rccub

My Feedback: (184)

just bought a used jr quattro for my sons trainer. it came without a crystal. how do i know what channel it was on. the previous owner said i can pick any channel. is this correct. thanks
charlie

will

The best thing to do is to send it to a repair center or JR to have a crystal installed and tuned. Did you get a crystal with the receiver?

bhanley

Some guys do it (use any channel...) but its not a good idea. If you have a need to change
channels, you, in general, should not move more than 2-3 channels either side of the channel the transmitter is tuned
for. Since you don't know what channel that is you will have to send it in to Horizon for a check. At that
time they can tune it for any channel you wish.

JohnBuckner

My Feedback: (1)

No this entirely incorrect and this person did you a disservice by proviously playing musical chairs with the Tx crystals. In reality here in the US it is in fact aginst FCC regulations to change a Tx crystal without retuning. Yes you can change Rx crystals at will but not Tx. The exception to this are module type tx where the entire RF section is in that module and no tuning is neccessary because the entire module is changed out. Your Tx is not a module type. Another exception is a synth type modules or Tx.

As the others have said if all the channel stickers have been removed by the former owner then you have not option but to return for a channel # of your choice with a retune.


checking occasionally at our public field with a scanner we are discovering more and more folks that have been flying on a channel entirely different than what they have beleved. This is the down side to a booming Ebay.

John

Scar

My Feedback: (3)

Just out of curiosity... does this radio have an antenna? Last time I saw a post like this, it turned out the "transmitter" was actually a buddy box.

Good luck,
Dave Olson

rccub

My Feedback: (184)

it does have an antenne. i recently asked a "jr" man, who is supposed to be well versed in radios, and is in fact sponsored by jr, the same question. here is his answer. " jr center tunes their radios, so you can pick any channel you want.

JohnBuckner

My Feedback: (1)

More disservice and inaccruate information. That statment applies To Rx's and Rx's only and in that regard he is correct. However this does not apply to your situation. Its a fact in the US it is aginst federal regulations to be randomly swapping Tx crystals in a non module type or synthsized Tx. Even if your swap works to your satisfaction The real danger is our free and unlisenced use of the band. There are 'Primary users' interspersed between most of the 72 Mhz band hobby channels. We are classified as 'Secondary Users'. If we interfere with these Primary users then we as secondary users must cease and desist. These industrial channels are located All over the US and there is no 'middle of no where' in regards the RF spectrum.


This is precisely the reason New folks should avoid places like E bay untill they know more about what they are buying. Used radios often turn out to very expensive units. I can only urge you to do the right thing and send it in for a retune to the channel of your choice.

John

rccub

My Feedback: (184)

i am going to send the transmitter to horizon. i am not going to risk it. for what its worth, the guy i bought this from, is a regular user of the for sale forum right here at rcu. thanks for everyones input.
charlie

laryboy

My Feedback: (2)

checking occasionally at our public field with a scanner we are discovering more and more folks that have been flying on a channel entirely different than what they have beleved. This is the down side to a booming Ebay.

now john ! think this one over.

JohnBuckner

My Feedback: (1)

Nothing to think over. There have been a number of incidents locally and all have been the result of used radios purchased where the buyer was told that the Tx/Rx combo was such and such channel. In every case the channel stickers had been removed and the original owners had been swapping crystals (Tx/Rx). The purchasers have all been new folks without any idea how to identify a crystals real channel number by its imprinted freq. and only going by just whatever channel number they had been told by the seller. Therefore all have been merrily flying away on a channel that they were not clipped up for! Simple.


Being aware of this happing more and more just from talking to people I decided in my own defense to purchase a scanner and on its very first outing to the field most definately saved my most treasured competition airplane. Practicing alone a visiting flyer showed up (we are a public use facility). I had just landed and thought to get in another flight as the visitor got ready and I was on #18. The visitor pinned up on #17 and we both verbally confirmed what channels we both were on. On a hunch I decided to wait instead and just check when he was down the line and turned on, sure enough he was on #18 not #17. Discussing this with him it was a used radio and he had been flying it at his home field for a year pinned up on the wrong channel. We removed his crystal to confirm and checking the channel chart confirmed he was on #18.

Since then three more local flyers have been isolated all with EBay radios that were most definately not on the channel that they thought and all were non module, none synth Tx's.

Nothing to think Over

John

Nubie_1

Now I was told by someone who should be in the know that JR crystals could be changed as long as the one in the radio and the one in the receiver matched to alleviate to many people being on the same channels but Futaba had a certain range they had to stay within on the original crystal numbers like a high end and low end frequency. Id like to hear that from a JR tech or someone with credentials nothing personal to anyone in here Ive learned a great deal of info even with a grain of salt from these forums and everyone who contributes.

Thank You
Chris

laryboy

My Feedback: (2)

its a great story

JohnBuckner

My Feedback: (1)

Hi Chris

If you want only a responce from the manufacturer then you should ask at the Manufacturers direct support forum Here:


http://www.rcuniverse.com/forum/forumid_116/tt.htm


Here in the open forum by nature every reply will of course be opinion by every responder.

John

ZAGNUT

My Feedback: (1)

just because it's against FCC regulations to swap crystals doesn't mean that JR radios aren't center tuned to use any 72mhz crystal. it's not that hard to accomplish and most likely the distributor just grabs a crystal and plugs it in depending on what the customer ordered.

i know for a fact that the 72 mhz FMA RF modules i use are tuned only for hi/low band and NOT FOR ANY SPECIFIC CHANNEL. module with "A" on it covers 11-33 and "B" covers 34-60. the crystal for the channel you want comes in a separate package.

i have also seen radios sent in for a "factory authorized crystal change and retune" come back with absolutely no evidence that any of the RF coils were touched.

and there are plenty of other countries out there that also have industrial equipment on 72mhz and could care less about crystal swapping hobbyists


dave

laryboy

My Feedback: (2)

we dont care what you do in ISRAEL. in the U.S. we should follow regulations even tho they are a pain

ZAGNUT

My Feedback: (1)

not saying you should break the rules just sick and tired of all the disinformation about crystal swapping and how "dangerous" it is. i wish more manufacturers would specify how their radios work with regards to changing channels instead of the standard "send it in for service" crap.

if i ever come back to the states i will for sure use the ham bands where i'm allowed to make responsible decisions about my radio gear and it's tuning without fear of breaking some lame rule


dave

ZAGNUT

My Feedback: (1)

and lets face it, since there is usually nothing on the radio itself for identifying the channel how are you going to catch somebody that does it? a rule without any means of enforcing it is pretty useless. so again, give the users the information about how to swap channels safely and let them be responsible.



dave

F106A

My Feedback: (2)

Hi everyone,
There's a simple way to check the channel you're on if you know the frequency:

Look at the crystal to get the frequency, say it's 72.090. Take the first two numbers after the decimal point, in this case 09, add 21 and divide the result by 2, and you get the channel.
In this example, it's 09 + 21= 30 divide by 2 (30/2)=15, so this radio is on channel 15.
It's simple enough you can do it at the field to check any suspect Tx.
John is correct, the FCC doesn't care about receivers, their regulations control transmitters and if you modify an existing Tx without the proper license, you are in violation of the law, and the AMA safety code.
BRG,
Jon

rccub

My Feedback: (184)

thats a good formula, but how do you check when there was no crystal in the radio when i got it.

JohnBuckner

My Feedback: (1)

OK lets lets talk about "responsibility" My idea of being responsible is not ignoring a law simply based on its probability of enforcement. My idea of responsibility is if you are "tired" of a law then you should work to change that law. If you happen to be a US citizen then great on your return to the country start to work in changing it. If you are not a US citizen, fine then imigrate to the country, become a citizen and then please make the effort to change any law that displeases you. I am not interested in the applicable laws of the land where you reside or the applicable laws of the Uk. I am interested in the applicable laws of the US which is where the original poster resides.


!. The original poster was taken advantage of by either an unscrouplous or ignorant seller stating that is OK to use any channel he pleases (including the tx) Wrong it is aginst US Regulation.


2. Apparently the original poster was told by a person who receives free radios (in most cases) because he wins contests with a manufactuerers shirt, hat and decals stuck on, that (or at least the implication was made) it is all right to change Tx crystal based on the way JR tunes their Tx's. Perhaps there was miscomunication between the two, but regardless Wrong it is aginst US regulation.


3. Original poster decided to do the right thing and retune for the channel of his choice. Thank your rccub and welcome to the Passion. That Dave is showing " Responsibility."



John

F106A

My Feedback: (2)

Hi,
Why would anyone buy a transmitter with no crystal in it? You couldn't check to see if the Tx is any good.
Makes no sense to me.
BRG,
Jon

ZAGNUT

My Feedback: (1)

John,

simple fact is that tons of US modelers will continue to swap crystals despite it being against the law. so wouldn't it be just a bit better if these lawless modelers could at least know how to safely swap their crystals?? all it would take is a few extra lines of text in the manual similar to what FMA did.

as for changing the law, no thank you. how about i just interpret it in my own way?? seems to be how everybody else does it... putting a drop of glue (that doesn't even stick) on a very accessible crystal does not magically make it inaccessible and in compliance with the rules. maybe the manufacturers/distributors are the big law breakers here??

yes, rccub did the right thing and sent the radio in for "service" but i'm betting it isn't even opened up. they'll just grab a crystal off the shelf, plug it in and send it on it's way.

and yes, i am a US citizen and like i stated before i will simply use the ham bands if i ever return. either that or make sure nobody sees me swapping crystals in my homebuilt radio disguised as an old ace or proline....



dave

Nubie_1

I find it odd that if this is such an important law not to do this that I can go to any on-line hobby store and buy a tx rx crystals sets on different channels or my local hobby store in town,If this is such an important law then there shouldn't be anyway to circumvent the channel in radios without sending in the radio to a certified shop for work.

Chris

JohnBuckner

My Feedback: (1)

First a rationalization based upon your perception that everyone ignores laws to suit themselves. Then a flat refusal to work within the system to effect change which you perceve neccessary. Lastly a detailed account of how you plan to "disguise" your disregard of the law from your fellow citizens and modelers.

I would hazard a guess that "tons" of your fellow citizens and modelers would definately consider this a reprehensible attitude.


I beleve the thread starters question has been adaquately answered even supported by you Dave and using this thread for an off topic vendetta aginst US law is just a little off color. Perhaps a better place for your anger would be in the AMA forum. I will let it lay now, have no interest in further political argument and have already stated my feelings.

John

ZAGNUT

My Feedback: (1)

how convenient it is to be able to quote a post but delete the parts you don't feel like challenging:

"as for changing the law, no thank you. how about i just interpret it in my own way?? seems to be how everybody else does it... putting a drop of glue (that doesn't even stick) on a very accessible crystal does not magically make it inaccessible and in compliance with the rules. maybe the manufacturers/distributors are the big law breakers here?? "

add to the above that crystals are available over the shelf to all us no good lowlifes so i stand by my interpretation of the law: crystal swapping is fine and should it cause any interference then the manufacturers should be held accountable for not providing the proper guidelines for end users. just wait until one of these ebay buying, crystal swapping criminals with a park-flyer shoots down a $10,000 jet and see which way it goes in court.

and the last sentence in my previous post was an attempt at humor


dave