Changing Tx crystals

Although I'm sure someone will tell you it's technically illegal to change your own TX crystal unless you're a licensed technician, it's done all the time. Theoretically, with narrow band/dual conversion, you can change any frequency to any other within the same band. However, practically, I wouldn't go farther away than 3-4 channels unless I had it retuned. So, 36 to 42 will probably be ok. Dr.1 Driver "There's a Hun in the sun!"

There has been alot of controversy here regarding crystal changes. Even the legality has been debated. From a radio frequency perspective, the crystal controls the operating frequency. There are some slight variations in the precise frequency that each crystal will oscillate at, that still falls within the acceptable tolerance. Even changing a crystal with the same exact channel crystal will result in a slight variation. Is the variation enough to worry about? Well it just depends. Some transmitters can in fact be aligned to adjust for variation in crystals. Some dont have any adjustable components, primarily the single conversion and lightweight circuitry. The length of the antenna wire is also important and if not of proper length will result in less range.

My advice - Change the crystal. If you were going from one end of the band, say channel 12 to 59 my advice would be to have it realigned (tuned). When you are done, perform a range check and if it works OK, FLY AWAY.

Conventional wisdom is plus or minus 4 channels: okay. More than that, send it in for calibration. I have no personal information that would argue against this. Otherwise, a range check, done properly, is your best friend.

LOL :)

Hope that was just a Freudian slip.

Brian

-- Brian Cullen - (Leccyflyer) - Moderator

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Lets say you change the crystal and all is good for your setup as far as range checking ad you go ahead and fly. Someone out at your field is flying his $5000 giant scale plan on an adjacent frequency to the one you just changed to. He flys by your transmitter and S-P-L-A-T! Later, it is determined that your crystal change was just far enough off center to cause the radio interference to cause the demise of this plane. Are you prepared to reimburse the gentleman whos plane you destroyed by changing crystals? If not, have a trained technicion do it for you. It is a little cost for a lot of insurance that you won't damage someone elses planes. By the way, this is a true story. Thank god it wasn't my plane!

Moot

Hi Went to see a "Radio" guy to change crystals in my Tx n Rx..Went from 36 too 42.. He put the Tx on a scope and said it did not need to be retuned.. Went fly this past Sunday, no problem for me or my fellow flyers??