[time-nuts] WWVB d-psk-r update. Seems a reasonable solution

Bob Camp lists at rtty.us
Sat Mar 30 11:12:37 EDT 2013


I think it's pretty safe to say that the Vectron part mentioned is a VCXO with a crystal as the resonator. Indeed a ceramic resonator or an L/C resonator part would have a bit more drift and lower Q than a crystal based part. I would not try something like this with anything other than a crystal based part. At least as far as the commonly available stuff goes. I'm sure you could make it work with a hydrogen maser as the frequency source and a bit of DDS magic...

On Mar 30, 2013, at 10:23 AM, Jim Lux <jimlux at earthlink.net> wrote:

> On 3/29/13 9:01 AM, Bob Camp wrote:
>> Hi
>> Too much tuning range is easy enough to fix. Use a pot to set it on frequency and then hook it to the rest of the "stuff" with a fixed resistor. The gotcha would be if the poor thing drifts so much that it *needs* the wide range to stay in lock.
>> My guess is that you could buy a hundred VCXO's at auction for less than the cost of trying a dozen samples.
> wide tuning range VCOs have lower Q resonators, so the "outside the loop BW" noise will tend to be worse.
> The other problem I have found is that wide tuning range VCOs tend to drift more (that is, with a constant input voltage, their frequency changes more as they warm up or otherwise change temperature).
> It's a matter of sitting with the online order site open in one window, and the Vectron or whoever website open to their catalog in another and going back and forth comparing part #s..
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