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rc frequencies vs crystal numbers

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Old 08-18-2003, 03:59 PM
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bucco
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Default rc frequencies vs crystal numbers

I am a bit of a newbee when it comes to the computer, anybody know a site that matches 72 75 frequencies with their crystal numbers as 72.160 is ? numbers crystal?
Thanks in advance
Dave
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Old 08-18-2003, 04:10 PM
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Default rc frequencies vs crystal numbers

AMA Website

http://www.modelaircraft.org/comp/frequency.htm

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Old 08-18-2003, 05:34 PM
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Default rc frequencies vs crystal numbers

Frequency to Channel #
1. Subtract 21 from the hundredths of the frequency (ex. 72.790: 79-21=58)
2. Divide by 2 (58/2=29)
3. Add 21 to get the channel # (29+21=50)


Channel # to Frequency
1. Subtract 21 from the channel # (50-21=29)
2. Multiply by 2 (29x2=58)
3. Add 21 to get the hundredths of the frequency (58+21=79, or 72.790)


Found on www.advancedrc.com
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Old 08-18-2003, 05:47 PM
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Default rc frequencies vs crystal numbers

Not sure what the real question is here since you indicate "72.160". That frequency is a pre-1991 wideband frequency no longer in use, nor authorized. Those frequencies were marked by colored flags, in this case, blue & white. It won't match up to any of today's crystals/channel numbers or authorized frequencies.
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Old 08-18-2003, 05:57 PM
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Default rc frequencies vs crystal numbers

Or you could just look in youyr AMA membership manual which list the channelization plan for all the hobby bands: 27, 50, 53, 72 and 75Mhz.

By the way 72.160 is not a legal frequency in the US and I beleive may be one of old channels obsoleted with the national freqency plan many years ago. There are currently industrial, commercial use of those old channels and it would be a big mistake to use it.

If that is one of your channels then that would mean that your radio is a wideband and also illegal to use.

Hope this is not the case.

John
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Old 08-19-2003, 04:00 AM
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bucco
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Default rc frequencies vs crystal numbers

Well, I told you I was a Newbee. The frequency I quoted was on the back of an old transmitter that was in an estate sale. I was hoping to use it for a little project but could not locate the proper crystal. Now I see why. This is the reason I posted the question and I want to thank all of your for your courteous replies to my obvious (to everyone else) ignorance. I learn some interesting facts every time I log into this site.
Thanks
Dave
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Old 08-21-2003, 05:44 PM
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Default rc frequencies vs crystal numbers

Re: rc frequencies vs crystal numbers
Before the 10 year phase in of the current numbered frequencies, there were only 6 frequencies available. Instead of putting channel numbers on our transmitters, we used colored flags on the antennas to indicate the frequency. A blue ribbon and white ribbon on the antenna together indicated 72.160. Purple & white was 72.320, red/white = 72.400, for instance. The white indicating 72 Mhz. Ham freqs were marked by a black flag with another color. 27 Mhz was only a single color flag per frequency. During the initial phase in, they tried to use the resistor color code for flags but eventually decided that channel numbers would work better like the CB system which was going strong then. The old 72 feqs went out of use around 1988. They now have pagers and industrial control systems (like for cranes) on them. Probably more info out there on RCU if you did a search.

Rick

Many thanks to THUD-DRIVER



quote:
--------------------------------------------------------------------------------

bucco wrote on 08-19-2003 9:21 PM:
When you write of color flags, what are you referencing?
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