the chips in both the reciever and controller dont match, here is a picture, what problems will this show. incase you cant read the numbers, the top from the reciever in the plane is 72.330 and the controller is 75.430. thanks for any help

By chevyv8 at 2010-02-14

we proably need to know what radio and reciever you have

Well, the biggest problem is that they won't work together. The top crystal is channel 27 (72.330 Mhz) which is a frequency dedicated to RC aircraft. The bottom crystal is channel 62 (75.430 Mhz) which is a frequency NOT dedicated to RC aircraft. In order for your radio to to work properly both the transmitter and receiver must be on the same channel/frequency. Also note here, it is illegal in the US or anybody other than a licensed repair facility to change the crystal in the transmitter of an RC radio. It is ok for the end user to change out the receiver crystal, but not the transmitter.

Ken

So what Ken is saying is:

If you plan to use this radio for a car or boat, you'll need to replace the crystal in the receiver to channel 62 (75.430)

If you plan to use the radio for an airplane, you'll need to send the transmitter to a radio repair facility and have THEM change the crystal to channel 27 (72.330)

Thank you for the response. I guess I have to call my hobby shop than.
Why is this illegal? It looks like both chips are of the same size. It's going to suck if I have to ship this out nd pay someone to perform a simple change.

It is illegal to change the Transmitter crystal yourself because the radio needs to be tested and retuned at the same time to insure that it is at the frequency that is indicated by the crystal, and not bleeding over into other channels. I was once quoted about $50 to change a transmitter from one 72mhz channel to another, it may be higher to go from one band (75mhz) to another (72mhz) Unless you have a high-end transmitter, it may be cheaper and simpler to pickup a used 72mhz radio on the auction site. They usually go pretty cheap.

Wow! That sucks. Thanks.

MinnFlyer,

I have a few crystals that I am going to get rid of because I switched to 2.4, but I have a question. I noticed on the different crystals I have that the numbers after the 72 are different from one another. For example one will say 72.330 and one will say 72.150? Does each 72MHz channel have a slightly different number??

I have another ? regarding this. If I have another crystal from a different reciever, can I put that crystal in the controler for the plane. At least for testing purposes. I bought this plane used and would like to have a list of all needed items so I can place 1 order.

72 MHz is the "band" of frequencies used. The specific frequency, 72.330 MHz means 72,330,000 Hertz or in the old language, cycles per second. The transmitter and receiver must match for this to work.

And, to answer a previous question, these are crystals, not chips. And, they may or may not look alike, but that does not matter one bit. The outward appearance means absolutely nothing. It's what's inside of the "can" is what matters, and these "crystals" are "CUT" to a specific frequency.

The aircraft band has 50 channels, starting at 72.010 for channel 11 up to 72.990 for channel 60.

CGr.

And to answer the other question, no you cannot use a receiver crystal in a transmitter and vice versa. They are different.

CGr

Thanks again. All my equipment is futaba, can I use a crystal from hitec? Or is that a problem too.

Thanks for all the help. My hobby shop only cares about sales. They put no effort into assistance. Good to loose business

I don't know if they are compatible. Just remember that the only crystal you can swap out is the receiver crystal. You CANNOT legally swap out the transmitter crystal. That's not just one of those "tongue-in-cheek" statements, either. If you swap out the transmitter crystal and cause an accident you are liable. And, it is pretty easy to detect. The guy standing next to you with his radio on may see problems develop when you turn yours on. That's due to the bleed over or incorrectly aligned transmitter.

Get the correct crystal for your receiver. And, if you want to change transmitter channels, send it in to either Futaba or Radio South.

CGr.

Ok. I appreciate the continued help. The guy I bought this stuff from is giving me a different 7 channel controller with a crystal labeled 72.070 type 72-70 and a 7 channel reciever with a crystal labeled 72.070 type 72-10 rx14

I hate to ask, but will this work? Or do they both need to be type 72-xx

Thanks again. If this will not work than I know what I need to do. Again this is just for testing and solo low level slow speed flight use. I will not be out with anyone else.

Your making a mountain out of a mole hill trying to save a dollar......(A) Never remove the crystal (xtal) from a Transmitter (not controller) it is as the rest are saying illegal to change as you need a certified oscilloscope technician to tune the xtal,,,(B) If you have a receiver (Rx) then all you need to do it look on the back of the Tx (Radio/Transmitter) and it will tell you what channel you need from 15-41-58 whatever single number is back there,(I am on channel 41) get THAT brand of Rx and order a crystal for that number they are anywhere from $3 to $19 depending on the brand.......you do not want to mix brands unless your plane is a parkflyer...go to tower hobbies, under futaba (I assume you have an FM radio) and order the xtal for the number on your radio, sounds like your hobby shop isnt the best , but they wont carry a whole line of xtals and they'll have to order it anyway.........you dig?....while your online see what else you need to order, fuel line,extra glow plug,plug wrench, tools....all manner of things....what plane is it you have?...glow ,electric...it will make a difference in the price, you can get a Rx/Xtal for $18 for a parkflyer.....Rog
To recap, you dont send a radio off to match a rx you buy a new xtal for the rx, that simple..

I understand its "that simple" however someone well above your reply said that the crystal I had in my transmitter is not dedicated to aircraft.
Thank-you for your response though. The plane I bought is an older bi-plane with a 54" span, and 120 size 4 stroke. Everything is there to get it off the ground, I just need a few things and obviously some questions will arise. That's why I am here. If you couldn't tell electronics are not my strong point.

Ok sorry if I came down hard, and I did miss that post, but someone sold you all this together as a beginner?..I can tell you from experience, your better off getting a tx on the bay or here in classifieds than sending yours off, I sent mine off to be changed and it cost me $105 with shipping (this was tower with a quote of a $50 fee and shipping, which did not include parts and labor, so I dont know what fee means to them?).....are you a beginner?...thats an awful lot of airplane/engine for a new guy....Rog
Ok I see you are getting a 7 channel tx now too...but forget the crystal numbers what you need to know is the channel...can you get us a pic of the tx's, the first one should only be 2-3 channel if it is ground or water use....

OK Chevy,
Here's the skinny...

On your new Transmitter and Receiver, yes, both of them match, so they will talk. They are 72.070 Mhz which equate to Channel 14 on the 72 Mhz spectrum. There is a lot to know about these setups, but I think you are set.

Now, if you are just learning to fly, please don't try to fly the Biplane. Most of the time, Biplanes aren't even good second planes, or 3rd planes. I'm not going to rail on you, but start slow, or else you could do a lot of damage or injure someone with it.

With that, good luck and enjoy,
Curtis

flyinrog - no worries! thanks for the input
beau0090 99 - thanks for your response

I guess you can say I'm starting off again. I was in to this about 20 years ago. I started off with a foam single wing plane with a 15 or 18 size engine. My next plane was a balsa bi-plane with a slighlty larger motor and 1 or 2 more servo's
The reason I stopped back than is because of cash flow. I was in school and heavy in sports. After school, I concentrated my efforts and money on drag racing. I bought and built a 2001 Camaro SS. I built that beast to live on the street yet drive to the track and bust out consistant 10 second 1/4 mile time slips on straight chevy engine with no power adder. I have never lost the interest in the rc hobby, I have a couple crazy trucks, but the want to get back in the air never died. My co-worker told me about a personal sell-off of his "inventory". So I took advantage. For a very good price, I picked up this bi-plane, 2 extra props, manuals, blue-prints, charger, and all electronics PLUS a 60 series heli with extra rotor, starter, training platform, manuals, and all electronics. I have no intention of geting back in the air with either of these birds. I am looking for a cheap used bird to get off the ground, and also a simulator for the computer. My idea is to get these 2 birds ready so that when I am ready they are good to go. Here is a pic


By chevyv8, shot with DCR-SR82 at 2010-02-13

I hate to see this happen to new guys. There is no way your buddy flew these birds with that transmitter and reciever combo. If he is disohonest enough to sell you that stuff claiming that it will work, then who knows what problems lurk in that setup? I would be honestly concerned that he has changed the transmitter crystal. If the sticker and the frequency marking don't match what the crystal says, then that is definitely the case and the radio will have to be sent off to have the frequency changed and retuned. Given the selloff that is happening right now with 72mhz stuff, it's probably not worth the expense.

No, he simply mixed them when he handed me everything. I was in his shed with him and there must have been at least 6 transmiters that looked almost alike. The original transmitter had written in faded black marker on the back "white xxxx" indicating something. The transmitter he gave me last night says "purple bi" indicating the plane I bought. The reciever is exactly the same in apperence so instead of re-routing the antenna lead I just changed the crystal in the reciever. It all works now. Even from down my street with the plane in the house. I don't believe there is a problem with this. Do you still think so?

You're probably fine.
Go for it,
Curtis