How would i replace the crystal on a JR XP 8103? on most of them you can just yank them off the back.

Are you talking about changing the crystal in the transmitter? I'm not 100% familiar with this exact radio. If it does indeed have a crystal in it and not a frequency synthesizer then it is not legal for you to change the crystal in the transmitter. In order to change the crystal the transmitter must be send into a authorized dealer to make that change. I realize that most people are capable of making this change, but this is an FCC regulation.


Ken

So when i was racing cars and somtimes we had to change the crystals in there TX and RX we were breaking an FCC regulation? So if i had a synthesizer the channel could be changed with out authorization or a crystal?

I just bought a JR XP6102 and after reading through the instructions. It did say what Ken said. it also said that for shipping and regulations my crystal is glue in. so I don't think I would try that.

Chris

I don't know about the frequencies used for cars, but I do know that it's illegal to change the transmitter crystal yourself in the 75 Mhz radios used in planes. And yes, if your radio had a frequency synthesizer, or a frequency module, you can change the channel yourself. Some radios will have a module that you can slide out and insert a new module to change the channel. With those you can change the channel yourself.

Ken

I'm a Futaba guy myself so I may be wrong... I'm almost positive the 8103 use a module, you should be able to buy a new module on what ever frequency you like. As said above, you cannot just change TX X'tal's in an Air TX like you can with a ground TX... I have no idea why the FCC see ground and air differently.

John

Ok that answers that. One more question...there is no problem with changing my RX crystals to match my transmitter right. Im just wanting to make sure and do the right thing.

No problem changing RX crystal's, Just make sure you buy crystal's that match your receiver brand... Hitec for instance makes receivers that work on JR positive shift... using an RX crystal other than Hitec could cause problems.

John

As I said in my first post, I wasn't sure if it had a module or not. If it has a module it's ok to change those. You just can't change the crystals. Yes, you can change your receiver to match the transmitter

Ken

I would imagine that more regulations are put on our TX's than on ground TX's because of the relative strength of our Tx's vs most ground Tx's, and also the fact that MAYBE there are more sensitive reserves on the frequencies surrounding ours...

Gentlemen, look at the scene, cars work in 2 dimensions, and on the ground, aircraft are 3 dimensional, and at various altitudes. Look at some past accidents, a person has been decapitated by a model a long way from the field , also a model has crashed through the windscreen of a car on the highway 10 mile from the field. If your radio is not tuned to the crystal, then it becomes very easy to get out of range, a fly-away. Modules are already pretuned electronic devices in their own right , so you can change them , but you cant tell , without the necessay testing equipment , if your new crystal is in tune with the rest of the radio. That is why FCC request that a tech do the change for you , as he will test and adjust as necessary if need be, so don't gamble it will be OK, it may not be your life you are gambling with .
the_madgenius down-under Australia

Thanks for the advice. I now have 3 planes and would like to use one transmitter for all. I will get JR crystals for my Jr RX 700s to match my transmitter. That also explains why crystals are easier to get for receivers.

BTW, you can also get a synthesizer module for your transmitter. Instead of it being set for one frequency, it's got dial settings. You simply dial which channel you want to use. I've got a couple of different airplanes with different RX frequencies, so I just got an 8103 so I can quit worrying about frequencies.

The 8103 has a Module thats screwed on the back. You can purchase a new module if you so desire. IMO--not really any reason to--unless it's broke.

You buy a radio and then you buy reciever (RX) crystals to match the frequency of the TX.

Thats how it's done.

I got 2 radios. A JR652 which uses a crystal on ch 31. And an 8103 which uses a Module on ch 39.

I got 14 airplanes.

I buy Hitec RXs with positive shift for JR radios. Therefore, I buy lots of Hitec RX crystals on ch 31 and ch 39 to match my TXs.

You can yank and swap crystals in your RX anytime ya want. Tape them in with electrical tape.

Is this synthesizer something that comes with the radio or is it an extra purchase? I just checked Horizon's website to see what this module costs and cannot seem to locate ... usually attributed to user error Where can I see some specs on this in order to educate myself?

I'll be in the market for a new radio by end of summer and an very interested in the ability to change frequencies.

Thanks!

MA