I AM HAVING A PROBLEM WITH MY RADIO EQUIPMENT I HAVE A FUTABA FP-7UAP 7CH,PCM RADIO ON CH 38 AND I JUST BOUGHT A STANDARD FM RECEIVER I BOUGHT A CH 38 FM CRYSTAL FOR IT AND WHEN I TURN ON TRANSMITTER ALL I GET IS A TWITCH OF MOVEMENT ON THE SERVOS!! OK IM RUNNING THE RADIO ON PPM WHICH IS FM AND MY RECEIVER IS FM SOME ONE TOLD ME THAT IT MIGHT BE IN THE CRYSTAL IS THIS TRUE THE CRYSTAL IN MY MODULE IS A DIFFERENT COLOR THAN THE DUAL CONVERSION ONE IN THE RECEIVER AND ON THE BACKS OF THE CRYSTALS ONE SAYS "TYPE72-7 AND THE OTHER SAYS 72-10 IM NOT SURE WHAT THIS IS OR IF IT MAKES ANY DIFFERENCE AT ALL CAN SOME ONE PLEASE HELP ME????

make sure the TX is in "PPM" mode when using the "standard" RX. If the TX is in PCM mode it simply won't be understood by the RX.

Press the first 2 of the 6 buttons in a row simultaneously.

pres the 2nd button a couple of times to get to the parameters screen.

Press the 3rd or 4th button a couple of times to get it to be sayng "MODE F" or "MODE P" (I bet it says P at this point)

Press the 5th or 6th button to set it to "MODE F"

Press both the 1st and 2nd button at the same time.

Now the display will be flashing "PPM" in a box. Turn the TX off and back on.

Should work with the standard FM RX now. (and won't work with the PCM RX)

I have a Futaba Super 7. Its a GREAT radio. Simply outstanding for its age.

IT IS ON PPM MODE LIKE YOU SAID BUT SOME ONE AT OUR LOCAL HOBBY SHOP TOLD ME THAT SINCE THE RADIO IS A PCM THAT THE CRYSTAL IN THE MODULE WOULD ONLY WORK ON PCM RECEIVERS AND I MIGHT HAVE TO PUT A REGULAR DUAL CONVERSION CRYSTAL IN THE MODULE TO MAKE IT WORK? IS THIS TRUE? LIKE I SAID BEFORE ON ONE SIDE OF THE CRYSTAL IT HAS A (TYPE 72-7) AND THE OTHER SAYS (TYPE 72-10) DOES THIS MATTER ARE BOTH YOUR CRYSTALS READING THE SAME #? THANKS FOR YOU TIME AND HELP!! RICHARD JAMES

Where are you changing crystals? in the RX or the TX module?

You can not legally change crystals in the TX module.

The TX modules DO use different crystals from the ones used in TX's that don't have the modules.

The same module that fits a Futaba FG series FM radio (which is not PCM capable) fits my Futaba Super-7 which is PCM. PCM or PPM has nothing to do with RF tuning.

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Still interpreting your posts...


Which reciever did you buy? (Make and model number) Which crystal are you sticking in? (list the make and model RX it was pulled from.)

THE RECEIVER IS A STOCK FUTABA FP-R127DF DUAL CONVERSION FM AND THE CRYSTAL IS A D-CONVERSION 72.550 CH 38,THE MODULE IS A FP-TP-FM 72.550 CH38,WOULD THE SERVOS EVEN TWITCH WHEN I TURN ON THE RADIO IF THE CRYSTALS OR MODULE WERE BAD?

Sounding like you have a bad crystal somewhere... The servos will twitch as you turn on the RX no matter the condition of the crystal. The TX's RF board is de-energised in certain sections wen the TX crystal is pulled... and so is the RX board when you pull its crystal... but the servo positioning section will "blip" even without a crystal.

The servos should twitch a little even with the TX off. They should jump again when the TX is turned on, then go to the stick positions. This isnot the ideal way to turn on... but it checks if the RX is getting any signal at all They COULD jump even if the crystal is bad.... and then not go to the stick position because the bad crystal will not allow it to decode the positions info.

The 127DF RX SHOULD work fine with the 7UAP That's the type RX I use with mine. (well... one of 4 types...) the same RX with the same crystal works fine with another Futaba TX (cheap 4-channel) on the same frequency. (I tend to buy my radios on just one frequency when I buy new)

The TX module is the correct one, and might be the original that shipped with the TX.

All of my PPM Futaba crystals are type 72-10

My PCM RX's crystal does not list a type... and looks like its the original for the RX (I bought the system used and don't know if its the original RX)

The type number appears to refer to the crystal's intended useage.... the band is the first 2 digits.. then the other number seems to refer to the radios it will work in. Color seems to be linked to the series code... but that's not clear from what I can find.

http://www.futaba-rc.com/radioaccys/futl20.html

I have not and will not open the TX module to look at the crystal type number.

There is a chance you are trying a TX crystal in the RX... and that is not supposed to work... The TX crystal should say "TX" on the tag though.

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There is also the possiblity you are putting a high band crystal in a low band RX... this could drive the tuning off enough that resuslts can be unpredictable.

Look in the RX right beside the crystal socket. there should be a dot near the socket if it is high band. (visible without removing the plastic case if you are careful and have good light.) the dots in my RX's are red... I have read that some have white dots.

Ch 36 or higher is high band. Ch 35 or lower is low band.

ALSO... Futaba made some 127DF RX's that were tuned to 50 mhz (ham band channels 01 to 09) and some tuned to 75 mhz (surface use RC... no airplanes 62 to 90) and some on 35 mhz (for other countries... could be more too... I don't know all the bands used in other countries) and none of those will work correctly with a 72 mhz crystal.

This radio may only work on PCM. If that is the case PPM will never work. Both PPm and PCM transmit on FM so the crystal makes no difference.Call Futaba and talk the one of the radio techs. Dennis

WELL IT IS A HIGH BAND IT DOES HAVE THE DOT !HOW DO YOU DETERMINE IF YOUR RECEIVER IS A 50MHZ OR 72 IT VERY WELL COULD BE A 50 COULDN'T IT? I BOUGHT IT ON EBAY IT WAS NEW BUT NO PACKAGE THE THING THAT IS MAKING ME WONDER IS THE CRYSTAL IN THE MODULE IS GOLD AND LOOKS NOTHING LIKE THE NEW ONE DOES AND IT SAYS TYPE 72-7 I WISH I KNEW WHAT THAT MEANT. THANKS FOR ALL YOUR HELP

THE ONLY THING THAT MAKES ME WONDER IS THAT THE CRYSTAL IN THE MODULE IS GOLD LOOKING AND READS TYPE 72-7 AND THE ONE IN MY RECEIVER SAYS TYPE 72-10 I GUESS I NEED TO DO A PROCESS OF ELIMINATION.THANKS

Assuming the crystal in the TX is the original... the Super-7 SHOULD work with the 127DF RX using the 72-10 crystal if the crystals, TX and RX are all good.

Something is broken.

first try the RX crystal in a different RX.

Then try to operate the RX with a different TX.

Then if the problem has not been identified I'd be boxing it up and sending it to Radio South. It'd probably be a $60 repair bill (might be mre... might be less... never much less [&:]) but it would be RIGHT.