Use The Force Luke....

[alexchen86]

Well I was pulling out my Futaba R603GF RX out of my SC10 4x4 last week selling the rig as a roller but the double sided tape I used was too strong....yup 3M waterproof heavy duty is not a good idea

I always use the same 3M tape since on my crawlers I build them to be waterproof so the ESC is waterproofed and I need something strong to adhere to it.

Long story short while taking out the RX with a small flathead and working my way around it slowly somehow the flathead blade got jammed on the RX wire and cut it right open right where it attaches to the case!!

Searching around apparently Futaba sells these replacement RX wires for like $3 a pop. Is this the only way for me to repair it? Or can I solder some thin gauge electrical wire and shrink wrap it?

Here's the damage:


Thanks for any help you guys can think of!!

[Docwolf]

you can solder that wire back in, i have like a 3 inch solid copper wires (cat 6 network cable) on mine, in a box, surround with electronics. i get no interference or loss if signal, 2.4 is pretty forgiving.

[alexchen86]

Cool...I work for a tech company so we have a ton of wires I can use RJ11, RG6, CAT5, CAT6....which one should I use? The original Futaba silver RX wire I have no clue what it's made of.

[Docwolf]

as long as it conducts power, your good. i used cat 6 because I have an ass load of it laying around. most 2.4 antennas like the ones on your router are just copper strand, nothing special, i would assume the same for the RX. the trick will be opening the housing with out breaking it. unless those screw together.

[Olle P]

Do check if the antenna cable is single wire or, as in the transmitter, a coaxial cable.

You don't need any additional wire though.
Just remove the remains from the board, strip a short bit of the antenna cable and solder the two wires (core and shield) onto the correlating points on the board. That the cable is ~1/4" shorter than before makes no difference, since the actual antenna part of it is only 26mm at the outer edge.

[ik632]

[Master Yoda]
Pull too hard, and antenna you will cut off mmmmm
[/Master Yoda]

[alexchen86]

Originally Posted by ik632

[Master Yoda]
Pull too hard, and antenna you will cut off mmmmm
[/Master Yoda]

Ahh the jokes lol...this is what happens when a bunch of dudes get together with too much Hollywood and too many toys...welcome back to 2nd grade guys. Sometimes I wonder it's a miracle I can rub my head and my belly at the same time!!

And they call me an "I.T. Director" at work. Lol.

[ik632]

I couldn't help myself. It was just begging for words of wisdom from Master Yoda.

As long as the wire is the same length when you're done you're good. I've seen other people use CAT5 cable before as well too like Docwolf.

[Olle P]

Originally Posted by ik632

As long as the wire is the same length when you're done you're good.

The length is (for all practical purposes) irrelevant, as it's only the outer 26mm of it that is the actual antenna.

Alex can shorten the wire by 2" or more and still have full functionality!

[ik632]

I knew on the 2.4ghz receivers that only the end was the working part of the antenna, but I was always under the assumption that the impedance of the wire going to the end also affected things.

I've learned something new today, thanks.

[Docwolf]

The only time length gets involved is when you are trying to improve coverage, like with a wifi connection. For rc, it is not important.

[Olle P]

The length of the actual antenna itself is very important in order to get a good transmission. With a wavelength of only ~12cm it's not good being 0.1 cm off.
On my other RC car, sporting a 27MHz radio, I use a 70 cm antenna! (~1/16 wave).

[Docwolf]

2.4 ghz is a far more forgiving frequency. In the world of rc rock crawling, I stand behind my previous statement. 27 and 49 mhz are more prone to interference simply due to the way in which the "signal" is transmitted across the spectrum. 2.4 uses a technology that for lack of a more layman term, segregates the data and thus avoids drastic interference. You also only need 1/4 of the wave with 2.4 to get a good signal.

[Olle P]

Originally Posted by Docwolf

... You also only need 1/4 of the wave with 2.4 to get a good signal.

... compared to the 1/32 wave length antennas normally used for 27MHz...

[Docwolf]

The antenna on your fm controller is roughly 1/8 the wave. The antenna on your digital controller is roughly 1/4 of the wave. 2.4 is a much more compact and shorter wave.

[Olle P]

I'm talking reciever antennas.
2.4 GHz use 26 mm => 1/4 wave.
27 MHz typically use ~340 mm (tube length) => 1/32 wave.

[Docwolf]

the same math applies, using your figures.
2.4 wave height = 104 mm
27 wave height = 10880mm

2.4 has a smaller, tight wave that travels further with out degradation or deterioration and carries for more information with less interference and data bleed.

[unknownhero55]

just have to say holy shit thats a lot of tech!!

[alexchen86]

Wow...that is a lot of tech! Lol...if I use this RX on another scaler rig I should be fine...I think the antenna only affects range not functionality. Correct me if I'm wrong.

[Olle P]

Originally Posted by Docwolf

2.4 ... travels further with out degradation or deterioration ...

No it doesn't. It's a well known fact that low frequencies travel further than high frequencies. If you go down to the kHz bands it's even possible to have the signal bounce off the clouds to reach well beyond the horizon.
I bet the SNR at one mile from the transmitter is better for 27 MHz than it is for 2.4 GHz, given the same output power.

Originally Posted by Docwolf

... and carries for more information with less interference and data bleed.

That comes from the way the information is encoded onto the carrier wave, and not from the carrier frequency.
Also, as was the point of my previous post, using a 1/4 wave receiver antenna makes for a lot better reception than if using a 1/32 wave antenna.