isnt a crystal a crystal?
08-12-2005, 10:41 AM
#51
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RE: isnt a crystal a crystal?
Very good write up Apteryx. The only point I slightly dissagree with is item 4. You can slightly pull a crystal with either capacitance or inductance, in fact this is what is often done to get the last bit of calibration.
08-12-2005, 01:09 PM
#52
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RE: isnt a crystal a crystal?
Personally, I have experienced interference from a guy who swapped TX crystals, and I won't do it to be absolutely safe. As for the regulations, its posted as a sticky at RC Groups
http://www.rcgroups.com/forums/showthread.php?t=94580
http://www.rcgroups.com/forums/showthread.php?t=94580
08-12-2005, 02:51 PM
#53
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RE: isnt a crystal a crystal?
Taken from the FCC:
"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."
What is the relevant "organization or committee representative of users" for RC? The AMA? The FCC?
What does it take to legally change a transmitter crystal?
Just an FCC general commercial license - e.g. someone working out of his garage with a license?
An FCC approved repair facility, with FCC approved test equipment, like the FAA does for avionics?
A repair facility approved by the radio manufacturer?
A repair facility approved by the AMA?
Does the test equipment need to be calibrated on a schedule by a certified cal lab?
Etc, etc.
How do we know that a repair facility we send our radio to to change a crystal is indeed legal? This seems to be a huge grey area.
"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."
What is the relevant "organization or committee representative of users" for RC? The AMA? The FCC?
What does it take to legally change a transmitter crystal?
Just an FCC general commercial license - e.g. someone working out of his garage with a license?
An FCC approved repair facility, with FCC approved test equipment, like the FAA does for avionics?
A repair facility approved by the radio manufacturer?
A repair facility approved by the AMA?
Does the test equipment need to be calibrated on a schedule by a certified cal lab?
Etc, etc.
How do we know that a repair facility we send our radio to to change a crystal is indeed legal? This seems to be a huge grey area.
08-12-2005, 03:34 PM
#54
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RE: isnt a crystal a crystal?
Both of my parents (mom retired about 4 years ago, step-dad still employed) work(ed) for FCC field offices in Grand Island, NE and now New Orleans, LA. My mother worked in regulation enforcement, i.e. she prepared the data the government lawyers used to nail violators. She knows the regs inside and out and how they are interpreted. My step-dad is an engineer and is responsible for gathering the technical data, goes on raids, etc.
I've asked my parents the exact questions posed in this thread as per FCC regs. The short version is the user cannot change the TX frequency… period.
Keep in mind the regs are broad. There are many commercial RC uses that are also covered by the same regs that affect us, i.e RC cranes and other construction RC stuff.
Just because crystals are sold and are easily accessible on the TX does NOT mean it is OK to change them. There is no liability on the reseller for selling the crystals as selling crystals is not illegal, but this does not mean you can legally use the crystal however you like. I.E., guns and bullets are legal to sell and own, but that does not mean you can use the gun however you like.
As for the xtal being easily accessible, that is a sticky point. The FCC often allows manufactures to make such components easily accessible to help lower their costs and speed up time to market. The problem is if users abuse this easy access. In serious cases, the FCC will require the manufacturer to redesign equipment such that the user cannot easily access the naughty bits. One recent pointed out to me was a hand held 2-way radio that could be reprogrammed by the user for various frequencies, many of which required licenses. The radio was sold for both public non-licensed and licensed freqs, hence the ability to change. Of course, users eventually found the freq change menu and they were xmitting on freqs they shouldn’t be on, so the FCC slapped the manufacturer who had to reprogram existing radios to lock out the freq change feature and make future radios impossible for users to change.
As to the technical stuff... Xtal change requires a recheck of compliance which involves testing to specific standards. It's clearly in the FCC regs, but you have to read multiple sections to find the technical compliance figures. No testing, no compliance and you can't use the TX; hence the TX xtal can only be changed by persons or organizations that can verify compliance. Range check is NOT a compliance test. You need equipment used for tuning and checking RF output, etc. With synth and modular systems, it is the modules that must meet compliance. Since you change the whole module (or redial a freq on a synth), these are the only legal way for typical users to change their TX freq by themselves.
Cheers
I've asked my parents the exact questions posed in this thread as per FCC regs. The short version is the user cannot change the TX frequency… period.
Keep in mind the regs are broad. There are many commercial RC uses that are also covered by the same regs that affect us, i.e RC cranes and other construction RC stuff.
Just because crystals are sold and are easily accessible on the TX does NOT mean it is OK to change them. There is no liability on the reseller for selling the crystals as selling crystals is not illegal, but this does not mean you can legally use the crystal however you like. I.E., guns and bullets are legal to sell and own, but that does not mean you can use the gun however you like.
As for the xtal being easily accessible, that is a sticky point. The FCC often allows manufactures to make such components easily accessible to help lower their costs and speed up time to market. The problem is if users abuse this easy access. In serious cases, the FCC will require the manufacturer to redesign equipment such that the user cannot easily access the naughty bits. One recent pointed out to me was a hand held 2-way radio that could be reprogrammed by the user for various frequencies, many of which required licenses. The radio was sold for both public non-licensed and licensed freqs, hence the ability to change. Of course, users eventually found the freq change menu and they were xmitting on freqs they shouldn’t be on, so the FCC slapped the manufacturer who had to reprogram existing radios to lock out the freq change feature and make future radios impossible for users to change.
As to the technical stuff... Xtal change requires a recheck of compliance which involves testing to specific standards. It's clearly in the FCC regs, but you have to read multiple sections to find the technical compliance figures. No testing, no compliance and you can't use the TX; hence the TX xtal can only be changed by persons or organizations that can verify compliance. Range check is NOT a compliance test. You need equipment used for tuning and checking RF output, etc. With synth and modular systems, it is the modules that must meet compliance. Since you change the whole module (or redial a freq on a synth), these are the only legal way for typical users to change their TX freq by themselves.
Cheers
08-13-2005, 10:09 AM
#55
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RE: isnt a crystal a crystal?
Thanks JohnW. That's very good information.
Could you please help clarify the meaning in the context of hobby RC 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"?
The reason I ask is that I work with an engineer who designs non-RC receivers for a living and is also an avid RCer. He is intimately familiar with the design and operation of RC FM receivers, in fact he worked with Fred Marks at one time. We have access through our employer to high quality test equipment, which is maintained on a rigorous calibration schedule. I hold the FCC general commercial license. Clearly we are capable of properly changing the crystal in an RC transmitter. The question is legally, can we change the crystal on my transmitter? I think the answer is NO, since we have not been certified as technically qualified by a committee representative of RC users. I'm not even sure there is such a committee in the case of hobby RC.
Thanks!
Could you please help clarify the meaning in the context of hobby RC 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"?
The reason I ask is that I work with an engineer who designs non-RC receivers for a living and is also an avid RCer. He is intimately familiar with the design and operation of RC FM receivers, in fact he worked with Fred Marks at one time. We have access through our employer to high quality test equipment, which is maintained on a rigorous calibration schedule. I hold the FCC general commercial license. Clearly we are capable of properly changing the crystal in an RC transmitter. The question is legally, can we change the crystal on my transmitter? I think the answer is NO, since we have not been certified as technically qualified by a committee representative of RC users. I'm not even sure there is such a committee in the case of hobby RC.
Thanks!
08-17-2005, 06:30 PM
#56
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RE: isnt a crystal a crystal?
Again, you can buy RC controlled concrete power trowels, cranes, other equipment. The plane hobby is just one type of RC use out of many as far as the FCC is concerned. Out of the 100 sections in Part 95, only one or two address RC aircraft specifically. Part 95 even covers CB radios.
The key is complaince. The equipment must remain complaint. Changing the Xtal instantly voids compliance. Can't remember what part, but it is in there somewhere. To regain compliance after a xtal change, it must be tested as per the technical standards in subpart E. Subpart "E" is labeled... it is section 95.600 - 95.699
I don't see what the problem is understanding 95.221.b... It seems pretty clear to me but my guess is you're not used to reading legal docs. Here is the part...
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.
It clearly states that you should be certified to perform these types of repairs or adjustments, or you must be working under the supervision of someone who is certified. The certification must come from a reglatory committe or organization representative of such services. The service is radio repair, not RC user or the AMA, etc. This means you need to be certified to perform radio repair by a organization or comittee that represents radio repair men. I'm sure there is a standards organazation that teaches, tests and certifies radio repair men. I am not in that field so I don't know who that would be... maybe the EIA/TIA?
The key is complaince. The equipment must remain complaint. Changing the Xtal instantly voids compliance. Can't remember what part, but it is in there somewhere. To regain compliance after a xtal change, it must be tested as per the technical standards in subpart E. Subpart "E" is labeled... it is section 95.600 - 95.699
I don't see what the problem is understanding 95.221.b... It seems pretty clear to me but my guess is you're not used to reading legal docs. Here is the part...
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.
It clearly states that you should be certified to perform these types of repairs or adjustments, or you must be working under the supervision of someone who is certified. The certification must come from a reglatory committe or organization representative of such services. The service is radio repair, not RC user or the AMA, etc. This means you need to be certified to perform radio repair by a organization or comittee that represents radio repair men. I'm sure there is a standards organazation that teaches, tests and certifies radio repair men. I am not in that field so I don't know who that would be... maybe the EIA/TIA?
08-22-2005, 11:11 AM
#58
My Feedback: (2)
RE: isnt a crystal a crystal?
Well, the FCC once licensed technicians who maintained and repaired radio transmitters. About 20 years ago the FCC more or less stepped out of the picture and asked industries to basically self regulate.
As far as I know there is presently no organization that licenses or certifies techicians who maintain and repair radio transmitters.
The FCC does get involved when a new transmitter is designed, prior to production and release to the marketplace. Radio equipment must pass a rigorous certification process that includes testing for intentional and unintentional RF emissions. This is performed by commercial laboratories who specialize in the business, and costs the manufacturer many thousands of dollars. Our RC transmitters go through this certification, and I expect the manufacturer is required to demonstrate compliance on each of the RC channels.
I believe that channel changes made in the field on a particular transmitter do not require re-certification, as the product has already been certified for all RC frequencies by the manufacturer. What is required is that the transmitter be tweaked to exactly the right frequency with the new crystal and that the FM deviation and spectrum be checked for proper operation. Clearly the FCC intends that there be assurance that changes are made only by qualified technicians.
What it takes to be considered qualified remains a mystery. It may just be a grey area in FCC regs that has never been worked out.
As far as I know there is presently no organization that licenses or certifies techicians who maintain and repair radio transmitters.
The FCC does get involved when a new transmitter is designed, prior to production and release to the marketplace. Radio equipment must pass a rigorous certification process that includes testing for intentional and unintentional RF emissions. This is performed by commercial laboratories who specialize in the business, and costs the manufacturer many thousands of dollars. Our RC transmitters go through this certification, and I expect the manufacturer is required to demonstrate compliance on each of the RC channels.
I believe that channel changes made in the field on a particular transmitter do not require re-certification, as the product has already been certified for all RC frequencies by the manufacturer. What is required is that the transmitter be tweaked to exactly the right frequency with the new crystal and that the FM deviation and spectrum be checked for proper operation. Clearly the FCC intends that there be assurance that changes are made only by qualified technicians.
What it takes to be considered qualified remains a mystery. It may just be a grey area in FCC regs that has never been worked out.
08-23-2005, 01:59 PM
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RE: isnt a crystal a crystal?
JPMacG, as per certification, that's my basic understanding too. The regs indicate the TX must remain compliant after a XTal change. Obviously the TX does not need a full lab certification such as what is performed preproduction. I believe the FCC just wants some reasonable assurance that Xtal changes are performed properly and the tuning of the equipment is checked after the change. Tuning a TX is beyond an "end user" task so they mention it should be performed by a qualified technician.
Probably never get the FCC to officially admit this, but if you are knowledgeable in tuning TX's, I believe you could legally perform the change yourself as long as you test tuning. The actual regs say the work "should" be performed by a certified tech, not that it "shall" or "must."
Probably never get the FCC to officially admit this, but if you are knowledgeable in tuning TX's, I believe you could legally perform the change yourself as long as you test tuning. The actual regs say the work "should" be performed by a certified tech, not that it "shall" or "must."
08-23-2005, 11:11 PM
#60
RE: isnt a crystal a crystal?
Man, I brought this issue up about 2 years ago and I think you have covered every side of the aurgement. I myself have knowledge of RF circuits and understand the bad things that can happen when you go from channel 1 to channel 60 without retuning the RF ckt and finals.
I am sure that the manufacturs want to protect there product and market image. However there are several indivudalsand businesses that are trained and have the proper legal qualifications to do the job just as good or maybe better that the factory and still be 100% legal in doing it.
first of all in most cases you wont be able to buy the xmitter crystal (I have tried) from Hitec, Futaba, etc. So this leaves the Joe sixpack to experiment on his own. Maybe he has a old 4 channel transmitter on freq 30 and all his receiver are on 30, buys a 6 channel xmitter on 57 of Ebay and swaps the crystals. Now his new xmitter will work with all his older receivers. who is going to stop him and who is going to know he did it.
Now, I have been told that a frequency change of 1 or 2 channels up or down will not really make that much of a difference. Since I dont own a spectrum analyzer I can't tell you if that is a true statement. In my Amateur radio days I would say that very little truning of the RF finals was needed when I did go up or down by a few clicks.
As I remember 2 years ago when I borught this issue up on this forum, I got positive and negative responses. After about 2 weeks, I figured that no one was going to give a inch on this issue. Some were dictating the AMA rules, FCC rules and some were taking the side of I know what I'm doing.
Thanks for bringing this issue up again (can't remember who started it) but it brought a chuckle when I started reading some of the boiler plate responses that I remembered from long ago.
Keep it up, this is better that watching tv.
My $.02 worth.
Larry Barnes
I am sure that the manufacturs want to protect there product and market image. However there are several indivudalsand businesses that are trained and have the proper legal qualifications to do the job just as good or maybe better that the factory and still be 100% legal in doing it.
first of all in most cases you wont be able to buy the xmitter crystal (I have tried) from Hitec, Futaba, etc. So this leaves the Joe sixpack to experiment on his own. Maybe he has a old 4 channel transmitter on freq 30 and all his receiver are on 30, buys a 6 channel xmitter on 57 of Ebay and swaps the crystals. Now his new xmitter will work with all his older receivers. who is going to stop him and who is going to know he did it.
Now, I have been told that a frequency change of 1 or 2 channels up or down will not really make that much of a difference. Since I dont own a spectrum analyzer I can't tell you if that is a true statement. In my Amateur radio days I would say that very little truning of the RF finals was needed when I did go up or down by a few clicks.
As I remember 2 years ago when I borught this issue up on this forum, I got positive and negative responses. After about 2 weeks, I figured that no one was going to give a inch on this issue. Some were dictating the AMA rules, FCC rules and some were taking the side of I know what I'm doing.
Thanks for bringing this issue up again (can't remember who started it) but it brought a chuckle when I started reading some of the boiler plate responses that I remembered from long ago.
Keep it up, this is better that watching tv.
My $.02 worth.
Larry Barnes
08-24-2005, 12:03 AM
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RE: isnt a crystal a crystal?
Yeah, Larry I agree it is one of those things that come up from time to time and at times entertaining. There are more that several threads on both RCU and RC Groups and other forums as well. RC Groups even has a sticky thread in their radio forum. Its just one those things that is easier to deny, especially it is legal in other countries, (but then again most don't have the wide band that we do). Additionally, I think much of the blame can be put on the radio manufacturers package their products. If they had soldered the crystal on the circuit board out of view, the discussion would come up much less frequently. I think the least manufacturers could do is to glue the TX crystal a bit more securely for it is much to easy to pull out, and stop selling TX crystals to the general public. Personally I have seen problems arise but I think 95% of the time nothing happens so it is easier to close one's eye's
For a change of pace how about a discussion on ARFs/Kits, learning with or without an instructor, or electric/gas discussion?
For a change of pace how about a discussion on ARFs/Kits, learning with or without an instructor, or electric/gas discussion?
08-24-2005, 02:59 PM
#62
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RE: isnt a crystal a crystal?
Im the one who started it, and didnt really mean for it to escalate to this level. I could have done with just a "get a new rx xtal" answer, and have been done with it. but i didnt, so i learned some more about all this rc stuff, which I enjoy. I do think its kinda funny how people want to fight about it, but thats their business.
for the change, I tought myself how to fly, or rather terra ferma did, on a rtf electric. been flyin for a year and I feel like my thumbs are pretty well suited to fly just fine. Im just glad I was cheap and got the plane I did, because wings were only 7 bucks, and it took one hell of a beating.
for the change, I tought myself how to fly, or rather terra ferma did, on a rtf electric. been flyin for a year and I feel like my thumbs are pretty well suited to fly just fine. Im just glad I was cheap and got the plane I did, because wings were only 7 bucks, and it took one hell of a beating.
