Ge|atinousFury

2 questions.....I really appreciate the info I get from people here on these forums Thanks in advance for the help!!

1. Myself and my friend have just pre-ordered a couple of Savage SS's from our LHS and the kit doesn't come with a radio. We are both planning on getting JR XR2i or XR3i radios (whichever model we choose we'll still get the same model). Now, considering I know next to nothing (well, make that nothing) about radios, what are we gonna have to do (if anything) to be able to drive the trucks together without us picking up each other's radio signal?

2. My LHS informed me that if I want to add the reverse module for the Savage, it would require a 3rd channel on my radio, which the JR XR2i radio doesn't have. The guy told me that there's a $20 part that can let me use the reverse module by adding a channel or something like that. Considering the XR3i is $70 more than the XR2i, should I just get the XR2i with the optional part he is talking about or should I just go for the XR3i?

CHassan

My Feedback: (13)

From experience, get the best you can afford. If you can get a Radio with the 3rd channel do it.

As far as being able to run together, just make sure you get radios on different channels.

Ge|atinousFury

Any particular reason that the XR3i would be any better than the XR2i with the added $20 adapter?

Also, do JR radios come with receivers?? If not, can anyone suggest one for me to buy.....because I doubt that the Savage SS kit comes with one.

HabeebThe711Guy

i was kinda wondering the same thing as gelatinousfury: at the tracks theres so many people with controls rite how come none of them interfere with each other, the only channels i heard you can get different are 27 and 75 what about if you wanted to get a third or fourth party racing with you how do you do that?

CHassan

My Feedback: (13)

27 and 75 are the frequencies. In each frequency you have several channels (actually channels are just different frequency like 27.145Click here to see chart of the channels.)



Ge|atinousFury,
I've not used either radio, so this is just my personal opinion. I would rather buy a radio with what I need then to rely on a add on componet. To me thats just something else to go wrong, and in the world of RC you don't anymore headaches.

Ge|atinousFury

Got it, that makes a lot more sense now. So how do actually switch between channels? By installing different crystals?

CHassan

My Feedback: (13)

yup, change the crystals. Or if you have the dough you can get radios and recievers that you "dial in" the frequency.

HabeebThe711Guy

ahhhhhh its all falling together now how much are crystals can you keep changing them if you want to cange channels how often do they break or whatever

HabeebThe711Guy

wait i went to the channel chart and so does 75 mhz have more channels than 27 or whatever mhz is it a beter to buy the 75 over the 27 mhz. are those all the channels you can choose from

CHassan

My Feedback: (13)

For ground RC 27 and 75 are your limits (if you want to stay legal.) I wouldn't recomend going into the air frequency, just for safety issues.
If you do for changing crystals hee, you will find it is aparently illegal to change crystals by yourself. With that said, go to the track and I bet you find guys with half dozen or so crystall sets, so they can always get on a free channel.

Crystals can cost about 15 to 30 dollars. depending on where you get them and the radio you get them for. Make sure you get crystals that will work with your radio and reciever. For example, if you have a JR radio on the am band, don't buy Futaba fm crystals.

If you take decent care of them, and store them in something to keep them from bouncing around and such, they should last a good while.

RandoMere

My Feedback: (1)

well, actually there arent only 2 frequencies, as you say/think. There are: 26,27,35,40,41,72,75 mhz... In us, I think 75, and 27 are legal for cars and 72 for planes (right?). 27 is free frequency all around the world, so that means your garage door, taxi drivers or whoever else can use this frequency, that's why I'd suggest you to get 75 in US. If a crystal falls down from 30 cm height you could might aswell throw it away, that's why you should buy/make yourself a cristal case.

CHassan: "If you do for changing crystals hee, you will find it is aparently illegal to change crystals by yourself." what do you mean by that? Sorry, but my english isnt that good . Did you mean that changing cristals illegal? If that's right than I dont see why

Basicly Futaba AM cristals should work on JR AM radios. Just make sure it's AM or FM.

Maby someone should make a article about radios, explaining how each modulation (AM-FM-PCM) works and what to choose.

Hope the text that I wrote made any sence.

HabeebThe711Guy

so when i get my controller its best to get a 75 mhz because its for cars only and does the controller usually come with a crystal or do i have to buy one seperately, can you choose which channel you want for your crystal if you buy it, how big are they

RandoMere

My Feedback: (1)

yes, they come with cristals, yes, get the 75 mhz, and yes, some companies (like towerhobbies) lets you choose frequency. they are quite small, i'd say 1x0.5x0.3 cm

CHassan

My Feedback: (13)

" Did you mean that changing cristals illegal?"

Aparently in the US it is illegal to change a crystal IN THE TRANSMITTER, unless you are certified. At least that is what I have derived from some posts on here.
Here is what Futaba's site says about it.
Changing the crystal on your transmitter is illegal unless you have the proper license. The FCC has established guidelines for the modeler's safety and for the safety of spectators. For safety and FCC reasons we must request that both TX and RX be sent to the service center to ensure proper crystal change and retuning to the new frequency. Crystal based radios cannot be converted to another band without parts replacement, and may not be able to be converted at all. Certain radios can be converted, for example, from 72 to 75MHz. Please contact the service center for any other conversions.

The applicable Federal Regulation is as follows:

TITLE 47--TELECOMMUNICATION COMMISSION (CONTINUED)
PART 95--PERSONAL RADIO SERVICES

Subpart E--Technical Regulations
Sec. 95.645 Control accessibility.
(a) No control, switch or other type of adjustment which, when
manipulated, can result in a violation of the rules shall be accessible
from the transmitter operating panel or from exterior of the transmitter
enclosure.
(b) An R/C transmitter which incorporates plug-in frequency
determining modules which are changed by the user must be certificated
with the modules. Each module must contain all of the frequency
determining circuitry including the oscillator. Plug-in crystals are not
considered modules and must not be accessible to the user.



With that being the rules, I wonder why the crystals are accessible to the user??????


In the US the AMA has approved frequencies for the use with models (see ACADEMY OF MODEL AERONAUTICS APPROVED FREQUENCY USE PLAN )
The most common being 72 and 75.

HabeebThe711Guy

well has anyone here "accidently" changed there crystal was this accident hard or easy. what sites can you buy crystals from? will hobby shops sell them to you if you dont have your license?

CHassan

My Feedback: (13)

From what I understand, you pull one out and push another in. Easy as 1,2,3.

jeduardoss

That apply's for changing frecuncy from 72 to 75, or 75 to 72, or 75 to 27 without buying the hole thing, wich is the receiver and controller so that's why they sell the crystals, you can change channels if you only use the band you're receiver and controller is...I use AM 75, and has work great for me because it has a lot of channels to use, and 27 only has 6 channels so, don't buy that one...it's really easy to find someone with that same frequency...

And to change crystals its really easy its as Chassan explaind just pull out the crystal and put the new one in...

badboy2

My Feedback: (13)

the crystal is the one thats number on it and it comes with different color codes ...gelatin if you really want the bet go buy the JR XS3 it comes crystal free meaning no crystals just set the channel u want and youre set..set it and 4get it! but its a little more but no more xtals ..i think they go around 220s