patternfly

I can't believe this! I always thought you could not use Hitec crystals in futaba receivers, well today by mistake I've installed CH13 Hitec crystal in my Futaba PCM receiver and to my amazement it worked!!! I've range checked it and it seems just fine. Is this normal? I thought this was a no no and would never work.

JWN

My Feedback: (42)

A crystal is a crystal is a crystal. The radio manufs would like you to believe differently because they test with their cystals and can stand behind them. If you use someone else's crystal, they cannot guarantee the results. Want to know a secret? The radio manuf's don't make their own crystals. In fact, they don't make any of their electronic components. They purchase these parts from other companies and assemble them to the specifications of their product.

John

ChuckAuger

My Feedback: (12)

Hitec crystals won't work in a JR RX, and vice versa..I ran into a frequency conflict once and a guy loaned me some Hitec crystals..no go in the JR RX..luckily he had some spare JR crystals.

SO crystals may just be crystals, but they won't all just interchange.....the Hitec RX was a 555 FM, the Jr RX was a 226 FM

JWN

My Feedback: (42)

Hmmm, interesting. I had heard differently, but since I'm not into swapping crystals, had never tried.

Thanks for the clarification.

John

ChuckAuger

My Feedback: (12)

I had never tried it either. What's more, I have a fairly small amount of either Hitec and JR equipment and it all came to play at the same time. Even the guy who loaned me the crystals wasn't sure what would happen.

Also I have a lot of Futaba RX's and have never tried to swap any other brand crystals...I also have a lot of Futaba crystals...(My Hitec RX's are JR compatible..) so I'm not sure what else will or won't work, just my very limited experience with the Hitec/JR thing..

JWN

My Feedback: (42)

I knew the Futaba/Hitec swap would work from my experiences working in a hobby shop. Guys would come in all the time and buy Hitec crystals for their Futaba RXs because they were a couple of $'s cheaper. I always figured that if one worked one way, they all would. I wonder if it's the positive/negative shift that makes the difference?

John

JohnW

My Feedback: (6)

There are some other threads on matters similar to this concerning Synth modules. In short, you should NOT mix TX components made for two different brand radios... even if it seems like it works. Without lab testing for power, band, spikes, etc you have no idea what nasties you may be transmitting at the same time. Range checking IS NOT a suitable test for determining the purity of the transmitted signal. Until the manufacturer says you can use Brand X parts in their transmitter, just don't do it. I and my plane thank you.

patternfly

MonkeyBoy, we're talking about reveiver crystals not transmitter, therefore I'm not transmitting any "nastys" and am not a danger to your plane..

ChuckAuger

My Feedback: (12)

I did change the TX crystal in my JR TX module...with another JR crystal. No nasties...they had a computerized freq monitoring system on hand, that's what alerted me to the fact I couldn't fly on the original frequency I had brought. This was at a combat meet and we were flying 8~10 planes in the air at once, so I kinda figger I wasn't shooting anybody down (Flying against Monkey Boy's buddy Neal et al!!!)

ec121k

On the receiver crystals with non-compatibility. Were both receivers dual conversion? Some HiTec and some JR receivers are only single conversion. If youi took a crystal from, say a dual conversion receiver and installed it in a single conversion, it wouldn't work since the crystal frequency (not the channel frequency) are different. It's just the nature of the beasts. Nothing good or bad per say.

MikeL

My Feedback: (3)

The problem is the intermediary frequency in the dual-conversion systems. Different brands use different intermediary frequencies. Hitec and Futaba seem to use the same. It's not a matter of the transmitter's being positive or negative shift.