rfxcasey

Hi, Ihave a XTM nitro x-cellerator that came with a Cirrus transmitter. I use new batteries in the transmitter but the range is very poor only about 100ft. One of the techs at my local RC shop said it probably needed the crystals replaced. Ihave been looking for the Cirrus 27Mhz FM crystal set and have only found number 2 which is something like 27.028Mhz or something. They make about 5 different crystal sets but there is only 1 or 2 online sources that carry them and they are always out of stock. Is there some other crystal I can use like Fatuba or whatever that will work in this controller. Iwould just like to avoid getting the exact same frequency crystal I already have just in case there is an interference problem in my neighborhood not to mention the RC shop is right down the road from me and they have a few tracks out there with people running cars and planes all the time so I would like to get a less common channel. I know the best thing to do would be to go 2.4Ghz but I don't wanna spend that kind of cash right now.

nitrosportsandrunner

any brands FM crystals will work in your remote. so, traxxas or some other brand that uses FM crystals will work fine.
you should be able to find pairs on ebay for around $10. i have a traxxas radio right now with propulse crystals in it, works great.
just as long as you get FM(not AM) crystals, they will work fine in your radio.

on a side note, i have never had crystals go bad.
does your Rx antenna have any damage?
have you checked to see if your crystals are firmly in their slots?
has your Rx ever gotten wet?
silly question here, but are your radio batteries good?(we all forget to check these sometimes)

mechanizeddeath

The crystals are more or less universal, so long as they're the same general band and modulation (27MHz FM in your case). I have a bunch of RTR 27MHz AM crystals from different brands and they all interchange flawlessly. Traxxas, Tower Hobbies, Tamiya, Kyosho.

Crystals are supposedly fragile, but I've never had any of them go bad. I left a few sets in the pocket of my hoodie, and they went through the washer AND dryer, yet still work. I'd be more inclined to suspect the transmitter itself, perhaps the antenna. Might want to make sure it's all the way in, I had range issues on my boat (almost lost it!) when I noticed the antenna was only screwed in by a single thread.

Argess

Crystals are like a lightbulb filament in that they are supported on two wires inside their metal case. They don't go bad, but an impact can break one of the little wires, so it's possible that they can act intermittently. They should not affect the range at all.

If there is excess receiver antenna wire, try getting a longer antenna tube and use more wire (I'm not familiar with your vehicle, but I assume it has an antenna tube). Make sure transmitter antenna is fully extended.

Antenna on vehicle is vertically poalrized (stands straight up), so make sure you hold your transmitter so its antenna is straight up as well.

Use fresh batteries. Investment in a good battery tester is a good idea.

I'm not familiar with your radio either, but most of them are basically the same. If you know an electronic technician, he may be able to improve the range by tuning the reciever front end to match the antenna (one adjustment, either a coil or a potentiometer located adjacent to where the antenna wire is soldered) and he can tune up the transmitter power (usually one adjustment, the 2nd coil back from the antenna, tyically labelled L4. The last coil L5 rarely needs adjustment, but it's the only other one he should touch). Advise him not to re-tune anything else on the circuit boards.

rfxcasey

My antenna is good as far as I know. It is brand new. The one that came with it fell apart. The transmitter has always been like this since I first got it. I read a post somewhere about adjusting the posts inside but I don't know how I could tell if it's tuned in except for trial and error. I put brand new energizers in it and it still had crappy range so for 10 buck I think the crystals are a fair gamble. At least I will have a second set and it will tell if the crystals were the problem or not. Any one know about adjusting the pots in the transmitter?

What about these http://www3.towerhobbies.com/cgi-bin...?&I=LXMZD8&P=7 do you think they will work?