RockEnRoller6

Hey I just bought a used Futaba flight pack off of ebay and I am wanting to put it into my trainer, only problem is I cant get my Tx which is a Hitec laser 4 to send a signal to the new Rx. Now I dont believe there is anything wrong with the Rx because I took it to my uncles house and his futaba Rx did the same thing when we hooked his Rx through my Tx, NO SIGNAL NO POWER!!! Okay now my hitec works just fine with my feather Rx I use for my slow flyers, so why not my futaba set-up? Could it be that I need futaba crystals? I have another question as well, I charged my JR quattro Tx over night and I wake up to turn it on and well it wouldnt turn on! So then I took the battery out and tried it in my hitec worked just fine! UGH! What the heck is going on here! Any help would be great thanks!

aerowoof

reciever cystals are manufacturer intolerant.In other words futaba recievers require futaba cystals and jr require jr etc.as far as charging the tx did you use the jr charger or the hitec?jr tx are wired reverse of evreyone else if you used the wrong battery good chance of damaging the tx as jr has no diodes to prevent that like futaba does.

RockEnRoller6

So can I just get two Futaba crystals and will that work with my Rx and Tx? Well as far as my Jr, I used a tower hobbies charger, like I said I plugged the battery into my hitec and it worked, but it wouldnt power my quattro.

aerowoof

all you need is a futaba crystal on the same channel as the tx,do not change the tx cystal it requires a hitec.jr charging jacks are wired reverse of all other meaning that most chargers and transmiters the outside contact is negative and the inside is positive.jr has the inside negative and the outside positive.I believe by using the tower charger you fried the jr circuitry.

RockEnRoller6

Okay I dont have a Tx crystal so can I use a futaba one?

rgoldy

I am not in any hurry to sign up for the crystal theory as I have flow Futaba Rx with my Hitec Eclipse Tx before-assuming you are talking FM to FM (which I think all Laser Tx's are FM). If the Rx is PCM-different story as Hitec has "QPCM" which is only compatible with other Hitec's. I think you should check polarity on your/switch/Rx along with the switch itself. Pull up the wire specs for Futaba (sorry-haven't used their stuff for a long time) and make sure it is correct and also try direct wiring the battery to the Rx to check for a bad switch.

rgoldy

Forgot about this-
You might be in that positive shift/negative shift thing that I am pretty sure Futaba's and Hitec's are different. In my Eclpse, you could set that to one or the other, I don't know about your Laser-check your manual and try that.

aerowoof

it is illegal in the us to change tx cystals,you need to replace it with the same channel hitec crystal that it originally had.hitec and futaba and tower use the same shift.jr,airtronics and kraft use the same shift.do a search on changing tx crystals and you will get the fcc regulations concerning the matter.

rgoldy

4th cup of coffee is finally kicking in. I see where aerowolf is coming from and he is right that you cannot put a hitec crystal in a futaba Rx. Too many years flying the Eclipse with a Spektrum module (which to me is one of the most under-rated Tx's out there).

RockEnRoller6

Yeah I know that but if I get another hitec crystal for my laser which is 72mhz FM and a futaba crystal for my Rx which is also FM I should be good to go then right?

aerowoof

yes as long as they are on the same channel.

rgoldy

Just get a futaba crystal for your futaba Rx that is the same channel as your existing Tx. You don't need to change your Tx.

Jazzy

OMG! I am glad I stuck with one radio manufacturer!

What brand is the RX you are trying to use?
Have you checked for correct polarity when hooking up batteries and components?

RockEnRoller6

I just need a hitec crystal for my Tx, I dont have one its gone, so I need a Tx crystal, and then I need a futaba crystal for my futabe Rx which is a FP-R127DF. Then everything should work I would think right?

aerowoof

yes

rgoldy

Explain to me why he needs a crystal for his Tx when it works with his other plane? "It's gone"-is it one of those frequency modules? If it is and it is gone (not sure how you are flying your other plane then), go ebay-ing and get yourself an Eclipse model preferable with a specktrum frequency module-that way you don't have to worry about channels as you will be able to change them.

rgoldy

Sorry-I mean "Spektra" module-there's one on ebay right now at $102 and runs out in 8 hours. go go go......

dumbthumbs999

My Feedback: (15)

Not sure about the jr quattro, but all other jr tx have a fuse which usually goes when someone charges them wrong check this first.

RockEnRoller6

Thanks aerowoof! Thats all I needed!

RockEnRoller6

I find this crystal thing quite crazy so could someone explain why exactly they only work with certain products, I mean when it comes to radio frequencies I thought all 72mhz crystals as long as they are the same frequencies as your Tx would work with all Rx and Tx. I have been researching for answers but I am unable to find any. I was under the impression that all crystals would work as long as they are the same channel not manufacturer.

aerowoof

it is not so simple crystals occilate at different frequencies or specifications,there are for a lack of a better word tuning coils in both reciever and transmitter that operate at a frequency set by the design of the equipment.a compatable cystal is needed to tune to the correct channel.say brand x tx is set at 30 mhz to operate on 72.55 a crystal is needed to make up the 42.55 difference.and if brand y is set at 40 mhz the 72.55 cystal needs to make up 32.55.this is a very rough explanation but different manufacturer cystals on the same channel have a different core frequency.it is usually stamped into the metal can somewhere,usually on the channel label.

Dr1Driver

Simply said, you need a Futaba crystal for your RX and a Hitec crystal for your TX. They must be on the same channel. As had been said, you cannot legally change the frequency of your TX yourself, so buy a matching crystal for your RX.

Hopefully, your JR has an internal diode or fuse to prevent charging the battery backwards, which will ruin it. JR TXs have a reversed charge jack. That is, everyone else in the world uses the center pin as +, but JR just has to be different and use the center pin as -. I've made adaptors to reverse the charge leads so I can use my standard wall wart chargers with JR equipment.

Check the JR battery pack with a voltmeter to determine if it's been damaged.

Dr.1

RockEnRoller6

Sounds good thank you all for your help!