can anyone tell me if i can change a rx crystal from channel 31 to a 38 and have it work ok with my
futaba tx radio??
thanks for the help

no you cannot. 31 is low band and 38 is high band.

What transmitter / Reciever do you have?

The newer Futaba recievers are not band sensitive, let us know what model you have.

It doesn't matter what transmitter.

It does matter what RX though.

I just changed (reversed) my two Hitec RX crystals. One going to my Laser 4 (ch54) and the other going to my Focus (ch30). The Micro O5S single conversion receiver I switched from ch54 to ch30, and the Mini 6S single conversion receiver was switched from ch30 to ch54, and they both work perfectly fine after the switch. Will this last or should they be switched back?

The ch30 crystals say 72.390TF while the ch54 crystals say 72.870TF. Is this minor difference of concern to me in regards to reversing the RXs?

Glad I came across this thread, it will tell me whether I need to switch them back or not, even though they appear to work with the switch.

Tigerdude,
This thread really doesn't apply to your situation because the original post deals with Futaba receivers. On older Futaba receivers they are tuned for use in two bands that split the channels in half, a low band and a high band. If a low band crystal is put in a high band receiver, or vice versa, the receiver will not operate as it should and could cause a loss of the plane.

In your situation you will be fine. Hitec receivers aren't banded like Futabas are.

Ken

The Futaba's will also APPEAR to work properly but performance MAY suffer.

From Futaba's FAQ page:

Please explain Hi and Low band to me? I am not sure what the difference is between them.
Most of our 72MHz receivers are now tuned to the center of either a low band frequency (channel 11 to channel 35) or high band (channel 36 to channel 60).

By tuning to each band, you can easily and safely change your receiver crystal to anywhere within this high or low band range, without having to send it in to be retuned.

If you have a receiver that is not marked as to which channel it is, or if it is not marked with a sticker that says if it is High or Low, you can check inside the crystal slot to see if there is a red mark. If there is a red mark, this indicates that the receiver is High band.

The original poster never said he had a Futaba receiver, only that he had a Futaba transmitter.

I did not know at the time that Hitec was different, thank you for answering that ken. But I do know that Futaba has a low-and-high-band situation as I own two Futaba TXs that share same frequencies with different planes (gotta make sure one is off while flying the other, was cheaper to get flight-packs for the TXs I already have so had to get same frequencies) but back to the issue here.

I only purchase high frequencies from Futaba, but assuming hsink has a Futaba RX, low and high frequencies can not be switched. I don't know about Futabas and other RXs but this is the fact with Futaba radio systems, and as bruce says even if they appear to work they will not in the long run and will cause a crash eventually.

In, (hopeully), less than a year, after all of the 'me too' stuff is finished in the industry regarding 2.4; we will likely never have to have this discussion again.

It is my sincere hope that 72 MHz will just go away, and we will all be shoot-down resistant. With regard to 'diminished performance', there is really no such thing. These are crystal based radios, a technology from the early '30's. Either they will pass a range-check or they won't. Interference is not usually detected in a standard range test. It is therefore, a risk we must accept.

I am convinced that MOST incidents that are blamed on 'radio failure' are simply 'operator error'. I have seen a few too many people thumb-in a plane they were barely qualified to fly and then blame the radio. I have had 3 incidences of being 'shot-down' in my first 14 months of flying RC. In every instance, someone mistakenly turned-on. I never lost a plane, thankfully. I'm sure this is due to an abnormally sudden and swift barrage of explitives and threats which allowed the offending user to quickly turn-off.

I will be flying on 72 for one more year, (funny I should say that since I have only been flying for 16 months now). I will be experimenting with a new technology which I have been watching for almost a year on glow planes and foam. When there is a clear winner, I will gladly sell all of my crystals and rx's for pennies on the dollar and use the new technology in my more expensive planes.

As a relatively new flyer, I am quite surprised that it has taken this long for an industry/hobby wide upgrade in our most basic technological need.

I have several RX crystals, a few tuned modules and a synth module because I can't be bothered with sharing a frequency with someone who could potentially cost me more than he could afford to replace. I have never had a radio issue beyond the occasional momentary glitch in well over 250 hours of TX time. I do, however, follow the manufacturers guidelines regarding compatability and range testing....well, I only range test if I have changed something material to the radio gear...but still.

If you can wait for a decent 2.4 system to emerge in the industry, do so.

Now that is some fine advice. I am complete agreement and just hope we are 12 months from a clearer 2.4 landscape. Unfortunately, I think the timing is more like 24 months or more before the cost of equipment becomes tolerable. I suppose if I had worries about sharing frequencies with people who tended to ignore basic R/C transmitter etiquette, then I'd be more eager to pay "early adopter" prices.

Not likely,
72Mhz is just not going to go away overnight. Many new fliers will be buying used equipment while many older flyers, like myself,will see absolutely no reason to change considering the fact that I have numerous models flying on 72Mhz with no problems.

There are lots of "decent" 2.4 offerings on the market. In fact, they are well above "decent." They all work as they should, so do not sit around waiting for something "decent" to come out--you are wasting time. Now, if you are waiting for something bigger--then yes, you'll have to wait. JR has 9 and 12 channnel offerings coming out this summer. That should suffice anyone for a very long time. I'm sure futaba is right behind them--if you are a brand name guy. All the stuff out there now works. The only two valid reasons for waiting, as I see it, are A)--for more channels to be offered (which should be this summer) and B)--for the price to drop some (or to save enough money to buy one). Other than that.....

2slow,
I'm just finishing up doing a review on the JR X9303 9 channel 2.4 radio. All I can say is, WOW!!!! What a radio.

Ken

I'm upset with Ken. He won't even let me drool on it.

Bruce,
Trust me, I've done enough drooling on it for both of us!!!!

Ken

Like me--and can I tag on another question: I have a Futaba SKYSPORT 4VF on channel 36. I bought a used plane that already has JR servos installed. If I buy a JR receiver with a channel 36 crystal, should I be able to use my Futaba TX?

IF you buy a JR RX like this one
http://www.horizonhobby.com/Products...rodID=JSP30600
which can have it's shift selected to either positive or negative you will be fine.

You can also plug your JR servos into a Futaba RX with no problem, in case you were unaware of that.

The manufacturers have made it pretty easy on us to do just about anything we want.

That will be one nice radio. Seven channels is all I need, so I'll probably never own one (unless they come down about 300 bucks on price!) For me, the DX 7 is an awesome radio as well!

THANK YOU. Exactly the one I was looking at.