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gravely_todd
03-13-2014, 12:19 PM
I have an older Futaba 6 channel FM radio with 72Mhz (plane/helicopter) frequency crystals in it. Can I just buy a set of 75Mhz crystals in whatever channel I want for surface and it will be ok and work correctly ? The receiver is dual conversion, so I would buy the appropriate dc crystals for both the tx and rx.

I know.....get rid of the old FM stuff and go with 2.4GHz....... I would do that, but have a perfectly functioning FM system I would like to use for my next build.

Does it even matter anymore if I were to leave it 72Mhz....and just not go close to any model airplane fields.... lol..


Todd

flatdeck
03-13-2014, 03:50 PM
Todd I do not think that the crystals are interchangeable. I would just keep the old radio..

Wayne

kaptain Jack
03-13-2014, 08:18 PM
You are right, no one flies FM anymore, its like leaded gas.

CG Bob
03-14-2014, 11:07 PM
Depending on the age of the radio, Futaba may be able to retune it for 75 MHz crystals.

2.4 GHz isn't for every model. I have 6 working r/c submarines. 1 is on 75 MHz and the other 5 are on 50 MHz. 2.4 only penetrates water a very short distance, something like 1/4".

modelman
03-16-2014, 01:30 PM
gravely todd-no you cannot put 75 MHz crystals in that radio but you can put in 27mhz crystals then you would be on a legal ground freq. I don't think it would do any harm to use the 72mhz but technically it is not legal. I have some 27mhz crystals I will give you if you want them. If interested pm me your address.

CG Bob
03-16-2014, 11:26 PM
The 27 MHz crystals won't work in a 72 or 75 MHz radio. The best bet would be to have the radio retuned and use 75 MHz crystals. Some info from the Futaba website (generally applies to other radio makers as well):

How do I change the frequency on my receiver?

Futaba 72MHz receivers are all center tuned within 1/2 or the other 1/2 of the frequency band. So, if you have a receiver on any channel within 11-35 (72.010 through 72.490), you can purchase a receiver crystal and change it to any other channel within 11-35. If you have a receiver on any channel within 36-60 (72.510 through 72.990), you can change the crystal and use it on any other channel within 38-60. However, ALWAYS perform a full range check prior to utilizing the equipment. If you have any doubts about its performance, it is always best to send it for service and let us match your transmitter (if your Tx has a module, only that needs to be sent) and receiver for maximum performance

Futaba 27MHz, 50MHz, and 75MHz are all center tuned to that particular band. Therefore, any 27MHz receiver on any channel can be changed to any other channel WITHIN THE 27MHz band, and same is true of 50 and 75 MHz bands.

For info on changing to another FREQUENCY BAND (ie. changing a 72MHz receiver to 75MHz), please click "Changing bands" (http://www.futaba-rc.com/faq/faq-6xsuper-q54.html)

modelman
03-17-2014, 03:16 PM
gravely todd-sorry, I was wrong about this. I must have been thinking something else. They WILL NOT interchange.

gravely_todd
03-17-2014, 08:55 PM
Thanks guys for all the information. I will look over the Futaba link and see how cost effective it is to be legal.....

Todd

Animal
03-23-2014, 06:43 PM
You could convert your radio to 2.4, I did it to an old Futaba Conquest using a Corona 2.4Ghz DIY Module with the help from Scott at SS-Tronix. You could also try the AnyLink2 2.4GHz Universal Radio Adapter, but you'll need a 2.4 receiver.

Pete