iflyj3

My Feedback: (7)

Del,

What they sent you has nothing to do with your question. In the regs there is the statement that a certificate is not required to service radios in the radio control service.

Used to you had to be FCC certified to service R/C stuff, but no more. The regs say you must be qualified but do not say how to be qualified. I hold the GROL which used to qualify me but that is not needed anymore for R/C. I can still use it for avionics.

iflyj3

My Feedback: (7)

This is quoted from the November 2005 issue of the magazine R/C Report. Tony Stillman's article on page 83.

"Exactly what do service centers do during checkups? Usually it begins by testing the transmitter to be sure it's on frequency and that it's narrow band. This is done using a spectrum analyzer. If problems are found, the RF circuit is adjusted to meet current specifications. If the problem is an off-frequency issue, it may require that the crystal be replaced. This is not an unusual occurrence, although, we do see this type of problem from time to time.

Once the frequency is checked, the RF output power must be tested to insure an adequate signal is being transmitted. This can show itself in a range-check, but many times the RF output of a transmitter is not peaked from the factory. This is due to the way that the radios are manufactured now. The units are tuned using a factory standard crystal after which they replace the crystal with whatever frequency they're building that day. Tuning the system in this manner results in plenty of power in most cases, but the individual transmitter is not tuned with the crystal that's in it when we buy it. When this radio reaches a service center, we very often find that we can improve the output power by 10-25%. This is quite a difference. but not generally enough to cause a crash. Still, it's nice to know that your radio has been tuned for its full power output."


The color emphasis was added by me. Make up your own mind as to changing crystals.

s3nfo

My Feedback: (14)

It is legal to change receiver freqs, so why don't you just change the ch 25 Rx to ch 20 and be done with it.......

Charley

My Feedback: (2)

There is no FCC reg that says you may not change the transmitter crystal. Some people take that FCC writing about the freq determining components not being readily accessable to the user and reinterpret it mean, "thou shalt not......", when all it means is that you have to open the box to get at stuff.

I have an Airtronics Vangaurd transmitter that I bought on chan 22. I bought a chan 21 trans crystal and have been flying with that transmitter for years on 21, no probs and no interference caused to those around me. Not sure I'd try it for a 5 channel change tho. That's probably far enough off that the transmitter ought to be retuned. I'd be alittle worried about it splattering enough to cause adjacent channel interference. I'd send it in to the mfr. They usually turn them around quickly.

CR

Sport_Pilot

That looks like a general overview of license requirements. Nothing there about R/C. The FCC got rid of a bunch of license requirments years ago, the only ones left that require repair are a Commercial Radio license, Broadcast, Cable, International, and Amatur (not sure the license is required for repair though). Non of those cover R/C. If you read the reg close it says nothing about a license, only that the repair person be certified.

Forgot Maritime, no that doesn't R/C either, not even the boats.

Sport_Pilot

I have never ever seen any glue on a TX crystal, it's BS. I have pulled them out to be double sure that the trainer radio is not trasmitting. No glue ever. Sombody came up with this BS to pretend they know what they are talking about.

Sport_Pilot

Yeah here it is.

I do not know the licensing requirements to be able to swap Tx crystals. I'd guess the FCC web site has the info buried somewhere.

And before you say the warning negates that, the warning is about transmitting without a license, not repair. Check out the other license if you will, there is nothing for R/C

JohnW

My Feedback: (6)

Sport, this thread is 3years old. Why bring it back? If you would have bothered following the link in this thread, where I posted 3 years ago that this stuff is spelled out VERY CLEARLY in part 95.221, you wouldn’t need to post three times in a row in a 3 year old thread.

http://edocket.access.gpo.gov/cfr_20...7cfr95.221.pdf

Charley

My Feedback: (2)

Your link addresses repair and modification issues. The scope is beyond a simple Xtal swap. It's typical governmentalese; can be interpreted any way you please.

So what's your point?

CR

BarracudaHockey

My Feedback: (11)

Changing the crystal is modifying the frequency determining components.

Sport_Pilot

I posted this because it came up on the beginner forum. That reg you quoted is clear as mud. Anyone who has taken an electronic course can say he is qualified. There is no FCC license for the private land moble services as those license were done away years ago, the link I posted proved that. I thought since I found that site I would bring it up again.

Sport_Pilot

No they are completly intact, you have simply swapped one. IMO its not a modification unless it is transmitting on the wrong frequency. I wonder if it really does, I have heard the factory simply slaps a crystal in when leaving the factory. Don't know if they check the frequency or not. I have swapped my crystal and range was good and no interferance with adjacent frequencies. But I only checked by putting two crystal of each frequecy to each side. I wasn't brave enough to actually use it so I sent it to Radio South. BTW the post above about Tony Stillman, he said essentially the same thing, but that I would be better off if he serviced it. Since the transmitter was getting a bit old I decided to send it to him. Fine man enjoyed talking to him.

BarracudaHockey

My Feedback: (11)

I think the point is that you need the equipment and know how to ensure the transmitter is on frequency and within specs when you're done with it.

LSF2298

My Feedback: (4)

The crystal is not the sole frequency determining component in the RF Circuit. There are several other components in the circuit so you are in fact making a modification to the Frequency Determinig Circuit by changing the crystal. Your lack of this knowledge demonstrates that you do not have the skills, let alone the equipment to be changing crystals and retuning the Frequency Determining Circuit.

Sport_Pilot

You lack of knowledge includes the meaning of modification. Look it up, changing a frequecy crystal that is made and factory certified for that radio is not a modification. However if it is off frequency that may be a differant thing. The fact is I never said you should change the crystal without the skills (which I have) or the equipment (which I don't have). I suggest you go back and reread my posts with an open dictionary and maybe the FCC regs to include simple definitions.

Sport_Pilot

Yes that I think is the meaning, but who does the certification? I think someone at the FCC should rewrite this. If factory certified, then it should say so. Otherwise the graduate of Podunk technical school could claim they are certified.

KB9STD

My Feedback: (1)

"IMO its not a modification unless it is transmitting on the wrong frequency"
Well If You bought a "CHANNEL20" transmitter,and changed the crystal in it to repair it. I assume that the crystal is being replaced to "repair" it,Because You have stated that it IS NOT a modification. IF it then transmits on any frequency other than channel 20,it is transmitting "ON THE WRONG FREQUENCY".
You MODIFIED it,and the act was "Against FCC regulations".They are NOT laws,only regulations.AND if caught,You WON"T be taken to court.You will be fined by the FCC themselves.It's like fighting the IRS,but Worse!

Sport_Pilot

If it is transmitting on the frequency marked on the crystal then it is transmitting on the correct frequency, the transmitter is not marked with a specific frequency. Look up modifications in the FCC regs, I think you will find the correct definition there. Regulations are backed by law, the law allows the FCC to fine you as the police can fine you without a court, but you can take it to court and open another can of worms. IMO the FCC doesn't currently care as the bands adjacent to ours are not used much. When was the last time you saw someone with a beeper? The AMA should be trying to claim these frequencies.

BarracudaHockey

My Feedback: (11)

There's commercial users sandwhiched between our channels. This is why the restriction only exists on 72mhz and doesn't effect the ham or car guys.

They pay for the use of the band, we, on the other hand, are freeloaders.

Interfere with the paying users, and I can promise you, they will find you and fine you. It's 10 grand per occurance. Versus 30 dollars to get your radio tuned properly. This is also a chance to get it checked out and peaked.

The fact that you know something about the process is great. The average user shouldn't be messing with it.

JohnW

My Feedback: (6)

Sport, I don't see how you could have read the reg I posted based on what you have posted. It very clearly says you must certified by an organization or committee representative of users in those services to adjust the TX. The organization or committee does the certification.

Again, like I posted in the other thread in beginners, I mean no disrespect, but the problem is not the FCC regs, but your misinterpretation and lack of full understanding on how the regs work. There is nothing broke in the regs here… don’t fiddle with the TX xtal… I think most can understand that.

carrellh

Sport, call BS if you want, but you are incorrect.

Both of my Futaba 6XAS transmitters had a tiny drop of what looks like hot glue holding the crystal cap to the transmitter case. It popped loose with very little effort but that does not change the fact that it was glued in.

I couldn't get a great picture from less than a foot away but the glue drop is there.

But, I guess I'm just pretending to know what I'm writing.

LSF2298

My Feedback: (4)

Sport, my knowledge is certified by the FCC with my General License, K4HLH, now tell me what is your certification. And I'll tell you again, the crystal is not the sole determining factor of the Frequency Determination Circuit.l

804

My Feedback: (1)

My JR Quattro and xp662, both about 5 yrs old, had glue drops on the tx crystals. No BS.

Sport_Pilot

It is clear as mud since it didn't name the organization or committee. I guess I can organize one and certify myself? You don't know so why do you insist?

Sport_Pilot

Since that doesn't cover R/C radio's it hardly makes you an expert since you were not tested on R/C.

http://wireless.fcc.gov/commoperators/pg.html


And your point is?