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Another newbie crystal question.

Old 08-28-2003, 08:47 PM
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Pajo
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Default Another newbie crystal question.

Haven't even flown yet, but I have two JR Txs both 35mhz

an old JR Max with a 35.220 crystal
and a new JR 378 with a 34.950

What channels do the figures denote.

i.e is the first one channel 22 ???

and the second one channel 95 ??

and are they interchangeable.

I have already read that DIY changing Tx crystals is not allowed in the U.S. but its ok here in Ireland.
Old 08-28-2003, 09:23 PM
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HarryC
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Default Another newbie crystal question.

35.22 is channel 82, and 34.95 is channel 55.

They might be interchangeable, but a few years ago JR altered the basis of the underlying frequency of either their transmitter or receiver crystals but I can't recall which it was - so you have to be careful to get the current or the old style. If you swap crystals and they work then it is the correct style, though always do a range check as a matter of standard procedure anyway.

Harry
Old 08-28-2003, 09:43 PM
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Pajo
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Default Another newbie crystal question.

Thanks for that m8,
don't really need to know, but curious as to how the channel number is dedeuced from the numbers I gave, or is it just a table that states
x= channel y
Old 08-28-2003, 10:03 PM
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HarryC
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Default Another newbie crystal question.

There is a chart, www.bmfa.org/handbook/hbook_13.html

You can do it without the chart. Take the first two digits after the decimal point and add 60. Thus 35.000 is 00 + 60 = channel number 60. 35.010 is 01+ 60 = channel 61. 35.220 is 22 +60 = channel 82.

For frequencies starting with 34, the result of adding 60 is over 100 so remove the 100 from the answer. Thus 34.950 is 95 + 60 = 155, remove the 1 to get channel 55.

Harry
Old 08-28-2003, 10:40 PM
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Pajo
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Default Another newbie crystal question.

Thanks a lot m8,
very informative.

Cheers
Old 08-28-2003, 10:43 PM
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Pajo
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Default Another newbie crystal question.

Originally posted by HarryC
34.95 is channel 55.

Now I know why there were two stickers with 55 written on them in the Tx box Doh.

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