[time-nuts] [qs1r] Looking for good, cheap, external reference

Bob Camp lists at rtty.us
Wed Sep 22 10:53:08 UTC 2010


Hi

Are you interested in 24 hour stability or something longer than that?

Bob


On Sep 22, 2010, at 1:42 AM, Lester Veenstra wrote:

> 
> 
> 
> 
> From: qs1r at yahoogroups.com [mailto:qs1r at yahoogroups.com] On Behalf Of David
> Sent: Tuesday, September 21, 2010 10:55 PM
> To: qs1r at yahoogroups.com
> Subject: [qs1r] Looking for good, cheap, external reference
> 
> 
> 
> 
> 
> Hi,
> 
> I'm interested in doing some ionospheric research, but I don't want to break
> the bank with an $8,000 USD GPS disciplined Rubidium clock.
> 
> Anyone have some ideas on cheaper alternatives? The QS1R, and the Flex-3000,
> both use a TCXO and they have pretty good long-term stability, but there is
> a 1-2 Hz wander at 10 MHz imposed on the frequency over a duration of about
> 45 minutes to one hour. It looks like an exponential rise to one limit,
> followed by an exponential decay to the opposite limit. 
> 
> For long term stability, it obviously requires a temperature stabilized
> environment, but I have observed a slow diurnal variation in the TCXO mean
> frequency of about 1-2 Hz at 10 MHz just sitting on my desk, exposed in the
> morning to some brief sunlight.
> 
> For comparison, my old Icom 756ProIII looks astonishingly stable, but with a
> fixed frequency offset of around 0.8 Hz (the best I could do by tweaking the
> pot on the PLL). At most I see a very slow diurnal wander of around 0.5 Hz
> at 10 MHz. Whatever Icom did, they did it very well.
> 
> - de N7AIG
> 
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