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isnt a crystal a crystal?

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Old 08-06-2005, 06:28 PM
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iflyatcae
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Default isnt a crystal a crystal?

Im very confused. I thought all crystals, on the same frequency, were the same. but now Im hearing that a rx and tx have different ones? I just bought a new tx on a diff channel than all my other planes, and now i have to send it away to get it changed? why cant i just change the crystal in the tx with one of my extra rx ones? How much does it cost do have it fixed to another channel? what, technically, do they do to it?

Thanks,
ryan
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Old 08-06-2005, 06:33 PM
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exeter_acres
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Default RE: isnt a crystal a crystal?

the radio needs to be retuned to the correct frequency to prevent frequency bleed over, etc. etc.

and it is against FCC laws in the U.S. to change the frequency in your Tx.....
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Old 08-06-2005, 06:56 PM
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Default RE: isnt a crystal a crystal?

Ryan

The frequency that is printed on the crystal tab is NOT the frequency that your equipment is working on. There are typically at least 2 and sometimes 3 crystals in receivers. The one that is removeable only compleats the circuit to work on the tuned frequency. Always use the correct crystal and don't mix brands.

FYI - Changing transmitter crystals is illegal. FCC rules. It is always best to have your equipment done by qualified people. I know that often it seems to be OK to just change crystals, but you do risk losing your aircraft.

Safe Flying!
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Old 08-06-2005, 06:56 PM
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Default RE: isnt a crystal a crystal?

You could buy matching receiver crystals for whatever planes you wish to fly with the new transmitter, but having the new Tx changed should only be $20-$30. Electronic technology dictates that receivers will only operate with receiver crystals and like wise transmitters. The Federal gov't mandates that only a licensed technician may change Tx frequencies because lots of little parts must be changed/retuned to prevent the Tx from sending signals outside the bounds of that particular freq. Of course, the exception is transmitters in which the entire rf module is designed to be switched for one on a different frequency. If you own one of those transmitters, you only have to spring for $50-$60 for another module, but no retuning is required. Now that we have settled that, there is the matter of, for the most part, of not being able to use transmitters and receivers of just any different brands together; that is more than enough grist for another thread....Jim
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Old 08-06-2005, 10:47 PM
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Default RE: isnt a crystal a crystal?

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Old 08-06-2005, 11:38 PM
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iflyatcae
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Default RE: isnt a crystal a crystal?

oh, ok. I just didnt want to have to buy a whole lot of more xtals. anybody have any 45's they wanna trade for some 52's (rx of course) ? o yea, they're futaba if it matters. Maybe I should go into the market place and do this.

ps. whats all the fuss about programming, I just did my 6exa 30 minutes from opening the box.
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Old 08-07-2005, 05:56 AM
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Default RE: isnt a crystal a crystal?

ORIGINAL: iflyatcae

oh, ok. I just didnt want to have to buy a whole lot of more xtals. anybody have any 45's they wanna trade for some 52's (rx of course) ? o yea, they're futaba if it matters. Maybe I should go into the market place and do this.

ps. whats all the fuss about programming, I just did my 6exa 30 minutes from opening the box.
Try this http://members.aol.com/davthacker/ra...alexchange.htm He used to xchange xtals for $5 each.

Or http://www.stores.ebay.com/tomsrcsimulator click on CRYSTALS at the top of the page.
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Old 08-07-2005, 12:13 PM
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Default RE: isnt a crystal a crystal?

If it is illegal to change the xtal in the transmitter, why can you buy xtal sets from Tower Hobbies that include both receiver and transmitter crystals? There is no warning about the legality of changing the transmitter xtal on their site details. You would think they should know what you can and cannot do and would protect themselves from any legal problems when selling these items.

I am not disputing the statements above concerning the legalities involved. I am just making an observation that doesn't seem to make sense.
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Old 08-07-2005, 02:27 PM
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Default RE: isnt a crystal a crystal?

Because authorized repair stations purchase from "Great Planes" aka Tower Hobbies who can retune the transmitter legally. Also the "legality" question is only applicable in the US because of the FCC.

What you really need to ask yourself is this. "Does my airplance cost more or less to replace than the 25 dollars I'll spend getting the correct crystal installed and my system tuned correctly?"

I've also had recievers show up with problems when getting retuned that other wise would have gone undetected until they caused a crash so I find it very worthwhile.

One more point to ponder. Doing things off the cuff doesn't only risk your plane but possible injury or death to other pilots and spectators. Both Radio South http://www.radiosouthrc.com and Great Planes Hobby Services would be more than happy to service your radio equipment for a reasonable price. I'm lucky enough to have a repair center thats local.
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Old 08-07-2005, 05:45 PM
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iflyj3
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Default RE: isnt a crystal a crystal?

ORIGINAL: blikseme300

FYI - Changing transmitter crystals is illegal. FCC rules.
This statement has been made by many but is no longer true. See FCC 95.221 below.

It states "Each internal repair and each internal adjustment to an FCC certificated R/C transmitter (see R/C Rule 9) must be made in accord with the Technical Regulations (see subpart E). The internal repairs or internal adjustments should be performed by or under the immediate supervision and responsibility of a person certified as technically qualified to perform transmitter maintenance and repair duties in the private land mobile services and fixed services by an organization or committee representative of users in those services."

I have never been able to find rule 9 or subpart E. Additionally, when I took the Second Class Radiotelephone test in 1969 administered by the FCC you had to be licensed by them to work on this type of equipment. Then in 1983 Reagan watered down the requirements and I received a GROL to replace the Second Class. This is also when the FCC rules changed like above and below. I know I am qualified but you no longer have to do what I did to prove qualification. They don't say who certifies a person as technicially qualified except the last sentence of "organization or committee representative of users in those services." OK, who in the heck is that??????

I did find rule 9 and it is simply what type of equipment you can use and subpart E addresses equipment certification. Nothing in these parts address the certification of a person doing the repairs. Additionally, part 95 also states that the operator is solely responsible for proper operation.

Also look at www.fcc.gov/wtb/commoperators/Welcome.html and you will find:
You do NOT need a commercial radio operator license to operate, repair, or maintain any of the following types of stations:

Personal radio equipment used in the Citizens Band, Radio Control, and General Mobile radio services.



§ 95.221 (R/C Rule 21) How do I have
my R/C transmitter serviced?
(a) You may adjust an antenna to
your R/C transmitter and you may
make radio checks. (A radio check
means a one-way transmission for a
short time in order to test the transmitter.)
(b) You are responsible for the proper
operation of the station at all times
and are expected to provide for observations,
servicing and maintenance as
often as may be necessary to ensure
proper operation. Each internal repair
and each internal adjustment to an
FCC certificated R/C transmitter (see
R/C Rule 9) must be made in accord
with the Technical Regulations (see
subpart E). The internal repairs or internal
adjustments should be performed
by or under the immediate supervision
and responsibility of a person
certified as technically qualified to
perform transmitter maintenance and
repair duties in the private land mobile
services and fixed services by an organization
or committee representative
of users in those services.
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Old 08-07-2005, 05:46 PM
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Default RE: isnt a crystal a crystal?

ORIGINAL: barracudahockey

What you really need to ask yourself is this. "Does my airplance cost more or less to replace than the 25 dollars I'll spend getting the correct crystal installed and my system tuned correctly?"
nope, that isn't a problem. the question you REALLY want to ask is how much is the 25% extra the guy next to me flying worth, after it crashes due to my out of tune radio spattering the frequencies...
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Old 08-07-2005, 05:56 PM
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Default RE: isnt a crystal a crystal?

thanks Dan, very good info, tired of being a lawbreaker all these years, i feel free now
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Old 08-07-2005, 06:17 PM
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iflyatcae
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Default RE: isnt a crystal a crystal?

Im thinkin I'll just get a couple 52's to match the tx, maybe trade em to that site above.

thanks for the help.
ryan
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Old 08-07-2005, 08:53 PM
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Default RE: isnt a crystal a crystal?

I have never considered changing the xtal in a transmitter and don't plan to, but we don't think twice about changing the receiver xtal. Who is to say that one is any more risky than the other? I have not seen a response from Futaba or JR on this question. I wonder what the official stand on this is from the mfg.

I understand that repair stations buy from Tower but you would think that there would be a disclaimer for the general public if there was a problem replacing these parts.
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Old 08-07-2005, 09:49 PM
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Default RE: isnt a crystal a crystal?

Who is to say that one is any more risky than the other?
the designers and manufacturers...

http://www.futaba-rc.com/faq/service-faq.html#q198

Futaba in particular [claims] they tune to either the high or low portion of the band, so you can swap crystals within your respective portion.

receiving is inherently much easier, and requires a far lower parts count and less tuning. Besides, if only your receiver is off, you only affect yourself. if your tx is off, you affect other flyers and potentially PAYING customers on nearby frequencies.
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Old 08-08-2005, 06:29 AM
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Default RE: isnt a crystal a crystal?

ORIGINAL: iflyj3

ORIGINAL: blikseme300

FYI - Changing transmitter crystals is illegal. FCC rules.
This statement has been made by many but is no longer true. See FCC 95.221 below.

It states "Each internal repair and each internal adjustment to an FCC certificated R/C transmitter (see R/C Rule 9) must be made in accord with the Technical Regulations (see subpart E). The internal repairs or internal adjustments should be performed by or under the immediate supervision and responsibility of a person certified as technically qualified to perform transmitter maintenance and repair duties in the private land mobile services and fixed services by an organization or committee representative of users in those services."
Why is it that EVERY TIME this subject comes up one or two people feel they need to try to re-interpret the FCC rules to make it seem like it's ok for Joe Sixpack to change his transmitter crystals? If this rule had been changed, news would have spread pretty quickly. Here's what Futaba says in the 6EXA instruction manual: "Note: Should you ever wish to change the transmitter frequency, the transmitter must be sent to the Futaba Service Center for retuning." While it's obvious that the "Futaba Service Center" is not the only place that can perform this change, it's pretty clear that they are following the FCC regs.
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Old 08-08-2005, 06:31 AM
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Default RE: isnt a crystal a crystal?

ORIGINAL: iflyatcae

Im thinkin I'll just get a couple 52's to match the tx, maybe trade em to that site above.
Make sure you get the correct type of rx crystals, Futaba makes several (dual conversion, single conversion, short, AM, etc).
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Old 08-08-2005, 07:32 AM
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Default RE: isnt a crystal a crystal?


ORIGINAL: smokingcrater

ORIGINAL: barracudahockey

What you really need to ask yourself is this. "Does my airplance cost more or less to replace than the 25 dollars I'll spend getting the correct crystal installed and my system tuned correctly?"
nope, that isn't a problem. the question you REALLY want to ask is how much is the 25% extra the guy next to me flying worth, after it crashes due to my out of tune radio spattering the frequencies...
While that is true, most people that are going to skimp a few dollars to risk an airplane care more about their own plane and their own wallet and not the poor guy next to them that will probably never know his pride and joy got shot down hence the reference to their own equipment.
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Old 08-08-2005, 07:45 AM
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Default RE: isnt a crystal a crystal?

If the crystal is accessible from the outside of the case, I can find no FCC or AMA regulation that prevents the user from changing crystals.

And every time this subject comes up, I ask for someone to cite an applicable regulation. So far, none has been presented.

I know this is fanning the flames, but I'm tired of people who continue to say this is against FCC regulations.

Show me the law and I will gladly comply.
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Old 08-08-2005, 08:29 AM
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Default RE: isnt a crystal a crystal?

ORIGINAL: CrashGaalaas

If the crystal is accessible from the outside of the case, I can find no FCC or AMA regulation that prevents the user from changing crystals.
Every major manufacturer and most (all?) industry experts agree that the FCC regs require a qualified technician to do this work. It's interesting that you think you are better at reading and interpreting these regs than the FCC itself, the manufacturers, and industry experts. This has been hashed out over and over, and the conclusion ALWAYS supports what has been said. Unfortunately, a small number of self proclaimed regulation "experts" refuse to accept this conclusion and feel they need to insert their misguided opinion every time this comes up.
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Old 08-08-2005, 09:49 AM
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Default RE: isnt a crystal a crystal?


ORIGINAL: piper_chuck

Every major manufacturer and most (all?) industry experts agree that the FCC regs require a qualified technician to do this work. It's interesting that you think you are better at reading and interpreting these regs than the FCC itself, the manufacturers, and industry experts. This has been hashed out over and over, and the conclusion ALWAYS supports what has been said. Unfortunately, a small number of self proclaimed regulation "experts" refuse to accept this conclusion and feel they need to insert their misguided opinion every time this comes up.
Chuck I suggest you read the FCC rules your self. I put the important ones in this thread. But the following you can find for yourself which is the FCC site which you must have over looked.

Also look at www.fcc.gov/wtb/commoperators/Welcome.html and you will find:
You do NOT need a commercial radio operator license to operate, repair, or maintain any of the following types of stations:

Personal radio equipment used in the Citizens Band, Radio Control, and General Mobile radio services
.

It doesn't take a mental heavy weight to interpret this one.

When it comes to the rules I'll take the FCC ones over anyone else. Sure the service centers and manufactures want you to send it back so they can charge for the work,,, DUHHHH.

I have been licensed for 46 years to do this kind of work. The license I now have is only needed to work on avionics which is the main reason I got it in the first place. However, I have followed this closely and you know my interpretation.

I would love to have you have the FCC to prove me wrong in writting.
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Old 08-08-2005, 10:08 AM
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Default RE: isnt a crystal a crystal?

Piper Chuck,
Dave and I both have more to lose by not following FCC rules. We are both subject to losing our amateur privileges for violating any FCC regulation. Believe me, if there is a regulation against changing crystals, we both want to be aware of it and comply with it. Like I said before, no one has ever been able to show me such a regulation. Sounds as if you know what it is, please share it with us.

Larry KBØR
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Old 08-08-2005, 11:39 AM
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Default RE: isnt a crystal a crystal?

The reason rx's can be changed and not tx's is that rx's do not transmit a signal and therefor connot affect anyone else if not working properly, only the user's plane.
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Old 08-08-2005, 11:54 AM
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Default RE: isnt a crystal a crystal?

ORIGINAL: iflyj3
Chuck I suggest you read the FCC rules your self.
I have read the rules in this area very carefully. I'm not going to participate in yet another never ending dabate on what each part says or does not say. It's been done, and the conclusion is ALWAYS the same, Joe Sixpack cannot change transmitter crystals.

This discussion is about what Joe can and cannot do. It's not about what a ham operator, or someone who's licensed to repair avionics, can and cannot do. I've found nothing to support the claim that Joe Sixpack can change his own transmitter crystal. People with amateur radio licenses, avionics licenses, etc have significantly more knowledge of radio workings, and therefore have more priviledges, and responsibilities, than Joe Sixpack.
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Old 08-08-2005, 12:20 PM
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Default RE: isnt a crystal a crystal?


ORIGINAL: iflyatcae

Im very confused. I thought all crystals, on the same frequency, were the same. but now Im hearing that a rx and tx have different ones? I just bought a new tx on a diff channel than all my other planes, and now i have to send it away to get it changed? why cant i just change the crystal in the tx with one of my extra rx ones? How much does it cost do have it fixed to another channel? what, technically, do they do to it?

Thanks,
ryan
One thing should be made clear- The transmitter and receiver crystals are not interchangeable. They are not the same frequency.
Now go on and fight about the regs.
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