Missileman

I have been told by people here on RCU that changing the channel on your transmitter by simply changing crystals is illegal.
I have been told by 3 different hobby shops as well as numerous people in my club that it is not.
What is the truth and what FCC regulation states this?
Note: this started when I was in search for a crystal for a reciever I had and couldn't find one localy on my channel, the hobby shop owner offered to sell me a set on a different channel and said I could change both (I didn't buy the set but I did ask around)

bruce88123

He lied to you, although it may have been unintentional. Look at the references Ken just posted in the previous thread you were on.

You should tell the LHS's that they are advising people to violate Federal Regulations.

Campgems

Any chance you could give us a link to Ken's post. I have no clue as to where to look, and I am interested in this topic.

Thank you

Don

Missileman

I started here but deleted my post, didn't want to hijack
http://www.rcuniverse.com/forum/m_4799720/tm.htm

bruce88123

I wouldn't have considered it a hijack as it was a closely related question but thanks for caring.

Campy

My Feedback: (1)

FCC rules state that unless you are a certified technician (I am not sure what area ) it is illeagle to change the crystal in the transmitter.

That being said, a lot of people do do change the transmitter crystals illeagly. I don't know what the fine is if you are caught, but I imagine it is not cheap.

That is why I like my Tracker radio - fully synthysized. I just pick the channel I want (on 72 mhz) and I am all set.

RCKen

My Feedback: (9)

Here's the same thing I posted in the other thread.

If you are interested in the full text of the regulations concerning this matter they can be found at:

[link=http://www.access.gpo.gov/nara/cfr/waisidx_04/47cfr95_04.html]FCC Title 47, Part 95 - Personal Radio Services[/link]

Copied from Futaba's website

Copied from FCC regulations concerning this issue

horace315

My Feedback: (15)

my question is this,when you order a radio from lets say tower?they ask you what channel,all they do is plug in a crystal and put a freq,sticker on the radio.that being said,who would know if you changed your transmitter freq?this is just a hypothetical question.its my understanding that these radios are either low band high band,and depending where you purchased it from,mode 1 or2.is there any internal number specifying it to be on the channel it was sent with?i might be wrong but will any high band crystal fit a radio that has that designation.and if you buy a second hand radio and the crystal was changed is it illegal to buy it?

skiman762

(b) An R/C transmitter which incorporates plug-in frequency
determining modules which are changed by the user must be certificated
with the modules. Each module must contain all of the frequency
determining circuitry including the oscillator. Plug-in crystals are not
considered modules and must not be accessible to the user.


Does this mean JR tx are in violation of federal law since the crystal is right there on the back accessible to the user?
where are Futaba crystals located ?

BarracudaHockey

My Feedback: (11)

Transmitters have a sticker on them and often the crystal cover has a tag denoting the frequency, I believe the big shops stock well enough to serve requests. Actually as I remember, the sealed box has a sticker with the channel number.

In any case its illegal to swap crystals in a transmitter or the crystal in a transmitter module, it violates type acceptance. You or whomever changes it needs to proper equipment and technical know how to ensure that the transmitter is within specs. There are three reasons, 1 if its off freqency you could interfere with other models. 2, we are freeloaders in the band, there is big paying commercial users between our channels, cause interference with them and you will find out what the fcc can/will do and 3, if there were a serious accident and post crash analysis indicated an illegal freq change you could be paying the freight yourself.

Synth units, and units that you change the freqency by changing the whole RF module are legal to change.

bruce88123

Tower has a large number of radios in stock and they tell you in their ads which channels they have available at the time of order. I'm sure they also have access to a shop where they can have them changed if absolutely needed. They are not going to break the law and change crystals and ship to you. Ask BAX if you doubt this. He is the Futaba rep on the Futaba support forum. "all they do is plug in a crystal and put a freq,sticker on the radio" That's plain ludicrous, sorry. Your LHS may pull that crap. [:'(]

WCB

The FBI has a special branch with the sole mission of identifying criminals who have changed their transmitter crystal. They hit your shop in the middle of the night with a SWAT team and seize the offending transmitter. Then they haul you off to an undisclosed location and interrogate you for hours and show you satellite images (obtained from the CIA) of you actually operating the illegal device in order to coerce a confession. You're toast! Better hope they didn't find those pillows you tore the tag off in violation of Federal law! That's another whole can of worms.

RCKen

My Feedback: (9)

While all of this may sound very silly, there are very good reasons why this is regulated here in the US. To put it at it's base level, airwaves are at a premium in this country. The bandwidth that we use is regulated and restricted for our use, and our use only. This of course is a good thing because we don't want our expensive planes crashing because somebody used a garage door opener. Right??? Well, the FCC does this same thing for other frequencies too. In fact, within the bandwidth we use are other frequencies that are used by other things in this country. For instance, anybody that has every flown in a town that has a television station on channel 4 knows that the RC channel 20 is usually not usable. This is because of bleed over (not always, but sometimes) from the television station. When the crystal in a radio is changed the repair facility has to ensure the the radio is indeed broadcasting on the proper frequency and within set power output standards. If they are not the repair facility makes the adjustments. Now, what happens when somebody decides to change their own frequencies?? Worst case scenario here, but still very very plausible. Let's so "Joe Nobody" changes his transmitter from channel 60 to channel 20, and the output power is off and he is now interfering with "W-something or another" channel 4 television station's broadcast. They call the FCC to report the interference. FCC comes out with a spectrum analyser and scans for the interference. They find "Joe Nobody" flying his $100 ARF at the local field. FCC shuts down the field for starters, and to ensure that this doesn't happen any longer they revoke the frequencies we use and sell them to somebody else.

Ok, sound silly? Maybe a little far fetched, but still possible. There are a lot of people that would love to get the frequencies that we use for our RC planes. The FCC has set those aside for us to use, but they put these rules on their use in ensure that we don't interfere with people using other close frequencies for commercial use. I for one appreciate the fact that we have these frequencies set aside for us and I'm more than happy to follow these rules for their use.

Hope this helps clear it up.

Ken

raideron

My Feedback: (1)

Are we getting a bit off base on this subject... The law states as Ken has it listed..
I am most likely wrong... But I did not think installing/removing the correct ordered
set for the radio would be a problem... For me IMO it's to not deviate from the said set
that your ordered that had been tuned and checked from the manf...

It's true you would most likely never get caught.... But there are safety issues.... And
low and behold, don't get what ever agency P.O'd at you and have them find out that
you did it, You'd most likely find out what that statement/penalty meant then

hogflyer

On the flip side, those rules also protect us making sure other's don't cause interference on our frequencies, ensuring we can safely operate our aircraft with out fear of crashing or worse....

Hogflyer

horace315

My Feedback: (15)

Ken i understand rules,we all have to abide by them,i guess some things are so simple we take them for granted.
and Brucie i asked a question not made a statement.I'm sure they use robots or might even plug them in by hand on an assembly line,i was curious if they actually had that many in stock,or did they do their own?

skiman762

Now that all the legal stuff is out on the open
anyone want to guess how many TX have had the crystals changed ?
I'll guess 50% or better

exeter_acres

My Feedback: (2)

Bingo!

A recent death of two people at an RC airshow in Europe was beleived to be caused by an area transmitter tower that just happened to be on the similar/same frequency as a giant scale airplane

Cyclic Hardover

My Feedback: (3)

You know, this isn't going to come out right but it's only an observation. The FCC's enforcement of its policies and regulations ranks right up their with my odds of winning the powerball lottery. I have been around aviation for over 30 years in one respect or another. As long as we have Howard Stern,The Daily Show, Cable and Dish network, changing out a tx crystal is not even last on their list but they probably wouldn't even know what the heck your talking about if you asked them!

carrellh

Futaba crystals are plugged into the front of the transmitter. There is a tiny drop of glue on one corner of the crystal cover, attaching it to the case. You have to “break” the transmitter to remove the crystal. I have to assume their legal team determined this was enough of a ‘good faith effort’ to keep them out of court if a renegade customer changes crystals and creates a problem.

Since many of their transmitters are sold all over the world, and some locations do not have channel change restrictions, they don’t want the unit destroyed when those customers break the crystal cover loose from the case.

Campgems

I'ts more than just changing the crystal. The RF final has to be tuned to that crystal. If you changed just one channel, your final would be close, but from one end of the band to the next, your output would drop considerable, and what was transmitted, would not be clean. Back in the late 60's, I built a transmitter, receiver and five servos from a Royal Clasic kit. There was a lot of fine tuning that went on. I ended up borrowing an O scope from work to get it tuned correctly. That was in the days of citizen band, 27mhz radios. I think the FCC put the kits out of business.

Don

doubledee

My Feedback: (4)

I have a $4000 dollar airplane and am flying it at your flying field. You arbitrarily change the crystal in your transmitter and because iyour transmitter hasn't been retuned to the discreet frequency it slops over onto my channel and causes my airplane to crash. I am going to be very, very, very upset and I can almost guarantee that you will be buying me a new aircraft.
DON'T CHANGE YOUR TRANSMITTER CRYSTAL WITHOUT HAVING THE TRANSMITTER RETUNED!!!!

doubledee

piper_chuck

My Feedback: (12)

That's a pretty sad commentary on your fellow modelers.[:@]

bruce88123

No two crystals, even of the same channel, are identical or on the same freq except by chance. Do you guys realize that a crystal is a "rock" that has been cut to "vibrate" at a particular frequency when stimulated? It's darn hard to cut "rocks" identically. That's why there are are circuits in the radio to make up for the differences in the "rocks". And these "rocks" can have defects which can cause problems which the shop can detect on a spectrum analyzer during setup.


And I don't care how many people have already changed their own crystals ILLEGALLY, it's still Illegal and the wrong thing to do. If you can't afford to send your radio to a shop, stop flying. That's my opinion. [:@]

AA5BY

If I recall correctly... Futaba back in the '70-'80s certified their transmitters compliant one up or one down... giving a three channel option. Changing the crytal by the owner one up or one down did not void the compliance.

But, times seemed to have changed at least with my JR. Its manual does not offer such compliance, saying that no owner frequency changes are permitted, though a Ham ticket might provide the freedom to change frequency and adjust ones own transmitter... please don't stone me if I'm wrong, I said, "might".