Spektrum

Old 04-26-2005, 03:15 PM
  #751  
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sorry wrong thread
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Old 04-26-2005, 03:31 PM
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Originally posted by alien too
Will Spektrum work with KO Propo Mars R?
Yes
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Old 04-26-2005, 03:46 PM
  #753  
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Originally posted by Boomer
Guys - just cut the wire to 3.6" and be done with it.

This is a topic that has been discussed on the ARL boards for forever. ARL, for those who don't know, is the amateur radio body. If anyone around here would know more than they about practical usage of radio, antenna, etc. I'd like to know who it is.

The crimps, the coils, etc. are there to reduce the physical length of the actuall antenna assembly, not the length of the antenna WIRE.

Let's look at another from hyperlinktech, shall we?


From this, you'd think that the little coil in there is to increase signal strength, etc.

Until you look at the physical size of the antenna. This is a 6" antenna as compared to 10" for the one with the dual crimps. Basically, there is about 4" of antenna that is coiled up to shrink it's length from around 10-11" down to 6".

A longer antenna (lower harmonic) for this is going to be 21" (used for higher gain antenna or marine or places where length doesn't matter so much) - and you can see THOSE there too.

{{sigh}}

This is basic EMF theory. The length of the antenna wire must coincide with a harmonic of the wavelength of the signal in order to get optimal reception. It's as simple as that.

for a 2.4GHz frequency, the wavelength is just over 4" (thus the length of the antenna being 8" is 2x the wavelength which is normal). You could likely use 4.whatever (full wave) and would work great. However, why do that when you can use the 3.6" and be just as good.

the 3.6" antenna length is the 3/4 wave harmonic and is one of the ideal lengths.

Please note - I used a straight 2.4GHz for calculations - I did not get the exact frequencies within that range so numbers are somewhat approximate.
WOW !! didnt expect all this just trying to help a guy out All I know is that what I did looks clean and I dont glitch bottom line. The track I run at is 120 feet by 80 feet. not flying a plane so as long as i have no glitches in that area Iam a happy camper ( oh ya and dont have to worry bout crystals anymore )
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Old 04-26-2005, 04:39 PM
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you betcha, the bottom line is if it works, no worries. And it does look cool
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Old 04-26-2005, 04:53 PM
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Originally posted by nimble
you betcha, the bottom line is if it works, no worries. And it does look cool


but I cant take the credit for it Scott Welte at 4 funn hobbies showed me that
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Old 04-26-2005, 06:34 PM
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Originally posted by Boomer
It doesn't take a big cap, a small one works just fine....
I'd like to add that the size of the capacitor probably varies with the combination of ESC and those elements drawing power from the BEC.

From my testing using a Quantum Comp 2 and the KO Propo 2343 servo, I required greater than a 2200 microfarad capacitor in order to not have my Spektrum unit reset when moving the steering wheel rapidly.

3200 microfarads seemed adequate to keep the receiver from resetting... but even that might not be enough to handle the absolute maximum power requirements on the track.

I'm going to stick with the recommended 4700 microfarad cap. It'll be a pain in the ass to fit it into my car... but that's all that can be done.

Remember to try to find a 16v, 10v, (or even perhaps 6.3v) rated capacitor... typically the smaller the voltage rating, the smaller the cap.
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Old 04-26-2005, 06:37 PM
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I would think you would have no problems with that, your receiver pack should be able to deliver all the amperage you need. The capacitor fix is for speed controls that can't deliver enough amperage for the newer servos.
I was having problems with my spektrum completely cutting out at full throttle and driving itself into the wall at full speed , and I started thinking that it might be my esc not supplying enough power to the receiver under high load, and then it has to try to find the signal again once it cuts out so there isn't much chance of regaining control. Has anybody else has this kind of problem?
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Old 04-26-2005, 07:28 PM
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I guess I'll have to do better at not misspelling. . .
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Old 04-26-2005, 07:39 PM
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Originally posted by TeamPink91
I was having problems with my spektrum completely cutting out at full throttle and driving itself into the wall at full speed , and I started thinking that it might be my esc not supplying enough power to the receiver under high load, and then it has to try to find the signal again once it cuts out so there isn't much chance of regaining control. Has anybody else has this kind of problem?
You're correct. As a quick fix, install a 4700micro-farad capacitor to the Spektrum tranceiver (aka: receiver). This will help stabilize the BEC voltage during high load conditions (as with digital servos or ESC's with weak BEC voltage).

My Spektrum has worked flawlessly since getting the new software. The simple conveniences were well worth the $160, especially at the big races like the 'nats.

Another combination to add:
  • Novak GTX
  • Futaba S9550 (digital)
  • works in stock, 19T, and Mod touring, indoor carpet and outdoor asphalt
  • 4700mF cap
  • antenae tucked inside the body
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Old 04-26-2005, 07:41 PM
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Originally posted by TeamPink91
I was having problems with my spektrum completely cutting out at full throttle and driving itself into the wall at full speed , and I started thinking that it might be my esc not supplying enough power to the receiver under high load, and then it has to try to find the signal again once it cuts out so there isn't much chance of regaining control. Has anybody else has this kind of problem?
i had this problem on my system when I first purchased it. I sent it back and was told that they re-programmed the tx module and sent me a new rx.
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Old 04-26-2005, 08:07 PM
  #761  
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Originally posted by Bob Nilsen
I'd like to add that the size of the capacitor probably varies with the combination of ESC and those elements drawing power from the BEC.
Could be, Bob.

I found that a 470 microF cap worked fine for me, but it wasn't the servo that was causing my problem. It was only at the "stab" of the throttle that I was resetting. . .so I only needed to flatten the voltage curve a little.
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Old 04-26-2005, 10:47 PM
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This appears to be amore of an issue for people running 6v servos as opposed to 7.2v servos with a fly lead...

I think the increased current draw of the 6v servo through the BEC may be the isue...

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Old 04-27-2005, 02:19 AM
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I'd like to add my 0.02 to the antenna discussion.
If I remember correctly from school. Antenna wire works best when it's aligned to the transmitter, and it has to be full length of the transmitted wave to get perfect reception. They're least effective (but most consistent on a moving vehicle) when at 90 degree angle to the transmitter (like straight up). Coiling the wire makes it think it's a bit shorter, but it's so little that it hardly matters. So the solution is of course to lay the wire down lengthwise and only drive straight away from, or towards you.
I'm not going to start discussion of how the length of the transmitted wave changes when moving throught different materials. Air and Vacuum come to mind, the wave gets slightly shorter when traveling through air compared to vacuum.
Cut the wire to whatever length you feel comfortable with, splice it back to gether if you start experiencing trouble.

I don't have the manual. Does it say minimum 3.6 inches from the case or from the printed circuit board. If the 3.6 is a holy number then it should be from the circuit board, if it's from the case then the wire is longer than 3.6 because there is wire inside the case.

For the stopping of car. Don't use capacitor. Throw away that too expensive too high torque/speed servo (you can also send it to me ) or replace the ESC with something that delivers more juice to the receiver. EOR.

Last edited by andsetinn; 04-27-2005 at 02:25 AM.
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Old 04-27-2005, 05:13 AM
  #764  
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Well I am NOT HAPPY with the service I am gettting (not getting). I sent in a Module and reciever on Feb. 24 and have yet to get a replacement/ reprogrammed anything. I have called about 5 times and get the same BS. Horizon keeps telling me that they are out and that they are back ordered. Well my LHS has ordered about 4 systems in the past 2 months and had no issues with BO's! Horizon is saying that it will be next month before they get any. To be sent out as replacements. Hobby shop BO's are being done BEFORE PAID customers with problems are delt with!

I have read that the M8 system will not work on the new M11. So I calle dAirtronics to verify. I was told that is true. so now I have had a system for 2 months that I haven't even had in my hands. But not only that by the time I get teh system I will have a radio that it can't be used on!

Sorry but I had to vent on this one!
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Old 04-27-2005, 06:05 AM
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imprsme,

Have you spoken to John Adams at Horizon...he is THE contact point for the Spektrum equipment. Call the regular Horizon # (orders), and ask for John - he will help you out.
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