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-   -   Spektrum (https://www.rctech.net/forum/radio-electronics/63411-spektrum.html)

thunderbt3 01-17-2007 06:29 PM

Capt. Micro, I've experienced the signal cut-out before. Once when I was running my Revo, the throttle would seem sluggish. This was on the Spectrum Pro system with the stock Pro RX. The second time, I was running my 1/18 car and the car took off and smashed into a curb. No damage tho except for some srapes on the bumper. I believe the cause of that take off was that my TX antenna was folded down and not sticking up so the signal might have been blocked buy the transmitter :confused: . I dont remember if it was the same case for the Revo. I have a JR/KO Z-1 and they both happened when the cars were on the right of me.

AdrianM 01-17-2007 06:58 PM

Are you guys sure you set the fail safe properly? You can test it by turning you radio off.

I set roll throttle in my 1/12th car so it rolls forward at neutral trigger. Before races i turn my transmitter off so car goes into fail safe and sits still. My fail safe setting is full brakes and centered steering. We the grid is set I turn my radio on and race.

InspGadgt 01-17-2007 07:19 PM

I had the original low voltage issue with my first spektrum recievers. Back then using the external capacitor worked to fix the problem. Later we changed track locations to an indoor track and started running 4 cell 1/12h. I bought the new micro spektrum reciever and had no problems with it running on 4 cell without the capacitor. That track closed down so now we are back to our original outdoor location and my car is glitching again with the new micro reciever, even though it has the capacitors internally. I initially thought it was a problem with my transmitter so I bought a used one just like it and the problem still exists. So it seems even the new versions can still have a low voltage issue given the right circumstances. Now I really don't want to be using a RX pack or external capacitor to fix the issue so I rigged it so the RX is powered directly off my 4 cell pack which should solve the issue...but I'd still rather not have to do this. I'm considering switching to the Futaba system because of this.

coons88 01-17-2007 07:45 PM


Originally Posted by AngryAsian
Coons... The aerial, actually ALL aerials are design to sync into a certain wavelength signal. To do so, they need to be of a certain length. This is why the aerial lengths on different recievers is different. Now, some aerials and systems will have fancy winding patterns, or electronics to mimic the full extended length in a compact package.

In RC, the wavelength is small enough that a full length antenna is best.

The Spektrum even though is is a 2.4GHz system relies on the same principle. In order for the reciever to get the best signal, the antenna length must correspond to a multiple of the transmitted wavelength.

So - it's either full length as it came from the factory, or 3.6inches from the board. Preferrably running the aerial straight up. Hence the specific length.

Running the aerial at any arbitrary length will result in a weak signal being recieved.

The guy from spektrum said this tough:


The antenna wire can be cut down to 3.6" minimum length. If longer it should not have any problems.

RCGaryK 01-17-2007 09:15 PM


Originally Posted by InspGadgt
I had the original low voltage issue with my first spektrum recievers. Back then using the external capacitor worked to fix the problem. Later we changed track locations to an indoor track and started running 4 cell 1/12h. I bought the new micro spektrum reciever and had no problems with it running on 4 cell without the capacitor. That track closed down so now we are back to our original outdoor location and my car is glitching again with the new micro reciever, even though it has the capacitors internally. I initially thought it was a problem with my transmitter so I bought a used one just like it and the problem still exists. So it seems even the new versions can still have a low voltage issue given the right circumstances. Now I really don't want to be using a RX pack or external capacitor to fix the issue so I rigged it so the RX is powered directly off my 4 cell pack which should solve the issue...but I'd still rather not have to do this. I'm considering switching to the Futaba system because of this.

What ESC are you using out of curiosity?

RCGaryK 01-17-2007 09:17 PM


Originally Posted by AdrianM
Are you guys sure you set the fail safe properly? You can test it by turning you radio off.

I set roll throttle in my 1/12th car so it rolls forward at neutral trigger. Before races i turn my transmitter off so car goes into fail safe and sits still. My fail safe setting is full brakes and centered steering. We the grid is set I turn my radio on and race.

:nod: :nod: :nod: :nod: :nod: That could very much be the cause, great call Adrian.

Capt.Micro 01-18-2007 05:05 AM

The fail safe may be part of my problem but there is definetly something else going on as well. As I mentioned, in both incidents, I has a fresh 6 cell pack intalled, therefore I doubt there is a low voltage issue. Also, when the car took off it went to full throttle and it was only 10-15 feet away from me. Unfortunetly, I think this receiver is going on the shelf. I cant afford to fry another $150.00 speedo.

RCGaryK 01-18-2007 06:35 AM

It's not necessairally a Low Voltage issue. It could simply be a loss of signal for some reason which would have caused the receiver to go into fail-safe mode. I'd say send your receiver and module in just to have them checked out. Now with the QC2, I've always had to run a power cap on the ESC, since the BEC output is lower on that speedo. However, I run both the HB and KO versions of the VFS-1 without any issue. Make sure you set the voltage in ESC to 4.0v thru either the handheld programmer or the PC interface.

Boomer 01-18-2007 08:18 AM


Originally Posted by coons88
The guy from spektrum said this tough:

I understand, however if you're asking a technical support guy it's quite probable that he does not know the physics of it or if it actually works. He may know what he's been told and, as we all know, it's easy to interpret the instructions as he has stated them - and he would be wrong.

Antenna lengths work off harmonics of the wavelength - meaning specific lengths.

Here's a quick reference - http://www.electronics-tutorials.com...s/antennas.htm

or google antenna length and you'll find a wealth of information. You'll find that Ham radio operators have this stuff pounded into them.

Antennas can WORK if they're the wrong length. . .but not well and often barely.

thunderbt3 01-18-2007 08:57 AM

Im pretty sure I have the failsafe set correctly. I have it at neutral so when the transmitter shuts off, the car sits still. The glitching only happened to the right side of me so I think it was my own fault for not rotating the antenna up so it was sticking out from behind the transmitter.

poop 01-20-2007 06:38 AM

hi all, i apologise if this has been covered before but here's my question:
i saw some fellow racers relocating the spektrum tx antenna to fit into the original antenna spot on a ko helios. i was wondering if this mod will void my 1 yr warranty? it does look a lot neater than having the antenna in the back though :nod:
cheers.

RCGaryK 01-21-2007 04:11 PM


Originally Posted by poop
hi all, i apologise if this has been covered before but here's my question:
i saw some fellow racers relocating the spektrum tx antenna to fit into the original antenna spot on a ko helios. i was wondering if this mod will void my 1 yr warranty? it does look a lot neater than having the antenna in the back though :nod:
cheers.

Yes, it will

2-Bad 01-21-2007 04:14 PM


Originally Posted by RCGaryK
Yes, it will


You "kill-joy" Gary... (just joking) :lol:

RCGaryK 01-21-2007 04:25 PM

That's Me! :lol: I'm just the messenger, but happy to help if and when I can

RCBuddha 01-22-2007 05:38 PM

Gary,

So LRP is the only manuf. that seems to have a BEC issue with the spektrum system?

I don't mind running a seperate battery for the receiver (weight is not an issue, but size is), but can anyone point me to those small receiver packs that I've seen on 1/12th cars?


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