[time-nuts] 100 MHz Source
Richard W. Solomon
w1ksz at earthlink.net
Wed Apr 30 10:54:33 EDT 2008
That seems to be the simplest, yet most effective way of doing what I need.
I'll try it.
Thanks for the help,
73, Dick, W1KSZ
>From: SAIDJACK at aol.com
>Sent: Apr 29, 2008 6:17 PM
>To: time-nuts at febo.com
>Subject: Re: [time-nuts] 100 MHz Source
>I think a very inexpensive and simple way to multiply the 10MHz to 100MHz is
>the following. It only uses three standard CMOS chips:
>Use a 100MHz VCXO to generate your output frequency. Digikey has one for
>$28: Digikey number 744-1213-ND. This part has about -160dBc/Hz noise floor,
>For the simple control logic:
>Use an NXP 74LVC163 counter with preload to divide 100MHz by 5 to get 20MHz.
>Use a 74LVC74 to get a 10MHz reference out of this 20MHz, with 50% duty
>Feed this 10MHz, and your 10MHz reference signal into an Exor gate
>(74LVC86). This is the phase comparator.
>Low-Pass filter the output of the Exor gate with a low pass filter that has
><1Hz bandwidth. Say 2.2K Ohms into 100uF Tantalum with 100nF cap in paralell,
>into another 2.2K Ohms/100uF Tantalum low pass filter. This signal drives the
> VCXO input.
>That's all folks.
>Should cost you less than $35 including shipping, and generate a very stable
>100MHz signal. Jitter, very low Phase Noise, etc determined by the 100MHz
>VCXO. ADEV determined almost entirely by the 10MHz reference source.
>In a message dated 4/29/2008 14:17:50 Pacific Daylight Time,
>mctylr at gmail.com writes:
>Run a 100 MHz oscillator in a divide by 10 PLL (Phase Locked Loop)
>configuration, compared to your 10 MHz standard? If the Motorola /
>Freescale MC145170 (-2) was still in production, that might be a good
>one to use. Maybe National LMK03002.
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