why is 72mhz not legal for surface vehicles like boats?

[robster94gt]

Hey all,

I was wondering why surface vehicles can only be operated on 75mhz, and not 72mhz. I've got an older 4 channel radio that I'd like to use in my sailboat, but I guess that's illegal. What would the penalties be for getting caught doing this and why?

Thanks alot,

Rob

[CG Bob]

The FCC giveth and the FCC can taketh away. Here is the FCC bandplan (http://wireless.fcc.gov/services/personal/radiocontrol/data/bandplan.html) for rado frequencies in the 72-75 MHz range.

Surface vehicles can also be operated on the 6 frequencies available in the 27 MHz range.

If you have an Amatuer Radio (Ham) license, you can operate any model craft in the 6 meter band range (50 MHz).

[patmat2350]

The penalties are not written anywhere, so that the jack-booted federal agents in black helicopters are free to do with you (and your model and your radio) as they please! :eek:

Also, you might try asking why over on the wingy-thing forum, I'm sure you'll get some excited answers! :eek: :eek: :eek:

Pat M

[robster94gt]

Guys,

I'll be operating in Canada, and in my particular city there are jack boots aplenty. Maybe not working for the gov., but definately those who like to call the police. I wouldn't really worry, but I might be sailing at a pond that a club uses. My concern is that someone who actually knows something frequencies will lecture me or worse.

Rob

[robster94gt]

Pat,

I'm sure I'd get lots preaching over in the planes - much along the lines of the dangers of lipo batteries.

[robster94gt]

Checked the FCC link. Still not sure why surface can't be run aircraft freq. and vice versa though.

Rob

[CG Bob]

The penalties are not written anywhere, so that the jack-booted federal agents in black helicopters are free to do with you (and your model and your radio) as they please!
Pat - WRONG - here's the penalties.

[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: 47CFR95.218]

[Page 538]

TITLE 47--TELECOMMUNICATION

CHAPTER I--FEDERAL COMMUNICATIONS
COMMISSION (CONTINUED)

PART 95_PERSONAL RADIO SERVICES--Table of Contents

Subpart C_Radio Control (R/C) Radio Service

Sec. 95.218 (R/C Rule 18) What are the penalties for violating these rules?

(a) If the FCC finds that you have willfully or repeatedly violated
the Communications Act or the FCC Rules, you may have to pay as much as
$10,000 for each violation, up to a total of $75,000. (See Section
503(b) of the Communications Act.)
(b) If the FCC finds that you have violated any section of the
Communications Act or the FCC Rules, you may be ordered to stop whatever
action caused the violation. (See section 312(b) of the Communications
Act.)
(c) If a federal court finds that you have willfully and knowingly
violated any FCC Rule, you may be fined up to $500 for each day you
committed the violation. (See section 502 of the Communications Act.)
(d) If a Federal court finds that you have willfully and knowingly
violated any provision of the Communications Act, you may be fined up to
$10,000, or you may be imprisoned for one year, or both. (See section
501 of the Communications Act.)

[48 FR 24890, June 3, 1983, as amended at 57 FR 40343, Sept. 3, 1992]

Here's a link to the FCC (http://www.access.gpo.gov/nara/cfr/waisidx_04/47cfr95_04.html) rules for personal radio, which includes R/C models. The R/C rules are sections 95.201 thru 95.401. R/C Rule 7 (Section 95.207) is titled "On what channel may I operate". I believe the Canadian rules are similar to those in the U.S.

[CG Bob]

Checked the FCC link. Still not sure why surface can't be run aircraft freq. and vice versa though. About 30 years ago we didn't have all these R/C model frequencies. Prior to 1990 or 91, there were a few shared frequencies in the 72-75 MHz band. There were some R/C car tracks and boat ponds near model airplane fields. Several model aircraft were "shot down" by people operating boats and cars. I think that there might have been lawsuits (or the threat of them) by people who got injured by the falling plane debris. The Academy of Model Aeronautics (AMA) got together with the boat and car sanctioning bodies and petioned the FCC to shift surface models to 75 MHz and aircraft to 72 MHz.

With the increase in electric fliers using the same city or county parks where you may be running a boat, it is safer to be on the correct frequency. Unfortunately, most of the RTF park fliers happen to be on 27 MHz, just like most of the RTR cars & boats.

[Kmot]

Point #1) That's what it's all about. Your old 72mhz radio signal can "potentially" travel over a mile to an airborne model and shoot it down. Airplane model is up high making line of sight range much further than surface vehicles.

My concern is that someone who actually knows something frequencies will lecture me or worse.


Point #2) You obviously know it is illegal, wrong, and morally corrupt to do so. And yet you are willing to proceed at the risk of endangering the use of r/c models of all types in your community if you cause an accident that harms a person or property.

[robster94gt]

kmot,

so If I was in the park flying my slowstick with my new 72mhz radio and shot down that airborne model that was over a mille away - that would be legal, right, and morally acceptable? My question is why does putting it in a boat make it illegal? I'm not seeing how it becomes dangerous.

Obviously I don't yet understand why it is dangerous to do so - so suggesting that I'm morally corrupt is a bit of a stretch and quite frankly an insult.

CG Bob - Thanks for the info regarding the origins of the seperation of two frequencies. Any thoughts as to why flying a park flyer would be less dangerous than sailing the boat with same radio on 72mhz?

Rob

[Davcruz]

I think that we have reached a new junture here in model R/Cing. There was a time not many years ago before the advent of these inexpesive EP park fliers where if you wanted to fly an R/C plane you went to an R/C field or to some desolute place away from everything else, there was really not much worry of another "legal" 72Mhz system being run on the same freq. as another already in use and close by.

That is different now, as newbies to the hobby buy these EP's and go to the park or school yard or wherever and fly them, not aware if there is an RC field nearby.

I don't know what will happen, but I see some change within the freq. layout as we have it now in the near future.

However, until then it is commonly known amoungst R/C hobbiest what freqs. are to be used for what type of R/C. I personally would not run a surface vehicle on an aircraft band no matter what, I don't think it is the right thing to do.

[viking57]

robster, Yes the chosen wording, I agree was a little misplaced , however what he was trying to impart to you is this without insult, lets say yours was a power boat that you spent many hours building and an airplane guy, running on a ground freq. caused you prized powerboat to run aground and splinter into pieces , or worse hit a specator. We in the rc hobbies need these rules to protect the SAFE pursuit of our chosen hobby , what ever that may be! it goes both ways you see? With out rules governing freq. we could quickly have chaos. So in short, to follow the rules as set forth by the fcc promotes the "rc" hobbies as a whole so we can all enjoy our chosen hobby safely.by the way I am a boat and car guy , and allways follow the freq. rules in order to preserve our hobby! peace brother, were all in this together! regards, John

[robster94gt]

Davcruz,

It's clear the landscape has changed. I understand how it is more likely to find interference due all the new rcers out there using their gear just about anywhere. just wondering why it would be so wrong to use an "aircraft" frequency on a "surface" vehicle. It's clear that it's illegal, and the two have distinct frequencies, but I'm not really seeing the danger, or "wrongness" of it.

Rob

[CG Bob]

CG Bob - Thanks for the info regarding the origins of the seperation of two frequencies. Any thoughts as to why flying a park flyer would be less just wondering why it would be so wrong to use an "aircraft" frequency on a "surface" vehicle. It's clear that it's illegal, and the two have distinct frequencies, but I'm not really seeing the danger, or "wrongness" of it.

You don't want to be held responsible for shooting down an airplane. You can ruin it for other r/c modelers in the area, by getting that location closed to all r/c models.

In the first post, you said you have an older 4 channel radio on a 72 MHz (aircraft) frequency, and you'd like to use it in a sailboat. First a little comparison of the control setup is needed.

On an airplane:left stick up/down = throttle; left stick left/right = rudder; right stick up/down = elevator; right stick left/right = aileron.
On a bost: left stick up/down = sails or throttle; left stick left/right = ?; right stick up/down = ?; right stick left/right = rudder.

Lets say that you and Mr. Airplane are in the same park, seperated by a large line of trees. You're operating your sailboat on 72 MHz. Mr. Airplane shows up, and is about 150 yards or meters from your location, he can't see you because of the trees. Mr. Airplane turns on his tx, then his rx and starts flying, but doesn't notice any glitches in his control - even though he is on the same 72 MHz freq as you. About three minutes into the flight, Mr. Airplane starts doing aileron induced barrel rolls and crashes into a family having a picnic. It was about this time that you decided to have your sailboat make a large gradual turn - your rudder command is now controling Mr. Airplanes ailerons. The airplane hits one of the children in the head, causing a large cut and a concusion. The airplane weighs 5 pounds, and was about 100 feet high before the crash. The family decides to sue Mr. Airplane for the damages. Mr. Airplane later finds out you were in the park that day, operating a sailboat on an aircraft freq, he decides to sue you. The city/county park administrators now post a sign at all of their the parks: NO RADIO CONTROL MODELS ALLOWED. Because of your actions, you are out several thousand dollars in court costs (maybe considering bankruptcy); and all of the r/c modelers have lost the use of a great facility in the area.

I happen to work in a hobby shop. The shop also sponsors a r/c car race series. Races are held in a large parking lot across the street from our shop. We get people coming in every day looking for help with their car, boat, or plabe. On race days, we don't turn on radios that are on 27 or 75 MHz, because we don't want to cause a wreck on the track.

In my boat club, I'm the director of the Scale section, we also have a very active Sailboat section. On our Scale days at the lake, I personally check all the transmitters, if a guy shows up with a radio on 72 MHz, he doesn't sail his boat. There are no R/C flying fields within 5 miles of our club pond.

[fhhuber506771]

kmot,

so If I was in the park flying my slowstick with my new 72mhz radio and shot down that airborne model that was over a mille away - that would be legal, right, and morally acceptable? My question is why does putting it in a boat make it illegal? I'm not seeing how it becomes dangerous.

Obviously I don't yet understand why it is dangerous to do so - so suggesting that I'm morally corrupt is a bit of a stretch and quite frankly an insult.

CG Bob - Thanks for the info regarding the origins of the seperation of two frequencies. Any thoughts as to why flying a park flyer would be less dangerous than sailing the boat with same radio on 72mhz?

Rob

There is already a large discussion of the problem caused by "park flyers" who operate aircraft on aircraft only bands in parks that are less than 3 miles from "established RC airfields". There is a potential danger of people as much as 5 miles away from each other on the same frequency creating interference for each other if conditions are "ideal" (usually they aren't and the 3 mile spacing is reasonably safe)

Currently the only way to reduce the danger of park flyers (small slow models operated in a park or other non-traditional location) "shooting down" thier big brothers is educating the parkie operators and getting thier cooperation in not using the parks which are edxcessively close to the estabished sites.

If the problem is exacerbated by people insisting on use of air frequencies to operate surface models... then the end result will be added legislation (more rules with more potential criminal penalties) which has so far been avoided. (because if you can keep the government's mitts out its usually a good thing.)

So, you have a choice:

1) Be part of the solution (prevention) and follow the rules plus look for the local regularly used sites to be sure you don't create an interference problem.

2) Go on and do as you please, potentially creating a fatal accident. (and maybe getting caught... causing a death while doing something illegal is a minimum of negligent homicide... see you in 30 years.)

Chances of doing more than just breaking some other guy's model aren't high... but there are cases of unexplained loss of control of model accidents which HAVE caused serious injuries. And a lot of clubs are now buying scanners which would give them the ability to track down the interference source.

My advice is... try to be part of the solution. Its not hard and its not really all that expensive to get the type radio appropriate for the model.

[robster94gt]

Guys,

These are all really good examples of the dangers of shooting down a plane with interference. CG Bob - In the case of Mr. airplane being shot down and crashing into the picnic and just about killing the child - would he not be able to sue me if I was using my radio with my parkflyer? Would the plane not get shot down if I was operating a boat?

fhhuber - You make some good points about safety that all parkflyers should follow - check if there is any flying going on in your area. However, again I'm not seeing how using the radio to run the boat instead of the plane is actually more dangerous. The potentially fatal accident scenario is there because of not checking for frequency conflicts in the area, not because of the vehicle. All I'm seeing is a legality/liability issue - not any actual difference in safety.

Rob

[robster94gt]

Would the plane not get shot down if I was operating a boat? -correction - change boat to plane

[afc]

Seems like you have all the facts and are looking for some justification for your actions. Well, A man is going to do what he intends; all I can say is be prepared to face the consequences of your actions.
:)

[CG Bob]

robster -

If you're operating a model on the same frequency at the same time as another model, and you cause the other model to lose control & crash - you are just as liable as the pilot of the other model - especially if it causes personal injury or property damage. It doesn't matter if the models are planes, boats or cars.

However, again I'm not seeing how using the radio to run the boat instead of the plane is actually more dangerous. The potentially fatal accident scenario is there because of not checking for frequency conflicts in the area, not because of the vehicle. All I'm seeing is a legality/liability issue - not any actual difference in safety. The reason for the aircraft/surface model frequency seperation is to avoid the potential for accidents; this is based on real experiences of R/C modelers getting hurt while pursuing the hobby. By your indiscriminate use of an aircraft frequency in a boat, YOU ARE the problem, and causing the rest of us to lose sites where we can operate our models. Legality/liability issues start because of an unSAFE act - mistake or accident - usually resulting in a disability or death. Because of these past mistakes and acccidents, the SAFE operator uses the correct frequency band for their model.

If you want to fly airplanes and run boats from the same transmitter/receiver frequency, you have the choice of operating on 27 MHz or getting your Ham radio license and operate on 50 Mhz.

27 MHz has 6 frequencies available for aircraft or surface models.
72 MHz has 50 frequencies for aircraft use only.
75 MHz has 30 frequencies for surface models only.
50 MHz (Ham bamnd) has 10 frequencies for surface or aircraft models.

[robster94gt]

I was looking at futaba attack radios on ebay. There was an Attack was listed, but it was listed as being 72mhz - I emailed the guy because that seemed strange. He said that the radio has a 72mhz crystal set in it, but it can be switched to 75mhz. Is this possible? I thought 72mhz radios were FM and 75mhz were AM. Can anybody shed some light on this?

Rob

[fhhuber506771]

There is a safety factor in just knowing that its illegal for someone with a boat to use the aircraft frequencies (and the ability to assume that the rule is obeyed..) A guy can go to the flying field having seen someone operating a boat 1/2 mile away and legitimately be able to believe the boat is NOT on the aircraft frequency so its safe to fly.

However if some idiot is out there running his boat with an aircraft frequency... and the guy starts up his plane and starts flying then the boat guy's radio causes loss of control from his illegal and moronic action... I would hope the boat guy got the maximum punishments under the law because he deserves it.

************

You can NOT change that 72 mhz Futaba to 75 mhz without factory service that costs more than the radio is worth

[RGinCanada]

Robster,
I am on a tight modelling budget, and I have to justify my expenses. ;) Even with limited funds, I'd buy a new radio over used. Do you need 4 channels for your sailboat? I've picked up a few 2 channel AM radios for $30.00 from Tower. They also have a nice Futaba 4 channel FM surface radio for under $150.00.

Once you've bought it, and start using it, the pain of the $150.00 will be long forgotten. You'll have a warranty, and resale value on these radios is high, so if you get bored, your investment isn't trash.

You'll spend more than $150.00 on batteries, paint, glue, balsa and hard liquor on a single model. My $0.02!

I'll let the dust settle on air/surface frequency discussion.

[robster94gt]

RG - Thanks for your view on the new/used radio issue thing. I'll keep that in mind and probably spring for the new unit. I'll eventually get around to buying a nice 4 channel unit so I can put a nice sound module on a little graupner Lotse I've been waiting to finish forever.

I just checked out the site for an Ottawa boat club. Looking forward to getting back home checking out the pond.

Oh by the way, thanks for posting with message that wasn't overflowing with hostility and and veiled and not so veiled insults, eh?

Rob

[Umi_Ryuzuki]

I was looking at futaba attack radios on ebay. There was an Attack was listed, but it was listed as being 72mhz - I emailed the guy because that seemed strange. He said that the radio has a 72mhz crystal set in it, but it can be switched to 75mhz. Is this possible? I thought 72mhz radios were FM and 75mhz were AM. Can anybody shed some light on this?

Rob

You can not just switch crystals from 72mhz to 75mhz. The Crystals only change the "Channel" within the Frequency. And there are 30 channels per Frequency. The channels can be changed by switching crystals, but to change the Frequency, the transmitter needs to be retuned using an occiliscope.

[robster94gt]

Umi,

Thanks for the info - I didn't think that it was possible. The guy on ebay has actually changed the listing to say that it operates on both 72 and 75. Hope nobody buys it on that basis.

Rob

[RGinCanada]

Robster,

Its all good, eh :D

I think the only way you'd get a more passionate response to a post would be to launch a discussion something like this:

A homeowner uses his handgun to shoot down an R/C B-52 powered by 8 Wren turbines, being flown on surface frequency. The airplane crashes in a residential yard, startling a pitbull that subsequently bites the mailman. Would public or private healthcare treat the injury better?

:P

[robster94gt]

robster, Yes the chosen wording, I agree was a little misplaced , however what he was trying to impart to you is this without insult, lets say yours was a power boat that you spent many hours building and an airplane guy, running on a ground freq. caused you prized powerboat to run aground and splinter into pieces , or worse hit a specator. We in the rc hobbies need these rules to protect the SAFE pursuit of our chosen hobby , what ever that may be! it goes both ways you see? With out rules governing freq. we could quickly have chaos. So in short, to follow the rules as set forth by the fcc promotes the "rc" hobbies as a whole so we can all enjoy our chosen hobby safely.by the way I am a boat and car guy , and allways follow the freq. rules in order to preserve our hobby! peace brother, were all in this together! regards, John

Hey John,

Never noticed that you posted that way back. I'm a plane/boat/car guy myself. Thanks for the sane and calm post :) You and my fellow Canuck on here making feel less like an immoral potential murderer with a total lack of regard for human life and a desire to throw the r/c world in chaos. Anyone who is isn't afraid to say peace brother is aces with me. :D Where's the love? It's right here man. Hey where's the peace sign emoticon?

Rob

[CG Bob]

I was looking at futaba attack radios on ebay. There was an Attack was listed, but it was listed as being 72mhz - I emailed the guy because that seemed strange. He said that the radio has a 72mhz crystal set in it, but it can be switched to 75mhz. Is this possible? I thought 72mhz radios were FM and 75mhz were AM. Can anybody shed some light on this You can get AM and FM radios on 27 MHz, 72 MHz, and 75 MHz. To further complicate life, 72 MHz is divided into Low (channels 11-35) and High (channels 36-60) bands. Changing frequencies between bands (27, 72 low, 72 high, & 75) requires the radio to be retuned by a factory authorized service center. Changing frequencies within a band is done by changing crystals, rf modules, or dialing in the new frequency (for synthesized units). Most radio manufacturers don't recomend changing crystals because it apparently violates the FCC regs in the US: apparently crystals do not meet the exact or perfect definition of a plug in module.

CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION
PART 95 PERSONAL RADIO SERVICES--Table 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.)

Sec. 95.209 (R/C Rule 9) What equipment may I use at my R/C station?
(a) Your R/C station may transmit only with:
(1) An FCC certificated R/C transmitter (certificated means the FCC
has determined that certain radio equipment is capable of meeting
recommended standards for operation); or
(2) A non-certificated R/C transmitter on Channels 26.995-27.255 MHz
if it complies with the technical standards (see part 95, subpart E).
(3) Use of a transmitter outside of the band 26.955-27.255 MHz which
is not certificated voids your authority to operate the station. Use of
a transmitter in the band 26.995-27.255 MHz which does not comply with
the technical standards voids your authority to operate the station.
(b) You may examine a list of certificated transmitters at any FCC
field office.
(c) Your R/C station may transmit with a transmitter assembled from
a kit.
(d) You must not make, or have made, any internal modification to a
certificated transmitter. (See R/C Rule 22.) Any internal modification
to a certificated transmitter cancels the certification, and use of such
a transmitter voids your authority to operate the station.

[robster94gt]

I had read that it was illegal to change freq. crystals on transmitters. It this a law that is adhered to at clubs?

Rob

[Umi_Ryuzuki]

I had read that it was illegal to change freq. crystals on transmitters. It this a law that is adhered to at clubs?

Rob

Yes, we adhere to this. The transmitters are taken to an authorized factory service man. (he has an occiliscope... ;) )

[patmat2350]

OK, so how thin is the ice under a user of an MCD Switch 8 unit?

- Pat M, who thinks his Switch 8 is pretty cool...

[Umi_Ryuzuki]

OK, so how thin is the ice under a user of an MCD Switch 8 unit?

- Pat M, who thinks his Switch 8 is pretty cool...


The MCD switch breaks down the the bandwidth allocated to that single servo or channel to a finer graduated waveform. But the switch does not and can not modulate any of the allocated channels of an existing reciever or transmitter beyond the existing specifications.

[viking57]

rob, no sweat friend,I truly dont think anybody meant any harm , we are all just passonate about the hobby.I personally did not read into your post that you ever intended to knowingly do wrong, only that an rc "brother' (tryin to squeeze an already hard to justify budget as we all must) needed to know why. So I felt a just response was in good order. rock on!! p.s.and you started an informative thread so your thrashing was'nt for nuthin!!lol :D take care!! John

[fhhuber506771]

You can not just switch crystals from 72mhz to 75mhz. The Crystals only change the "Channel" within the Frequency. And there are 30 channels per Frequency. The channels can be changed by switching crystals, but to change the Frequency, the transmitter needs to be retuned using an occiliscope.


Sort of half-right... each crystal retunes the FREQUENCY within the BAND. There are 50 frequencies for RC Aircraft use in the 72 mhz band and 30 in the 75 mhz band for "surface" use (cars and boats share with subs and hovercraft)

If you look at the "channel" label on a typical Transmitter it will say the "channel" number and below it is the frequency such as "Channel" 50 is 72.790 mhz and "channel" 54 is 72.870 mhz. (I just read those off of 2 TX's I have beside me, I didn't memorize the list.)

The FCC's "Channel" number system has led some people to the misconception that its all one frequency of 72 mhz... when it was intended as just a simplification. Well, the simplification of the reference numbers worked, but it makes the explaination of the system repeatedly necessary. (so it half worked.. like most of government programs.)

*******

There's some soldering work involved in changing the transmitter from 72 mhz to 75 mhz. Just using a 'scope and tweaking won't get you there.

[CG Bob]

I had read that it was illegal to change freq. crystals on transmitters. It this a law that is adhered to at clubs? That depends on the club, and if it's a contest day. Some clubs and event organizers will let you change crystals; others won't.

[fhhuber506771]

The law is vague about the requirements for changing transmitter crystals. (now) They rewrote it slightly something like 4 years ago.

Now.. instead of an FCC licenced tech being required to change the crystal... you just need someone competent to do a proper frequency verification. (with no definition of the competency requirements...) Obviously.. you can't competently check the frequency alignment without the correct scope/meter though.

********

In my opinion, any AMA Contest Director who knowingly allows transmitter crystal changes at the field durring his/her event should be reported to the AMA for revocation of his/her CD status.

Changing TX crystals has the risk of interfering with the neighboring frequencies. The risk is fairly low now (better crystal manufacturing tollerances) but it still exists. This risk is soething I find unaceptable to tollerate. (because it is SO SIMPLE to eliminate)

********

Some radio manufacturers are making it hard to get the transmitter crystals in the US to discourage swapping by people that don't have the proper test equipment. Some will sell the TX crystals to anyone that wants them.

*******

If you want the ability to use all 50 Air frequencies, or all 30 surface frequencies (or both) then i recommend the synthesized frequency capable transmitters. Pull the module, turn a switch and you have a new frequency. Its cheaper than buying all the crystals. (MUCH cheaper than buying the multiple modules)

********

Change the RX crystals all you want, any way you want... the primary risk there is to your own model.

Generally, a ground range check (tx antenna collapsed) will find any seriously reduced reception range, so its easy to be safe enough with the RX crystal change.

A ground range check will NOT tell you if you are "bleeding" into an adjacent frequency with the transmitter.

[robster94gt]

rob, no sweat friend,I truly dont think anybody meant any harm , we are all just passonate about the hobby.I personally did not read into your post that you ever intended to knowingly do wrong, only that an rc "brother' (tryin to squeeze an already hard to justify budget as we all must) needed to know why. So I felt a just response was in good order. rock on!! p.s.and you started an informative thread so your thrashing was'nt for nuthin!!lol :D take care!! John


Does an R/C enthusiast getting any cooler than this? I think not - Viking 57, you rock. Thanks for actually reading what I wrote, and not reading into it.

Anyway, this changing crystal thing is interesting. Now please don't read too much into this - I'm just asking- I was looking at the old transmitter of destruction and noticed something that even I wouldn't would risk doing. The freq. of the old radio is 74.400 - one of the banned channels for the old days. So from what I'm reading there's no safe way to salvage this radio (for use in a slock in an isolated area in Taiwan with no other flyers or family picnics even close) by changing the crystal to another freq. on 72mhz? I read something about "wide band". Does this actually pertain to the transmitter itself? i.e. - radios that were made when 74.400 was legal are wideband and there for banned?

Rob

[CG Bob]

The freq. of the old radio is 74.400 - one of the banned channels for the old days. So from what I'm reading there's no safe way to salvage this radio (for use in a slock in an isolated area in Taiwan with no other flyers or family picnics even close) by changing the crystal to another freq. on 72mhz? I read something about "wide band". Does this actually pertain to the transmitter itself? i.e. - radios that were made when 74.400 was legal are wideband and there for banned? You can contact the radio manufacturer and see if they will retune it to the narrowband specs which came into effect in 1990 or 91. The manufacturer may not support a radio that old, and you may have to buy a new one. Prior to the specs changing in 1990, we had less than 1/2 of the frequencies we have now. The radio frequencies were generally spaced more than 40 kHz apart; 74.400; 74.460; etc. To increase the number of available frequencies, the bandwidth between frequencies was made naroower, to 20 kHz; 75.41; 75.43; etc. The older wideband radios could and did cause interference on the neighboring narrowband freqs. There was a phase in period of several years for all the narrowband systems. In 1990, you could only get the "even" channel frequencies: 58 (72.950 MHz); 60 (72.990 mHz); 62 (75.410 MHz); 64 (75.450 MHz). Within a few years, maybe 3, we were able to get radio systems on the new "odd" channels: 57 (72.930 MHz); 59 (72.970 MHz); 63 (75.430 MHz); 65 (75.470 MHz).

[robster94gt]

So the radio itself is "wideband". Well, it can't be worth the retuning. It doesn't even have servo reversing. Besides it's a Kyosho - don't know who'd do the modification to it. If you want to change crystals in a radio, do they have to be the same brand as the radio?

[CG Bob]

If you want to change crystals in a radio, do they have to be the same brand as the radio? The crystals should be the same brand as the radio.

Referring back to FCC R/C Rule 22:
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.

Some people interpret (2) to mean a frequency module that plugs into the radio; others interpret "plug-in modules" to include crystals. You have a Kyosho radio, installing Futaba, Airtronics, or any other brand of crystals would be against the regulation; since the radio was certified for the brand of crystal in it.

[fhhuber506771]

The FCC rules (if you read just a little more than you posted) say that crystals ARE NOT modules. So there is no room for that interpretation to stand.

The module has to have ability to be fine tuned to correct for the crystal not being exactly on frequency.

Lets say a crystal is cut for 72.870... and its just 0.1% off.. 72.080 X 0.001 = 0.72080 add or subtract the intended withthe error.. Look up which channel you have. (because it isn't channel 54 any more)

The accuracy of the machines cutting the crystals is MUCH better than 1%... but the thicknesses being cut are so tiny there's no way to get the accuracy needed to ensure just swapping crystals is accurate enough.

********

An added reason for not using a different maker's crystal... the crystals are not really cut to the frequency of the radio signal.. they are cut to a harmonic of it... there is a frequency multiplier circuit in the TX and one in the RX. It is documented that Hitec uses a different multiplier than Futaba. If you (for example... I don't know the multiplier values actually used...) stick in a 4X multiplier crystal into a 6X multiplyer radio.. you are nowhere NEAR the intended frequency.

[robster94gt]

I was at the LHS here in Taiwan and found a Futaba Attack (2r? 2er?) with receiver and 2 servos for the equiv. of $60 CDN or $48.00 US, all taxes included. The only problem is that it's on 27mhz. I think I'd prefer the 75mhz route. Do any of you use 27mhz, or do you try to avoid it.
Judging from the prices I'm seeing I might as well just by the radio when I get home to Canada since there is no savings and I'll get 75mhz- I found a Hitec Ranger for only $40 US on Horizon, 50 shipped. Goofy looking radio though.

How difficult is it to make the left stick non-springy with the "ractchet" action?

Rob

[CG Bob]

How difficult is it to make the left stick non-springy with the "ractchet" action? It's a simple job, that takes about 15 minutes. You need the ratchet piece, ratchet screw, needle nose pliers and a philips scfew driver. Remove the 4 screws holding the trans,mitter halves together. Remove the spring from the stick; you may also have to remove the hook piece the spring attaches to. Install the ratchet with the screw. Test operate the stick. Replace the back cover, and install the 4 screws. The parts cost about $2.00. I've also made the ratchet piece out of brass stock.

[cshelden]

I can show a pic if needed but if you are in the "we tight club" aka good at scrounging. I've been using those plastic zip ties. Take a piece and cut it about 1" long or so, drill a small hole in it and attach the "ribbed" side towards the other ribbed side on the stick. Works great, not to mention cheap.

Charlie
OKC, OK
Member in good standing of the OKC "we tight club"

[robster94gt]

Charlie,

That's pretty clever.

Rob