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Help me make a stable crystal based VCO

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ahmad_abdulghany

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Hello all
I want to make a stable crystal based VCO or simply FM Tx (i.e. after adding AF and RF amps), Can anyone give help concerning that??
Thanks alot in advance,
Ahmad,
 

throwaway18

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Crystal based VCO

Read some books about radio circuits.

A crystal controlled VCO can only be varied in frequency by a small amount. Typically 1 part in 100000
For example a 10MHz crystal controlled VCO can typically only be pulled by +/- 1KHz

If you use low frequency crystal followed by frequency multipliers to make a VHF/UHF transmitter you can get enough frequency shift for narrow band FM.

You can't pull a crystal enough to make a good wide-FM transmitter for 88-108MHZ.
 

Borber

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Re: Crystal based VCO

If you are interested in NBFM you can use MC2833 with appropriate crystal.
 

E-design

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Re: Crystal based VCO

Look at www.rohm.com search for BH1417 very easy to use with simple dip switch.

I am attaching the detailed datasheet as I see they don't do that on their site anymore.
 

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