Creating 10.7 MHz from other frequencies

[DMartens]

Hi ... I need to create a 10.7 MHz frequency to use with a TMS9918 ... this 10.7 MHz is triple the NTSC color carrier frequency of 3.574595 MHz.
I have crystals of 3.574595 MHz, also of 14.318180 MHz (4xNTSC) and also of 28.636360 MHz (8xNTSC).
I know using a PLL-type circuit with an appropriate divider-factor in the feedback loop would be able to achieve this.

Is there a way to generate 10.7 MHz from any of these above frequencies _without_ using a PLL?

[moffy]

Hi ... I need to create a 10.7 MHz frequency to use with a TMS9918 ... this 10.7 MHz is triple the NTSC color carrier frequency of 3.574595 MHz.
I have crystals of 3.574595 MHz, also of 14.318180 MHz (4xNTSC) and also of 28.636360 MHz (8xNTSC).
I know using a PLL-type circuit with an appropriate divider-factor in the feedback loop would be able to achieve this.

Is there a way to generate 10.7 MHz from any of these above frequencies _without_ using a PLL?

100% multiply the 3.574... by the 14.318... and bandpass filter at 10.7, but why instead of a PLL, I have no idea.

[CaptDon]

10.7 and 21.4 crystals are cheap and easy to obtain. Why not just order one? How do you get 10.7 by 'multiplying' the 3.57 by the 14.318???

[jzx]

You can do a 3.57 MHz oscillator, filter the 3rd harmonic and amplify. Search "overtone" oscillator o "frequency multiplier"

[David Hess]

You can do a 3.57 MHz oscillator, filter the 3rd harmonic and amplify. Search "overtone" oscillator o "frequency multiplier"

That is what I would do.  A tripler stage is trivial; implement a class-c amplifier stage and used a tuned filter on the output to recover the third harmonic.  A 3.57 MHz square wave from a fast logic gate could be used.

[wraper]

You can make 3.57 MHz crystal run on 3rd overtone. Just why not buy a correct part?

[mawyatt]

Could use the 3.57MHz crystal in an overdriven oscillator and then injection lock a 10.7MHz oscillator to the 3.57MHz crystal oscillator (3rd harmonic).

Best,

[PCB.Wiz]

Is there a way to generate 10.7 MHz from any of these above frequencies _without_ using a PLL?

Sure :
The modern way would be a Schmitt XOR gate, and simple third phase RC delays. Then (A XOR C) XOR B gives 3f  ( eg using SN74HCS86)

or, you can make a ringing circuit with an LC and moderate Q at 3f, with Schmitt follower, and kick it with a narrow impulse at f.
 
These give 3.574595 *3 = 10.723785 MHz