Help me make a stable crystal based VCO

[ahmad_abdulghany]

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]

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]

Re: Crystal based VCO

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

 

[ahmad_abdulghany]

Re: Crystal based VCO

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

No, sorry, I'm interrested in wide band FM! then do you have another suggestion?
Thanks,
Ahmad,

 

[E-design]

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.