Crystals Failure?
10-13-2008 | 10:48 AM
#1
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From: Verde Santa Fe,
AZ
Crystals Failure?
Plane Big Stik 60.... 2 pervious flights, same crystals.... Yesterday after pre-flight cheked O.K. I taxied onto the runway and gave her full power for take-off "Nothing" the elevator would not lift her off, tried to shut-down the power and again "Nothing" and into the wire fence around our field. 80% destroyed..... Later my buddy, 30+ year flyer, checked the plane out. We found that with my original crystals nothing would work, we then changed to another frequency "Crystals" in the radio and receiver and the servos, etc, would work. Back to my original crystals and again "Nothing".
We believe that the receiver crystal failed!
Any idea's, suggestions, or does anyone think our "Autopsy" was correct??
Thanks [&o]
We believe that the receiver crystal failed!
Any idea's, suggestions, or does anyone think our "Autopsy" was correct??
Thanks [&o]
10-13-2008 | 11:07 AM
#3
RCU Forum Manager/Admin
My Feedback: (9)
RE: Crystals Failure?
It sounds like you may have indeed had a crystal failure.
However, your changing the crystal in the transmitter was illegal. Transmitter crystals can only be changed by a licensed shop that can adjust the power output of the radio. Even changing out a crystal on the same channel must be done by a shop as crystals can vary even when they are on the same channel.
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
However, your changing the crystal in the transmitter was illegal. Transmitter crystals can only be changed by a licensed shop that can adjust the power output of the radio. Even changing out a crystal on the same channel must be done by a shop as crystals can vary even when they are on the same channel.
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
How do I change the frequency of my transmitter?
For a unit with crystals: We CANNOT recommend changing crystals to a different frequency. Changing the crystal on your transmitter is illegal unless you have the proper license. The FCC has established guidelines for the modeler's safety and for the safety of spectators. For safety and FCC reasons we must request that both TX and RX be sent to the service center to ensure proper crystal change and retuning to the new frequency. Crystal based radios cannot be converted to another band without parts replacement, and may not be able to be converted at all. Certain radios can be converted, for example, from 72 to 75MHz. Please contact the service center for any other conversions.
The applicable Federal Regulation is as follows:
TITLE 47—TELECOMMUNICATION COMMISSION (CONTINUED)
PART 95—PERSONAL RADIO SERVICES
Subpart E—Technical Regulations
Sec. 95.645 Control accessibility.
(a) No control, switch or other type of adjustment which, when
manipulated, can result in a violation of the rules shall be accessible
from the transmitter operating panel or from exterior of the transmitter
enclosure.
(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.
For a unit with crystals: We CANNOT recommend changing crystals to a different frequency. Changing the crystal on your transmitter is illegal unless you have the proper license. The FCC has established guidelines for the modeler's safety and for the safety of spectators. For safety and FCC reasons we must request that both TX and RX be sent to the service center to ensure proper crystal change and retuning to the new frequency. Crystal based radios cannot be converted to another band without parts replacement, and may not be able to be converted at all. Certain radios can be converted, for example, from 72 to 75MHz. Please contact the service center for any other conversions.
The applicable Federal Regulation is as follows:
TITLE 47—TELECOMMUNICATION COMMISSION (CONTINUED)
PART 95—PERSONAL RADIO SERVICES
Subpart E—Technical Regulations
Sec. 95.645 Control accessibility.
(a) No control, switch or other type of adjustment which, when
manipulated, can result in a violation of the rules shall be accessible
from the transmitter operating panel or from exterior of the transmitter
enclosure.
(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.
Copied from FCC regulations concerning this issue
[Code of Federal Regulations]
[Title 47, Volume 5]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR95.221]
[Page 539]
TITLE 47TELECOMMUNICATION CHAPTER IFEDERAL COMMUNICATIONS COMMISSION (CONTINUED)
PART 95_PERSONAL RADIO SERVICESTable of Contents
Subpart C_Radio Control (R/C) Radio Service
Sec. 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.
(c) Except as provided in paragraph
(d) of this section, each internal repair and each internal adjustment of an R/C transmitter in which signals are transmitted must be made using a nonradiating (``dummy'') antenna. (d) Brief test signals (signals not longer than one minute during any five minute period) using a radiating antenna may be transmitted in order to:
(1) Adjust a transmitter to an antenna;
(2) Detect or measure radiation of energy other than the intended signal; or
(3) Tune a receiver to your R/C transmitter.
(Secs. 4(i) and 303(r), Communications Act of 1934, as amended, 47 U.S.C. 154(i) and 303(r), and sec. 553 of the Administrative Procedures Act, 5 U.S.C. 553) [48 FR 24890, June 3, 1983, as amended at 49 FR 20673, May 16, 1984; 63 FR 36610, July 7, 1998]
[Title 47, Volume 5]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR95.221]
[Page 539]
TITLE 47TELECOMMUNICATION CHAPTER IFEDERAL COMMUNICATIONS COMMISSION (CONTINUED)
PART 95_PERSONAL RADIO SERVICESTable of Contents
Subpart C_Radio Control (R/C) Radio Service
Sec. 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.
(c) Except as provided in paragraph
(d) of this section, each internal repair and each internal adjustment of an R/C transmitter in which signals are transmitted must be made using a nonradiating (``dummy'') antenna. (d) Brief test signals (signals not longer than one minute during any five minute period) using a radiating antenna may be transmitted in order to:
(1) Adjust a transmitter to an antenna;
(2) Detect or measure radiation of energy other than the intended signal; or
(3) Tune a receiver to your R/C transmitter.
(Secs. 4(i) and 303(r), Communications Act of 1934, as amended, 47 U.S.C. 154(i) and 303(r), and sec. 553 of the Administrative Procedures Act, 5 U.S.C. 553) [48 FR 24890, June 3, 1983, as amended at 49 FR 20673, May 16, 1984; 63 FR 36610, July 7, 1998]
[Code of Federal Regulations]
[Title 47, Volume 5]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR95.222]
[Page 539-540]
TITLE 47TELECOMMUNICATION
CHAPTER IFEDERAL COMMUNICATIONS
COMMISSION (CONTINUED)
PART 95_PERSONAL RADIO SERVICESTable of Contents
Subpart C_Radio Control (R/C) Radio Service
Sec. 95.222 (R/C Rule 22) May I make any changes to my R/C station transmitter?
(a) You must not make or have anyone else make an internal modification to your R/C transmitter.
(b) Internal modification does not include:
(1) Repair or servicing of an R/C station transmitter (see R/C Rule 21, Sec. 95.221); or
(2) Changing plug-in modules which were certificated as part of your R/C transmitter.
(c) You must not operate an R/C transmitter which has been modified by anyone in any way, including modification to operate on unauthorized frequencies or with illegal power. (See R/C Rules 9 and 10, Sec. Sec. 95.209 and 95.210.)
[48 FR 24894, June 3, 1983, as amended at 63 FR 36610, July 7, 1998]
[Title 47, Volume 5]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR95.222]
[Page 539-540]
TITLE 47TELECOMMUNICATION
CHAPTER IFEDERAL COMMUNICATIONS
COMMISSION (CONTINUED)
PART 95_PERSONAL RADIO SERVICESTable of Contents
Subpart C_Radio Control (R/C) Radio Service
Sec. 95.222 (R/C Rule 22) May I make any changes to my R/C station transmitter?
(a) You must not make or have anyone else make an internal modification to your R/C transmitter.
(b) Internal modification does not include:
(1) Repair or servicing of an R/C station transmitter (see R/C Rule 21, Sec. 95.221); or
(2) Changing plug-in modules which were certificated as part of your R/C transmitter.
(c) You must not operate an R/C transmitter which has been modified by anyone in any way, including modification to operate on unauthorized frequencies or with illegal power. (See R/C Rules 9 and 10, Sec. Sec. 95.209 and 95.210.)
[48 FR 24894, June 3, 1983, as amended at 63 FR 36610, July 7, 1998]
[Code of Federal Regulations]
[Title 47, Volume 5]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR95.645]
[Page 561]
TITLE 47TELECOMMUNICATION
CHAPTER IFEDERAL COMMUNICATIONS
COMMISSION (CONTINUED)
PART 95_PERSONAL RADIO SERVICESTable of Contents
Subpart E_Technical Regulations
Sec. 95.645 Control accessibility.
(a) No control, switch or other type of adjustment which, when manipulated, can result in a violation of the rules shall be accessible
from the transmitter operating panel or from exterior of the transmitter enclosure.
(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.
[53 FR 36789, Sept. 22, 1988. Redesignated at 61 FR 28769, June 6, 1996, and further redesignated at 61 FR 46567, Sept. 4, 1996; 63 FR 36610, July 7, 1998]
[Title 47, Volume 5]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR95.645]
[Page 561]
TITLE 47TELECOMMUNICATION
CHAPTER IFEDERAL COMMUNICATIONS
COMMISSION (CONTINUED)
PART 95_PERSONAL RADIO SERVICESTable of Contents
Subpart E_Technical Regulations
Sec. 95.645 Control accessibility.
(a) No control, switch or other type of adjustment which, when manipulated, can result in a violation of the rules shall be accessible
from the transmitter operating panel or from exterior of the transmitter enclosure.
(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.
[53 FR 36789, Sept. 22, 1988. Redesignated at 61 FR 28769, June 6, 1996, and further redesignated at 61 FR 46567, Sept. 4, 1996; 63 FR 36610, July 7, 1998]
10-13-2008 | 11:34 AM
#4
RE: Crystals Failure?
It is a rare failure, mostly associated to exposition of electronics to vibrations or extreme heat.
I would check the working conditions of the receiver in that regard.
I believe the legal issue only applies to the transmitters.
I would recommend replacing the receiver crystal first, then, if there is no communication, just send the transmitter and receiver to an authorized service shop.
Regards!
I would check the working conditions of the receiver in that regard.
I believe the legal issue only applies to the transmitters.
I would recommend replacing the receiver crystal first, then, if there is no communication, just send the transmitter and receiver to an authorized service shop.
Regards!
10-13-2008 | 11:42 AM
#5
RCU Forum Manager/Admin
My Feedback: (9)
RE: Crystals Failure?
ORIGINAL: lnewqban
I believe the legal issue only applies to the transmitters.
I believe the legal issue only applies to the transmitters.
Ken
10-13-2008 | 11:54 AM
#7
RE: Crystals Failure?
I have no problem with him swapping the TX crystal for a BRIEF test like he did as long as he made sure no other pilots were flying at the time. Improper crystals CAN (but not always) do strange things in the way of spurious signals. Swapping in a friends RX crystal and seeing if the friends TX could control the plane would be a valid test. (TX must be a compatible type of course).
10-13-2008 | 04:53 PM
#8
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From: Verde Santa Fe,
AZ
RE: Crystals Failure?
Sorry! I guess I did-not explain myself correctly........ I took another crystal from another plane, same channel, and it indeed worked in the Stik!
Thanks guys[
]
Thanks guys[
]
10-14-2008 | 07:57 AM
#9
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From: Ignacio,
CO
RE: Crystals Failure?
Sorry to hear about your Big Stik.[:@] Just out of curiosity, had that receiver been through a crash before? I put a crashed receiver in another plane and everything was fine until the first time I started the engine. I ran it up to full throttle and then.... nothing. The engine is screaming and I have no way to shut down. Fortunately the plane was restrained and I pinched the fuel line to kill the engine. Sure enough, a new receiver crystal solved the problem but I always wonder what might have happened if that crystal had held in there for a few more minutes. Probably nothing good.
10-14-2008 | 08:29 AM
#10
Senior Member
My Feedback: (1)
RE: Crystals Failure?
ORIGINAL: Deadeye
Only way to be 100% sure is to replace only the RX crystal. I have had one in flight RX crystal failure. Airframe was destroyed.
Only way to be 100% sure is to replace only the RX crystal. I have had one in flight RX crystal failure. Airframe was destroyed.
10-14-2008 | 09:30 AM
#12
RE: Crystals Failure?
How do I change the frequency of my transmitter?
For a unit with crystals: We CANNOT recommend changing crystals to a different frequency. Changing the crystal on your transmitter is illegal unless you have the proper license. The FCC has established guidelines for the modeler's safety and for the safety of spectators. For safety and FCC reasons we must request that both TX and RX be sent to the service center to ensure proper crystal change and retuning to the new frequency. Crystal based radios cannot be converted to another band without parts replacement, and may not be able to be converted at all. Certain radios can be converted, for example, from 72 to 75MHz. Please contact the service center for any other conversions.
The applicable Federal Regulation is as follows:
TITLE 47—TELECOMMUNICATION COMMISSION (CONTINUED)
PART 95—PERSONAL RADIO SERVICES
Subpart E—Technical Regulations
Sec. 95.645 Control accessibility.
(a) No control, switch or other type of adjustment which, when
manipulated, can result in a violation of the rules shall be accessible
from the transmitter operating panel or from exterior of the transmitter
enclosure.
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.
PART 95—PERSONAL RADIO SERVICES
Subpart E—Technical Regulations
Sec. 95.645 Control accessibility.
(a) No control, switch or other type of adjustment which, when
manipulated, can result in a violation of the rules shall be accessible
from the transmitter operating panel or from exterior of the transmitter
enclosure.
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.
10-14-2008 | 09:38 AM
#13
RCU Forum Manager/Admin
My Feedback: (9)
RE: Crystals Failure?
ORIGINAL: Sport_Pilot
Yet the FCC has been certifying them with the crystal easily accessable from the front, therefore changing them also legal?
Yet the FCC has been certifying them with the crystal easily accessable from the front, therefore changing them also legal?
Ken
10-14-2008 | 09:58 AM
#14
Senior Member
RE: Crystals Failure?
The most common cause of a crystal failure is mechanical shock. Remember that there are two or more crystals in each receiver although only one is easily replaceable (the other is permanently soldered into the circuit). Either can be damaged in a hard landing or crash as they are just a piece of quartz ground to size and suspended between two post or wires inside the metal can they are usually enclosed in. The crystal can fracture or one of the leads can be cracked and open up under vibration (engine running). If replacing the plug in crystal does not fix the problem, you could still have a broken crystal (the other one) causing your problem.
10-14-2008 | 10:09 AM
#15
RE: Crystals Failure?
ORIGINAL: Sport_Pilot
How do I change the frequency of my transmitter?
For a unit with crystals: We CANNOT recommend changing crystals to a different frequency. Changing the crystal on your transmitter is illegal unless you have the proper license. The FCC has established guidelines for the modeler's safety and for the safety of spectators. For safety and FCC reasons we must request that both TX and RX be sent to the service center to ensure proper crystal change and retuning to the new frequency. Crystal based radios cannot be converted to another band without parts replacement, and may not be able to be converted at all. Certain radios can be converted, for example, from 72 to 75MHz. Please contact the service center for any other conversions.
The applicable Federal Regulation is as follows:
This is outdated as the license is no longer required, unless recently re-established.
Yet the FCC has been certifying them with the crystal easily accessable from the front, therefore changing them also legal?
How do I change the frequency of my transmitter?
For a unit with crystals: We CANNOT recommend changing crystals to a different frequency. Changing the crystal on your transmitter is illegal unless you have the proper license. The FCC has established guidelines for the modeler's safety and for the safety of spectators. For safety and FCC reasons we must request that both TX and RX be sent to the service center to ensure proper crystal change and retuning to the new frequency. Crystal based radios cannot be converted to another band without parts replacement, and may not be able to be converted at all. Certain radios can be converted, for example, from 72 to 75MHz. Please contact the service center for any other conversions.
The applicable Federal Regulation is as follows:
TITLE 47—TELECOMMUNICATION COMMISSION (CONTINUED)
PART 95—PERSONAL RADIO SERVICES
Subpart E—Technical Regulations
Sec. 95.645 Control accessibility.
(a) No control, switch or other type of adjustment which, when
manipulated, can result in a violation of the rules shall be accessible
from the transmitter operating panel or from exterior of the transmitter
enclosure.
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.
PART 95—PERSONAL RADIO SERVICES
Subpart E—Technical Regulations
Sec. 95.645 Control accessibility.
(a) No control, switch or other type of adjustment which, when
manipulated, can result in a violation of the rules shall be accessible
from the transmitter operating panel or from exterior of the transmitter
enclosure.
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.
As for the front mounted or easy access crystals (not modules) these are because these same units are sold world-wide where the same regulations do not apply. Nor are the radio bands as jammed with people all trying to use the same space. Modules are a totally different subject and have different rules that allow their swapping as long as certain conditions are met.
10-14-2008 | 11:04 AM
#16
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From: Poolesville, MD
RE: Crystals Failure?
ORIGINAL: bruce88123
I have no problem with him swapping the TX crystal for a BRIEF test like he did as long as he made sure no other pilots were flying at the time. Improper crystals CAN (but not always) do strange things in the way of spurious signals. Swapping in a friends RX crystal and seeing if the friends TX could control the plane would be a valid test. (TX must be a compatible type of course).
I have no problem with him swapping the TX crystal for a BRIEF test like he did as long as he made sure no other pilots were flying at the time. Improper crystals CAN (but not always) do strange things in the way of spurious signals. Swapping in a friends RX crystal and seeing if the friends TX could control the plane would be a valid test. (TX must be a compatible type of course).
I was flying a new 50cc plane on a specific channel. It's third flight.
While flying low over the field I experienced a glitch, the engine cut out and the plane augured in HARD.
I went to talk to another person there who had co-incidentally turned his radio on at this time. He was NOT on my channel....
A few months went by...
This time I was flying a smaller EP aircraft.... same channel as before... same guy at the field...
I noticed that whenever it passed in front of his location while he was flying my plane would glitch....
I went over to talk to him
It turns out he had changed his TX crystal.
I pulled out my new frequency checker which dynamically displays over/undertones, interference, etc....
Sure enough, his TX was producing an overtone signal smack in the middle of the channel that I was using ( ch 45 ).
This is because he swapped the crystals and in so doing "detuned" his TX.
I told him he owes me at the least a new airframe, but he refuses to own up.
Fortunately he also doesn't show up anymore as well.
10-14-2008 | 11:25 AM
#17
RE: Crystals Failure?
ORIGINAL: opjose
Even a brief test is a no-no!!!!
I was flying a new 50cc plane on a specific channel. It's third flight.
While flying low over the field I experienced a glitch, the engine cut out and the plane augured in HARD.
I went to talk to another person there who had co-incidentally turned his radio on at this time. He was NOT on my channel....
A few months went by...
This time I was flying a smaller EP aircraft.... same channel as before... same guy at the field...
I noticed that whenever it passed in front of his location while he was flying my plane would glitch....
I went over to talk to him
It turns out he had changed his TX crystal.
I pulled out my new frequency checker which dynamically displays over/undertones, interference, etc....
Sure enough, his TX was producing an overtone signal smack in the middle of the channel that I was using ( ch 45 ).
This is because he swapped the crystals and in so doing "detuned" his TX.
I told him he owes me at the least a new airframe, but he refuses to own up.
Fortunately he also doesn't show up anymore as well.
ORIGINAL: bruce88123
I have no problem with him swapping the TX crystal for a BRIEF test like he did as long as he made sure no other pilots were flying at the time. Improper crystals CAN (but not always) do strange things in the way of spurious signals. Swapping in a friends RX crystal and seeing if the friends TX could control the plane would be a valid test. (TX must be a compatible type of course).
I have no problem with him swapping the TX crystal for a BRIEF test like he did as long as he made sure no other pilots were flying at the time. Improper crystals CAN (but not always) do strange things in the way of spurious signals. Swapping in a friends RX crystal and seeing if the friends TX could control the plane would be a valid test. (TX must be a compatible type of course).
I was flying a new 50cc plane on a specific channel. It's third flight.
While flying low over the field I experienced a glitch, the engine cut out and the plane augured in HARD.
I went to talk to another person there who had co-incidentally turned his radio on at this time. He was NOT on my channel....
A few months went by...
This time I was flying a smaller EP aircraft.... same channel as before... same guy at the field...
I noticed that whenever it passed in front of his location while he was flying my plane would glitch....
I went over to talk to him
It turns out he had changed his TX crystal.
I pulled out my new frequency checker which dynamically displays over/undertones, interference, etc....
Sure enough, his TX was producing an overtone signal smack in the middle of the channel that I was using ( ch 45 ).
This is because he swapped the crystals and in so doing "detuned" his TX.
I told him he owes me at the least a new airframe, but he refuses to own up.
Fortunately he also doesn't show up anymore as well.
10-14-2008 | 11:36 AM
#18
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From: Poolesville, MD
RE: Crystals Failure?
ORIGINAL: bruce88123
I did say "as long as he made sure no other pilots were flying at the time". Perhaps you missed that point. It is indeed an important one.
I did say "as long as he made sure no other pilots were flying at the time". Perhaps you missed that point. It is indeed an important one.
10-14-2008 | 03:02 PM
#19
RE: Crystals Failure?
One thing that I don't think was mentioned above (I might be wrong): There is no 100% sure way of knowing if a bad Rx crystal caused the crash. Although you can determine that the Rx crystal is NOW bad by swapping out another one on the same freq., it is possible it is NOW bad because you just ran the plane into a fence and damaged the crystal, not because it was bad before it crashed.
10-23-2008 | 09:51 AM
#20
RE: Crystals Failure?
These radios are sold worldwide and they aren't going to redesign their cases to sell just of the US.
10-23-2008 | 09:54 AM
#21
RE: Crystals Failure?
Should I assume that you are referring to the old "CB" type license that used to be required to operate an R/C TX?
10-23-2008 | 10:10 AM
#22
RE: Crystals Failure?
ORIGINAL: Sport_Pilot
No, there is no FCC licience to repair RC radios. There is nothing in the regs that require a licence, only Futaba and other demanding it is so. If you go back and reread the reg it says you cannot MODIFY the radio, it does not say you cannot service it. However it says NO ONE may modify the radio and that messing with the frequency so that it transmits on a non RC frequency is a modification. Therefore if you change the crystal you may be modifying the radio. Only someone with the proper frequency analyser and skill can do this and be sure he is not modifying the radio.
Should I assume that you are referring to the old "CB" type license that used to be required to operate an R/C TX?
"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.
This mean a LICENSE.
Changing the crystal IS an adjustment which may cause a need for FURTHER adjustments. It certainly causes a need for further testing to determine the status of operation.
10-23-2008 | 10:52 AM
#23
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From: Poolesville, MD
RE: Crystals Failure?
Not only that but changing a crystal without retuning the associated chokes, can cause serious sideband and overtone issues.
I've the recipient a radio hits caused by an idiot who elected to change his crystal, destroying my plane!
The guy erroneously assumed that he could merely swap out crystals...
I had a plane on a different frequency which had always been rock solid reliable.
I was making circuits of the airfield, and noticed a glitch as my plane went by his station.
I didn't think of it at the time... on the next pass my plane went in when it went by his station...
After the crash I pulled out a frequency checker I picked up that has an LCD display that shows overtones and spikes...
Sure enough his TX was producing a spike on my channel.
When the guy put his original crystal back in, the spikes disappeared on other channels.
I told him he owed me a new plane...
He never returned, never offered to pay, and is no longer a club member.... good riddance!
I've the recipient a radio hits caused by an idiot who elected to change his crystal, destroying my plane!
The guy erroneously assumed that he could merely swap out crystals...
I had a plane on a different frequency which had always been rock solid reliable.
I was making circuits of the airfield, and noticed a glitch as my plane went by his station.
I didn't think of it at the time... on the next pass my plane went in when it went by his station...
After the crash I pulled out a frequency checker I picked up that has an LCD display that shows overtones and spikes...
Sure enough his TX was producing a spike on my channel.
When the guy put his original crystal back in, the spikes disappeared on other channels.
I told him he owed me a new plane...
He never returned, never offered to pay, and is no longer a club member.... good riddance!
10-23-2008 | 03:00 PM
#25
RE: Crystals Failure?
ORIGINAL: bruce88123
Re-read post #3 above. You are absolutely in error.
"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.
This mean a LICENSE.
Changing the crystal IS an adjustment which may cause a need for FURTHER adjustments. It certainly causes a need for further testing to determine the status of operation.
ORIGINAL: Sport_Pilot
No, there is no FCC licience to repair RC radios. There is nothing in the regs that require a licence, only Futaba and other demanding it is so. If you go back and reread the reg it says you cannot MODIFY the radio, it does not say you cannot service it. However it says NO ONE may modify the radio and that messing with the frequency so that it transmits on a non RC frequency is a modification. Therefore if you change the crystal you may be modifying the radio. Only someone with the proper frequency analyser and skill can do this and be sure he is not modifying the radio.
Should I assume that you are referring to the old "CB" type license that used to be required to operate an R/C TX?
"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.
This mean a LICENSE.
Changing the crystal IS an adjustment which may cause a need for FURTHER adjustments. It certainly causes a need for further testing to determine the status of operation.
If there was a requirement for an FCC license then it would have said so. Instead it says <b>certified</b>. Read the parts about broadcast, aviation and others were a license is required. I think they have been using factory certification, not FCC license.
