna is only 3cm (1 1/4 inches). So even though it may look small and pathetic, it's actually more efficient because it can be the correct size for the frequency it is designed to recieve.



Kryn
Well that explains alot there about why the antennas are so short in length. I think its great though now wont have to worry about a long old wire getting tangled in something. i had a friend a long time ago do that to an RX on an Airtronics XL2p Car Radio system he cut the wire down two about two inches and couldn't figure out why his car would go a few feet and then go out of control i told him cause he cut the antenna on the rx and ruined it. i Had no idea at the time that he had ruined the RX tried to put the wire back on and it was never right again. Learn something new everyday.

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RE: Official T-rex 450 XL SE Thread - 10/6/2006 4:18:30 PM   
consultjdm


 

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From: Canyon Country, CA, USA
Status: offline 		Linkadrip,

The speed controller is the align ESC with the radiator, its on the Left side (sticking out from the canopy) and the DX6 Receiver is on the Right side up front.

Those are the rubberized landing skids (blue) I really like them.


Yes the whole heli is either carbon fiber or aluminum. Its a custom frame (RC-expert carbon frame- its super thick). The horizontal stabilizer is the same shiny carbon as the sides and vertical stabilizer but it never shows up good in the pictures. Custom aluminum head and tail assy.
This bird flies incredibly. Super fast and stable. Solid on the ground during spin up. Never breaks. If you said - I want the perfect heli - this is just about it in this class. I am totally happy with it.

JD

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       Post #: 355

RE: Official T-rex 450 XL SE Thread - 10/7/2006 12:44:54 AM   
linkadrip



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From: Tehachapi, CA, USA
Status: offline 		Consultjdm

If you could possably take some picture of how you have your ESC and receiver mounted on your heli that would be great. I neverheard of rubberized landing gear are they metal with a rubber coating on them. like a wrench has a rubberized grip? I will have to look at helihobby and see if there are any on there web site. I'm wondering about the frame on the new TRex450XL Se if it is this carbon fiber type of frame. It says its carbon fiber but it doesn't look very thick.


i can kinda see how you have them mounted buy the pics you posted ,but wanted to see up close how you have the wires routed and how the receiver and esc are attached to the frame.

i'm sure the frame i'am getting with the new TREX isn't the same and may be a little different but i like how clean yours looks and if i can want to try and set it up in the same fashion.

I'm definetly going to have to get new landing gear the ones pictured that come with the TREX look like black cheap plastic.

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< Message edited by linkadrip -- 10/7/2006 12:53:57 AM >

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RE: Official T-rex 450 XL SE Thread - 10/8/2006 1:52:23 AM   
consultjdm


 

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No, they are a rubbery landing skid, no metal. I like them.
I got them at helihobby.


I will try to do more pictures tonight.

JD

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RE: Official T-rex 450 XL SE Thread - 10/8/2006 2:54:30 AM   
consultjdm


 

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Im a terrible photographer,.

Here are more pics.

JD

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RE: Official T-rex 450 XL SE Thread - 10/8/2006 2:57:56 AM   
consultjdm


 

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Status: offline 		A couple more pics.

The ESC is held on with wire ties and the RX with two sided tape.

JD

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RE: Official T-rex 450 XL SE Thread - 10/8/2006 11:33:23 AM   
linkadrip



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Thank you the pictures are perfect. Seems that you are a very good photographer. There clear and show all the wiring routing. That is great. Everything is clean and mounted were nothing is hanging out. Looks great, Thank you very much my Trex is suppose to arrive this tuesday on the 10th according to UPS. So i cant wait to get started.

Thank you
Very much Appriciated
PW


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RE: Official T-rex 450 XL SE Thread - 10/9/2006 1:59:11 AM   
consultjdm


 

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Im very excited for you. you will love it.

JD

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RE: Official T-rex 450 XL SE Thread - 10/10/2006 7:54:09 AM   
linkadrip



Posts: 1370
Joined: 3/17/2006
From: Tehachapi, CA, USA
Status: offline 		Well it arrived a day early. Looks like i have my work cut out for me. So i took some pics of it now and then i will take some of later after its built say its about 30 minutes to assemble but i think i will take my time and take a couple of hours or so. But i'll post more pics after i'm done or if i happen to run into a snag along the way still waiting for the gyro to arrive but i can put most of it together.

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RE: Official T-rex 450 XL SE Thread - 10/10/2006 4:04:30 PM   
consultjdm


 

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Status: offline 		Linkadrip,

More like 8 hours if your quick I think. LOL

Which one is that? 450 SE, I didn't know they came with a pure white body.

JD

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