Antennaes

[55psi]

Hey guys, just wondering, can u chop excess antannae wire so u can fit the cap for the plastic antannae tube/protector?
Or will stuff it up?

[Kenny T]

Don't cut the antennae, just coil it up .

[rocknbil]

. . . . the reason being that transmitters and receivers are tuned to the antenna length, cutting it may either render it nonfunctional or at the least shorten your range.

[TEM]

Theres a common misconception here of our radio antennas actually being "tuned". It's really NOT! As long as it's not ridiculously short, it will work fine. Make sure the sheathing is not spliced and the metal touches anything conductive!.... I always coil the antenna wire over a 3" long piece of antenna tube that hides underneath the body. I never get no glitching problems. But to be safe; sure, keep it as long as possible.

[55psi]

oh yeh, i forgot that u can pull the excess wire from inside the top tray :D
thnx TEM

[highroller]

I never cut the antenna wire, any excess is coiled around an antenna keeper (make one from scrap lexan) but it depends on the type of racing and track size as well. Oval wire may be inside of body (coiled around antenna tude) while on a large outdoor track it extends above and outside car like for offroad and touring cars with any excess coiled up and away from chassis. Check the amount of length that extends from the tube, measure and make the excess the make a keeper and coil the excess around that and feed the rest through the antenna tube with 1/2 to 1 inch extending out. Mount the antenna keeper to chassis or top of receiver or servo. Width and length can vary depending on amount of excess antenna wire.

[55psi]

what i did was that i pulled the excess wire from the antennae tube mount so that there was atleast a couple of mm showing on top of the tube, and the a coiled the rest inside my radio box with all the other servo wires

[rocknbil]

Originally posted by TEM
Theres a common misconception here of our radio antennas actually being "tuned". It's really NOT!....

Quote your resource. It IS tuned to the length, as quoted from several manuals, which I'll do my best to locate. They specifically state that the receivers are factory tuned to the receiver wire length and to never cut them.

If the receivers are not tuned to a specific wire length, why are different receiver wires different LENGTHS?

If you're right you're right, but let's see some facts.

[Lapster]

For my Novak recievers the Manual says you can send it back to the factory to get it re-tuned.

[TEM]

The antenna is good for a range of frequencies and what we operate on falls into this range. By "tunned", some R, L or C values are adjusted in the receivers circuitry to make the receiver respond to a more narrow range and also to adjust it so each "module" has a clean input and output signal between each other. I'm just too lazy to dig out my old text books to give a full an precise explanation.

But anyhow; the effective length of the antenna is not necessarily the length of the actual wire. I mean if you coilled the wire on the antenna tube or had a few inches dangling, or a inch to route from receiver to base of antenna tube; all these things change the effective length of the antenna.

so what I am really saying is, the receiver is tuned for the frequency range; and the antenna is just a suitable length for that range. I mean if you changed a crystal, does that mean your antenna is now offtuned to the receiver?

Could we also assume our TX antennas are tuned too? Then how come they make rubber ducky antennas for airplanes Tx's?

They tell you the antenna is tuned so it sounds better and for you not to cut it so there is less chance of interference so their brand remains more reputable.

Anyhow, try anything and see what happens. I've replaced my own antennas with a piece of wire I find out of my box. It works fine. Like I said before, I coil my antenna wire around a 3" long piece of plastic tube and it works.

[Lapster]

Where did you hear that?

[55psi]

so the longer the wire coming out of the reciever box is better?
so u shouldnt coil it up or anything?

[Lapster]

Whatever the reciever comes with is what you should keep. I coil all of my reciever wires up insde of the car to keep excess wire from comming out of the tip of the antenna tube. It is fine to coil it, just dont cut it.

[rocknbil]

Well I am "not" too lazy and will try to verify my sources this evening. I've been in this hobby for over ten years and everyone I've ever talked to, ever resource I've ever encountered, says specifically the antenna length is specific to the system. That is why when you go to replace a Futaba RX wire it's a different length than the Airtronics. If there's some real facts countering this - I'm all ears.

[InspGadgt]

The antenna is good for a range of frequencies and what we operate on falls into this range. By "tunned", some R, L or C values are adjusted in the receivers circuitry to make the receiver respond to a more narrow range and also to adjust it so each "module" has a clean input and output signal between each other. I'm just too lazy to dig out my old text books to give a full an precise explanation.

The reciever and antenna length are tuned to a specific frequency range. Differences in the internals of the reciever effect reception hence why a Novak reciever on 75mhz has a much shorter antenna wire then a Futaba reciever on 75mhz. Sure because it's tuned to a range of requencies instead of a specific there is room for error in the antenna length but it's not much and it's risky to even try it. It's just better overall not to shorten the wire as you may over do it.

But anyhow; the effective length of the antenna is not necessarily the length of the actual wire. I mean if you coilled the wire on the antenna tube or had a few inches dangling, or a inch to route from receiver to base of antenna tube; all these things change the effective length of the antenna.

Here your lumping two things together that are different that both effect reception. Effective length and effective height. coiling up your antenna wire isn't going to change the effective length of the antenna as much as it's going to change the effective height. So if you have a coiled antenna that's only 3 inches high it's still going to recieve better then a straight antenna that's been cut to 3 inches. This is why rubber ducky antennas and base loaded antennas work.