Rx/Tx Crystals

[Mack]

Is there a difference between the Rx and Tx crystal. I bought a new set and they are both Rx. I tried them out today and there was no communication between the radio and reciever. I don't know if the shop made a mistake by giving me two Rx crystals.

[chappers]

well as you just found out , yes there is a difference and no they wont work!

[Mack]

Thanks Chappers
It's back to the shop again!!

[G-DAVE]

Remember there is also FM and Duel Conversion Rx Xtals.
Dave

[Mack]

The only other two crystals I had was a Rx duel conversion and a FM Tx(also bought together at the shop)and they worked together. Can see why they should though, because if one side of a duel goes down it will still work and you wouldn't know the difference(so I am lead to believe)

[G-DAVE]

Mack I think you use Futaba radio then the Transmitter will always have a 35 mHz FM xtal , no matter what rx system you use.
If using a FM Receiver then a FM Rx xtal will be used
If using a duel conversion Rx wether it be a FM or PCM a Duel Conversion xtal will be used.
I'm not a electronic expert and there will be others much wiser, but duel conversion refers to the way the rx converts the signal from the TX -before telling the servos what to do- it converts the signal twice.
Something like that anyway.
Dave

[Mack]

Oh now I get it . Thanks Dave

[Raptorite]

Hi Mack,

Just incase you still aren't sure about these crystal thingies, there are different types for different functions, which must match the device they are being plugged into.

For example, a trnamitter has a specific crystal, which happens to be single conversion and is the only one that can be used in a transmitter.

A single conversion PPM receiver will always use a standard single conversion crystal and a Dual conversion PPM receiver will always use a Dual Conversion crystal. The only slight anomaly is that a dual conversion PCM receiver uses the same dual conversion crystal as the PPM receiver, as the modulation type is irrelevant.

Providing the crystal matches the device it is to be used in you should be OK.

I hope this helps.

Cheers,

Pete.

[Jamez]

OK but how

Right all you smarty pants's knowing all about crystals. My dragon fly has a PCM reciever and a 'lovely' Zen Hua radio which is also PCM, how the hell do I get my all in one board to pick up on a different transmitter even if it is on the same frequency......... the tx I want to use is a JR 642

[chappers]

is the JR transmitter capeable of PCM modulation?

[G-DAVE]

Check out your radio manual it will tell you if your Tx will do ppm and pcm :?: - if so just select pcm -Job done.
Dave

[Jamez]

PCM

ZPCM and SPCM, but we have tried it with a JR crystal in the tx, will I have to fit a JR crystal to the Rx as well?