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HelicopterMain Discussion › working out crystal frequency
08-12-2007 10:32 PM  10 years agoPost 1
sirchunks29

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coventry west​midlands

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need help to work out frequency example 35.300 35.200

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08-12-2007 11:15 PM  10 years agoPost 2
arceye

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UK

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35.200 = channel 80
35.300 = channel 90
35.250 = channel 85
34.980 = channel 58

Just add .600 to the number after the . then use the FIRST 2 digits to get the channel number

34.980 + .600 = 35.580 now use only the first 2 digits after the . and you get 58 so that would be your channel
35.200 + .600 = 35.800 so the first 2 digits after the . are 80 giving the channel 80

that should be some help to you

Also Refer to the BMFA handbook Page 67 section 2 The 35MHz Band

Andy


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The Blingiest DOWNGRADE a Raptor can have

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08-13-2007 12:09 AM  10 years agoPost 3
AirWolfRC

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42½ N, 83½ W

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So what's the crystal frequency ?

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08-13-2007 09:34 PM  10 years agoPost 4
arceye

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UK

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Airwolf:

As far as I am aware the crystal frequency is the final output frequncy /4 .

In UK and on a JR system the crystal goes through 2 stages of doubing so for a given frequency of 35.200 the crystal frequency would be 8.8000 Mhz or there about.


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The Blingiest DOWNGRADE a Raptor can have

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08-13-2007 09:47 PM  10 years agoPost 5
AirWolfRC

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42½ N, 83½ W

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For Transmitters - most radio systems use a crystal frequency that is the same as the transmit frequency.

For Receivers - most single conversion units use a crystal frequency that is 455KHz below the operating frequency and most dual conversion units add another mixer that requires a crystal frequency 10.7MHz below the operating frequency.

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08-13-2007 10:05 PM  10 years agoPost 6
Andy from Sandy

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Bedfordshire, UK

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It is all in the BMFA manual. I assume you are a member for the insurance if nothing else.

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08-13-2007 10:08 PM  10 years agoPost 7
AirWolfRC

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42½ N, 83½ W

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Not having seen the manual, I'm in the US, are the actual crystal frequencies in the manual or just the channel number assignments for the various operating frequencies ?

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08-13-2007 10:51 PM  10 years agoPost 8
Andy from Sandy

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Bedfordshire, UK

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Here in the UK we work on the 35MHz band. The frequency range is 34.950 = channel 55 upto 35.300 = channel 90. Channel separation is 10Khz

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