3.6 Inches is an exact length

EDITED DUE TO BRAIN FART

:D

The instructions say the following, "If desired, the antenna can be shortened (cut) to exactly 3.6" with negligible loss of range and in some applications the short 3.6" length will make installation easier."

It sounds like you need to keep it the stock length or cut it to 3.6 inches, no inbetween.

qwiglee I will take a pic on how i did mine and post it later on tonight. All my stuff is at the track so cant do it now :D

I for one am still not convinced of this product being fooll proof in the latest release. I just picked on up last weekend from a large hobby shop (Sh#%@ons) in SJ and was told it was from the latest batch. The system bound perfect to the transmitter and I thought all was fine and dandy until my first time out on the track. When my car made it's way to the back straight, it died and I yelled out dead car (no steering or throttle response) on the back straight before I got pummelled. As the turnmarshal grabbed my car and started walking back to me, I regained control. I thought it must have been a fluke so I rebound the system again in the pits and tried it again. Same results. Even walking away from my car in the pits (less than 100 feet) across the parking lot had the same results. Anybody else have this problem? My system is on its way back to Horizon.

I know it's been said again and again, but have you tried a capacitor?
I was having no troubles until this weekend, where I had the EXACT same thing happen to me as what you describe. My car worked just fine until a crash. It then started hitting the fail-safe every once and a while. After a short dead-car period, (around 5 seconds), it would come back to life. Very odd after having zero troubles with the system for weeks....

Turns out that I had stripped a few teeth off the servo in the crash, and while my servo still worked, it was exceeding the voltage threshold of the receiver while the servo motor was trying to force it's way past the messed up teeth on the servo gears. I put in a new servo and all was back to normal.

So I mention the capacitor to you because perhaps your BEC isn't feeding enough juice to the receiver to get the required voltage? A capacitor will help with this problem. But that's just a guess. Hope you can sort your troubles.

If the antenna is exiting the case at the top of the Rx and not the side then measuring from the case is close enough. The circuit board sits directly beneath the top of the case, so your 3.6 measurement will be good. If it is out the side then you have to take into account the case length to the hole. It must be cut as close to 3.6 as possible!

Exact means, well, exact. A millimeter either way is not going to make a big difference but remember that a millimeter is like 1/16" (roughly) so it needs to be right there. . .

As I posted earlier, this is because antennas need to be specific lengths because they pick up signals by resonating sympathetically - in other words, the signal causes the antenna to resonate which sends the signal through the antenna to the board. People seem to think that the TIP of the antenna is what receives the signal - it's the entire length.

It has to be certain lengths because those are harmonics of the main wavelength.

A 2 meter wavelength (Ham mobile radio) must have an antenna that is 2 meters long (full harmonic), 1 meter long (half or first harmonic), 2/3 meter long (1/3 or second harmonic), half a meter long (1/4 or third harmonic) or 1/4 meter long (1/5 or fourth harmonic). This is akin to touching a guitar string that has been sounded at the 12th fret (first harmonic) or the 5th fret (fourth harmonic I think - my guitar is at home. . .)

so - follow the directions! :D 3.6" exactly.

I had the exact problem you descibe........

Two things here - just because it is from the latest shipment does not "gurantee" that the software is current. I puchased 6 receivers and 4 out of 6 had old software. I know, the QC should have caught that - but it didn't.

Second item - one of my TX Modules (Futaba version) had the antenna not connected correctly internal to the module (per John Adams).

Now for the good news. Since John has serviced these units - they work flawlessly! Yes it has been an inconvenience to send them back to Horizon but John has been very quick and returned the units ASAP to me. It is really neat to not worry about freq conflicts, glitching or any other radio problems since being on Spektrum.

I have these units running offroad and onroad in 1/10 and 1/8 cars, buggies and trucks.

Just as Cartman said, you should try a capacitor.

Many electronics today are pushing the BEC of many ESC's - especially the digital servos. Not sure why the ESC's haven't upped the BEC voltage but. . .

I know guys that won't use certain ESC's with certain servos. I don't remember what they are since it didn't apply to me (thus, I didn't really care aside from the "really? wow, that's wierd. . .") This was using normal receivers (little blue Airtronics ones. .. you know).

so it's not just the Spektrums. they're just shedding light on a larger problem. With the higher capacity servos we're using and the higher drains we're putting on the BEC voltage, ESC makers need to step up. . .

The idea of the cap to help the BEC of the ESC would work ok, but Im using this Spektrum unit in a 5th scale car running 4 servos. 2 for steering and 2 for throttle and brake. Im sure John will take care of me just as he has done to the rest of you.

Listen to this man, if you do not believe go look up some 2.4Ghz home made antenna sites (as in wireless networking) - they are not cut to any old length.

My bad, I misread the info...

On the FAQ it doesnt say exactly.... Thankfully I havent cut mine :o

And even when you think about it the length is critical as its a tx module as well as an rx module..... brainfart when I posted...

:rolleyes:

Just the topic I m after. I have decided not to cut the wire but not sure if I still need to use a short antenna tube point up, even it its only 4 inches in length or it doesnt matter.

the thing I don't understand is why it need to be exactly 3.6" when you also have to consider every bend in the antenna. I understand that at 2.4, the bend have a great affect on the attenuation of the antenna, more then the length of the antenna. so if you look at say a 1/12 scale car where the antenna is wrapped around the upright antenna, would the length still need to be exactly 3.6"?

heres that pic