[time-nuts] WWVB D-PSK document

Bob Camp lists at rtty.us
Sun Mar 31 19:05:27 EDT 2013


Hi

If the VCXO's tuning voltage runs from zero to 5 volts, and the VCXO tunes 0.1 Hz / 0.5 volts at 12 MHz, then it has a total range of about 1 Hz at 12 MHz. That's about 0.08 ppm of tune range. A generic crystal likely has a tempo of 0.1 to 1 ppm / C. My guess is that you will need a bit more tuning range on the VCXO to keep things locked long term. Putting your tuning cap in series with the varicap should help this a bit. You may also need to add a coil in series with the crystal. 

Bob

On Mar 31, 2013, at 6:30 PM, paul swed <paulswedb at gmail.com> wrote:

> Thanks John.
> 
> 
> On Sun, Mar 31, 2013 at 5:21 PM, John Ackermann <jra at febo.com> wrote:
> 
>> At Paul's request, I've put his document about the PSK scrubber for WWVB
>> at:
>> 
>> http://www.febo.com/pages/**wwvb_psk/WWVB%20d-psk-r%**2003302013.pdf<http://www.febo.com/pages/wwvb_psk/WWVB%20d-psk-r%2003302013.pdf>
>> 
>> John
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