[time-nuts] Low phase noise VCO
lists at cq.nu
Wed Feb 10 01:41:26 UTC 2010
With most SDR's a spur on the clock creates a spur in the radio. No matter how you do your multiply, you will wind up with some sub-harmonics running around. Much better / easier / quicker to start at 64 or 65 MHz.
On Feb 9, 2010, at 8:32 PM, Bruce Griffiths wrote:
> Thats not very useful when you want the 4th harmonic as its amplitude is zero fro a 25% duty cycle.
> Using a duty cycle of 1/8, 3/8 or 5/8 will maximise the amplitude of the 4th harmonic.
> Max Robinson wrote:
>> If you start with a square wave odd order is all you can get but if you start with a pulse with a 25% duty cycle you can get even order. It's best to optimize the pulse width for the harmonic you want.
>> Max. K 4 O D S.
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>> ----- Original Message ----- From: "Nick Foster" <bistromat at hotmail.com>
>> To: <time-nuts at febo.com>
>> Sent: Tuesday, February 09, 2010 6:35 PM
>> Subject: Re: [time-nuts] Low phase noise VCO
>>>> From: bill at iaxs.net
>>>> To: time-nuts at febo.com
>>>> Date: Tue, 9 Feb 2010 18:24:39 -0600
>>>> Subject: Re: [time-nuts] Low phase noise VCO
>>>> Which leads me to ask a novice question:
>>>> Why not pull a 16 MHz crystal and multiply to 64 MHz?
>>>> If you count down from 64 to 10 MHz, isn't the multiplication inside the
>>>> Perhaps the noise is multiplied by 4, but would it work for the intended
>>>> Bill Hawkins
>>> Can you do x4 multipliers? I thought odd-order harmonics were usually used for multipliers. I'd be happy to be wrong!
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