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Old 09-14-2004, 06:33 PM
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Location: Kingman, AZ
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Default RE: 72mhz AM tx with 75mhz crystal


i know it's not right...what i want to know is how does this set up work???i'm using it for small 1\8 & 1\2A two channel models...i have another radio for my big planes...if i buy a AM 72mhz rx and put a AM 75 mhz crystal in it will it work with the tx???

John I realize your frustration and understand you want to do it right. Unfortunately there is no easy answer and the answer to your question of how does it work has to be a guarded maybe, maybe not. First off there are a lot of wide band Futaba AM radios floating around out there that are not even legal anymore. Yes I realize AM's are still produced by all the majors that are narrow band but the problem is identifying what you got. I would go to the Faq on the Futaba website which does list the legal narrow band Futaba AM tx's model numbers. If your model # is not listed don,t waste any money on this radio it is time for retirement. OK another indicator but not neccessarily accurate way to tell if this is a wideband Tx,Rx is to look on the Rx and if it says it is Dual Conversion then the likelyhood is that at least the Rx is narrowband Yes I know that there are modern single conversion Rx's that are narrowband but in the case of older Futaba it is an indicator. Another indicator is if the Tx has a gold sticker on it somewhere, If so then your are probably OK.

OK all of the above is just the wide/narrow band problem but a far more devious one is the fact you do not know which Channel on 72 the tx was tuned to originally. By the way its likely that this is the reason that you lost that airplane in a crash more so than battery failure. Putting crystals of an entirely different band in, is most certainly going to result in a detuned Tx with an unknown loss of performance. Now if you know what channel the Tx was orginally on then you could install that crystal and you may be OK However if you put just any crystal in that is in the 72 band I would not fly that radio untill it was tuned for the channel that you changed to.

Only just my opinion. Swap meet Radios especially AM are frequently a bad investment if you don,t know exactly what you are looking at.