Rx and TX crystals + FS8 COPILOT. need Help
 

Hi,
I have just purchased a second hand FS8 copilot receiver that comes with with all the addons and an FM crystal with the numbers 35.120 / 45.820. I also have a Futaba 6EXAP 6 channel transmitter (second hand also) ,transmitting on 35,40,41, or 72 MHz . As I have no crystal with the TX Do I need one that will match the FM crystal that goes with the copilot. I am at a complete loss with the crystal matching. My other RC helicopters /planes have their own TX & RX complete with crystals so have had no problem in the past.. Just with Mixing a FUTABA TX with FS8 copilot RX.
Thanks in Advance, Ian ;)

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Your Futaba should have come with a crystal already installed in it AT THE FACTORY ( not at your LHS or by your vendor ).

The transmitter electronics were originally tuned to work with the crystal that came installed on the transmitter.

If you use a different frequency crystal, not only will your TX produce LESS power, but some of the signals will bleed over onto other channels.

This is why the FCC prohibits people from changing their own TX crystals. Changing TX crystals MUST ONLY BE DONE AT THE FACTORY or by a FACTORY QUALIFIED TECHNICIAN who will retune the electronics.

You could send your TX to Hobbico and have them install the crystal you want and retune the TX... but there will be a minor charge for this.

DO NOT swap in another crystal unless you KNOW it is on the same frequency that was originally installed on the TX.

-

You CAN however change the RX crystals at will... the only plane you may shoot down this way, will be your own.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

I,ve been using these new type rx from hobby city (carona) no cystal req for rx just lock it in as you do with a 2.4 and thats it ..its also very easy to switch between freq just put new crystal in tx then lock you rx in ..as the advert says crysatls are 50,60 70 technolgy but one thing I would do is package receiver in foam //have a look at them on there web page

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Not only is this very poor advice, but it is also illegal in many parts of the world.

For the very reasons I gave above YOU CANNOT simply switch TX crystals.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

catstrayuk,

Since your laws regarding swapping crystals in a transmitter may be different in the UK, I suggest you seek out a source at a local club to help you with this. They'll have the knowledge and know the British laws concerning crystal swapping.

Hogflyer

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

If anything Britain and the whole EU are a bit more stringent about this.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Pretty sure its legal in most countries, that is why the crystal is removable. Supposedly they are glued in the US radios, but the manufactures, and the FCC apparently do not care.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Actually that is incorrect.

The FCC cares very much about this.

And if that were not reason alone not to do it, there is the whole issue with the circuitry tuning, inter frequency leakage and reduced power when a user changes their own crystal.

It is irresponsible to suggest that people change their own TX crystals.

Pre-tuned modules are a completely different matter, as are PLL synthesized TX's or modules.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Hi , Purchasing the Futaba and FS8 seems to have caused quite a stir, sorry Guys , all I needed to know was should I get a futaba crystal ( which are removable ) that matches my TX frequency and another for the FS8 (that Matches the TX crystal to go in the FS8 Copilot)
Ian

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

As long as you do NOT change TX crystals you are fine.

You can change the receiver and co-pilot crystals to match the existing TX frequency without a problem.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

ok. Thanks For the Advise,
Ian :D

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Actually, the US is pretty much the only country that does have a restriction about changing out the transmitter crystal. Most other countries are fine with allowing the end users to change out the crystal. As was said above, this is why in most radios the crystals are readily accessable so that changing them out can be quick and easy.

The reason why the US is so strict about it is because of the very narrow allocation of frequencies for use by RC. The frequency allocations in the US has other uses in very close proximity to the RC ranges on the radio spectrum. The need to have a professional change the crystal and retune the radio is to prevent the radio from bleeding over to other uses such as commecial television. In most other countries they are allocated a large band of frequency for RC, and each channel is wider than what we us in the US, and this is why most countries have less channels to use than we do for RC.

Ken</p>

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Because you obtained the TX second hand, it is very important that you have either the original crystals installed, or replacement crystals of the same frequency.

Often the original frequencies are marked on the TX ( not the crystal frequency itself! ).

Make sure that this is the case or contact the original seller to find the frequency the TX came tuned for.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

right here we go again I run a Futaba 40mhz (allowable in NZ) I,m on 40.850 now others in our club can be on say 40.830 or 40.870 etc etc now if the retailer sells us radio,s and they are all set on 40.850 do we not end up with conjection on that freq and others cant fly until freq returned what we do is change crytals until we get evenly spaced out across the spectrum,,some clubs will arrange a swap on crystels evenotherwise we will have 15 people all sitting around with fingers up there...... waiting for a go so I put it to the above guy hes talking through a bloody great hole in his head thats why hobby shops sell crystall s and also that they are removable what happens if you buy a rx with no crystel does that mean you cant use rx cause thats what you are saying

[edited to remove derogatory comment. CGr Beginners Moderator]

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Then why did they approve so many radios with crystals removable from the front? When have they procecuted anyone? Why is the regulation unclear? I do agree the radio should be checked. It rarely requires tuning BTW.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Actually that is also a problem.  There are small varances between even crystals of the same frequency that can put a radio out of tune.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Actually Ken that is not correct.

See: [link=http://www.fai.org/aeromodelling/system/files/frequencies_GBR.pdf]Click me![/link]

The EU and other countries have gone to MORE RESTRICTIVE frequency regulations than ours.

Additionally they also more highly restrict the power output as well which is why we can run 400mw and while there are restrictions in place down to 10mw in some countries.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Hobby shops sell the crytals because the regulations leave it up to the end users to adhere to the regulations.

Here in the U.S. I can walk into any LHS and purchase a TX crystal, but Ken will be the very first to tell you that it is ILLEGAL to swap frequencies yourself...

Having been bitten by people like you swapping out crystals in their ignorance and having lost a plane to such idiots, I have first hand experience with the results of the tuning problems caused by crystal swaps.

The UK and EU are no different in this regard and have more prohibitive rules in most cases. You may want to do a bit of reading up on it.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Actually they don't.

Try to find one sold in the U.S. with an FCC sticker on it, or where the vendor can produce any form of FCC certification and permissions.

All of the big vendors have gone to pre-tuned modules, or PLL systems to eliminate the need for tuning, where frequency changing on the TX is permitted.

e.g. Hitec, JR, Futaba, even Corona, etc. have purposely eliminated the Crystal plug-in sockets to keep the FCC off their tails.


Sadly many Chinese vendors, of particularly low end TX's still have the crystal sockets which leads people to believe that it's OK to change them out.


Eh no.

Unless the TX uses synthesis, tuning is pretty much required.

I have one of those frequency checkers where you can actually see the results of crystal changes.

Unless the circuitry is retuned or adjusted, you get a substantial power loss at the center frequency because a portion of the signal is going out on adjoining "spikes".

Such spikes occur off channel and can kill reception on other frequencies as happened to me when someone showed up one day with a radio they had "adjusted" themself.


Here is a quote from Futaba's own web site on this subject:

How do I change the frequency of my transmitter?

For a module unit: to change the frequency you simply remove the module and replace it with a module on the new channel. You can even change 'bands' (IE 72MHz to 75MHz). All radio frequency circuitry is in the module so there is no need to 'retune' after a module change. (However, the receiver cannot be similarly changed to change bands. If you go to a new band you MUST buy a new receiver on that band. Please see the note below regarding crystal changes, which is valid for ANY receiver where you are changing within one frequency band.) DO NOT attempt to change transmitter frequency by changing the crystal within the module. You must use a module which is properly tuned to the frequency desired.

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.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Right. And this is even worst when crystals from another vendor are swapped in, even if it is on the same frequency.

Oh the JOYS of 2.4gHz, where we no longer have to worry or deal with all of this stuff.

The upgrade has not been cheap for me though... 9 down over 22 more to go!

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Jose,<div> ok, I've read the document you supplied three times now but nowhere on it does it say that the end user cannot change out the crystal in their transmitter. It does speak about them going to more narrow frequencies, but it doesn't say anything about the end user not being able to make the switch themselves. </div><div>
</div><div>I know a guy from England who is in the hobby and is well versed of the rules and regs both here in the US and in the UK  and I just got off the phone with him. His answer was indeed it is allowed in the UK to change out the crystals in the transmitter and it's actually a quite common practice to do so over there. In fact, he stated that he was absolutely shocked when he got to the US and found it was illegal to do so here in the US.</div><div>
</div><div>Ken</div>

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

I think Ripmax is the UK distributor and service center for Futaba
http://www.ripmax.com
You can contact them to find out what you can and cannot do regarding transmitter crystals. If you do need to send the transmitter in, they can give you the info you need and the price for the service.


The FMA receiver "should" be compatible with the Futaba transmitter. There are a few exceptions though.

From http://www.fmadirect.com/faqs.htm?category=49

Will FMA receiver(s) work with my o.e.m. transmitter?
With rare exceptions, FMA Direct receivers are available to be compatible with any transmitter manufactured over the past 25 or so years. The specific exceptions are one each model transmitter manufactured by Futaba, Airtronics, and JR when they first introduced the so-called PCM encoding format in the early 1980s. Those three transmitters can not be switched to PPM. You must confirm that your PCM transmitter has the capability to be switched or programmed for PPM encoding.



Will a Futaba, JR, or Airtronics crystal work in my FMA receiver?
No. The only crystals that work in FMA receivers are FMA crystals with the following exceptions:
Dual conversion crystals from Hitec and DAD will work in FMA dual conversion receivers; i.e., Interceptor, micro 2000, Fortress series, Quantum series, and Magnum series.

Carrell

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

That document references the applicable U.K. ruling documents on radio regulations that unfortunately address this in more technical terms.

Aside from all of that, the same problems exist with their bands vis-a-vis crystal changes affecting sideband spikes, power output, bleed, etc.

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Hi again,
I checked the Transmitter , the box and the frequency is 35mhz channel 79. I also looked at the frequency sheet that was in the box from which I presume the crystal is a 35.190 . the crystal that came with the FMA copilot has two lots of numbers. 35.120 and 45.820.
according to the frequency sheet 35.120 is channel 72. so all I need to get is the matching crystal from futaba. the transmitter is also switchable from PCM to PPM , All this is quite confusing so lay it on me in laymans terms
Ian

RE: Rx and TX crystals + FS8 COPILOT. need Help
 

Which is why I said "Why did they". ButOpps, seems they still make radios with removable crystals.

http://www3.towerhobbies.com/cgi-bin...NZB9**&amp;P=0