Radio control Transmitter and receiver for planes

[tytower]

I need some simple help please

I bought a 72 Mhz Low R/C transmitter to fly my plane but it came without a crystal so now I am trying to find out exactly which crystal RX and TX I need to order. The support from the supplier Tower Hobbies is hopeless and after 5 emails telling me about FCC regulations I have given up with them

I have an Electrify 4 channel FM 72MHz Low receiver also so I just need the right crystals or a matching set.
So I am planning on ordering a set on channel 38 . Is this the right thing to do. I am now of the opinion that the transmitter and the receiver need identical crystals but if that's the case why do they sell them separately as RX and TX crystals . Is there an offsett or something to worry about?

Please don't waste posts telling me about government regulations if you feel inclined as I am fully capable of assessing that situation myself being a full call radio amateur.

 

[jpanhalt]

There can be differences between manufacturers as to which crystals to use. I have heard, for example, that dual conversion and ABCX receivers use different crystals for the same channel.

The best policy is to get a set of crystals from the manufacturer of your radio. Note, some transmitter crystals are buried in an RF module that plugs into the back of the transmitter. Changing crystals on those modules might work, but I have never done that. I think it could be risky, as in my many years of RC, the only time I have had to have something retuned was an Airtronics transmitter with a module. They do drift, and when they do, as in my case, the modulation was screwed up. It is a simple tuning tweak, but not something you or I could do at home.

Considering what you are flying and the fact that you will not likely be at the extreme of range, I would get get a crystal set, plug them in, do a ground range check, and fly. There are many other sources for crystals than Tower.

John

 

[Sceadwian]

Typical RC aircraft radios have a simple easy access crystal port. And most receivers are dual conversion, verify your receiver type and as jpan said just pick up a set of 'standard' RC 72mhz crystals at the first place you can find that sellls them. Try to pick a channel that the trasmitter was actually tuned for, Low band typically means it was tuned for the center channel of the first half of the RC channel space and high band is center tuned for the center channel on the second half of the channel spacing so try to pick something as close to the center as you can. But if you know what crystal was last used in it try to get that one, as 'legally' you need to have the transmitter retuned when the crystals are changed and it has to be done by a technician. This is however being more than a little anal about the whole thing.

 

[HarveyH42]

There are a lot of transmitters types anymore, but doubt much difference in the crystals themselves, or frequency allocations. You need to buy 72 MHz crystals, and just make sure the Rx and Tx are of the same channel. They are sold separately, as the transmitters use to be quite expensive, so you wouldn't want to buy a separate transmitter for every plane you own. Planes are also pretty easy to lose or crash spectacularly, transmitter just needs one crystal. There are also usually at least one hobby shop nearby, they seem very eager, enthusiastic, and helpful. Crystal are small, and everyone needs one, usually several sets, so you don't interfere with other pilots.

 

[Sceadwian]

If Tower was giving you a hard time it was only over technicalities and they're just trying to protect themselves legally as they're a large online supplier. If the FCC had a full paper trail to prove that someone sold a crystal for install to 'joe public' there could be pretty hefty fines involved.