[time-nuts] oscillator choice question

Bob Camp lists at rtty.us
Sun May 2 00:23:22 UTC 2010


A lot depends on what sort of result you are looking for. 

If a simple calibration of the standard in your counter to +/- 1 ppb  is your goal, then a reasonable oscilloscope and some patience will get the job done with what you already have. 

If continuos lock to GPS at a 10X or 100X tighter level is the goal, it's tough to beat a Thunderbolt at around $100. 

Most modern gear is looking for a 10 MHz standard input. It's easier to start with 10 and divide for the item that wants 0.1, 1, or 5 MHz than to multiply up from something lower. I would limit my shopping list to OCXO's that already put out 10 MHz and have a voltage control input. There are usually a bunch of them being auctioned in the $50 range. If your accuracy requirement's aren't to tight, you can indeed use a TCXO. If you wait long enough, you probably can score a 10 MHz rubidium for $70 - they make fine GPSDO's ....

Regardless of the oscillator used, you will still need some sort of electronics in-between the Res-T and the oscillator. The complexity is up to you. A lot of what you are doing is the same weather you are running a TCXO or a Rb.

It all depends on you needs and your budget. 


On May 1, 2010, at 3:28 PM, chris at yipyap.com wrote:

> I'd like to build a GPS disciplined frequency standard.
> I am slowly gathering up pieces.
> I have a Trimble Resolution T GPS card that appears to work,
> and an antenna for it.
> I'm thinking now of the oscillator part.
> I have two Racal 1992 counters with the stable oscillator option (probably 04E since these are former military units).  I also have an old Schomandl  ND-100M Frequenzdecade signal source with an  (I assume) ovenized oscillator w/unknown properties.
> I'm wondering if I could use an oscillator from one of these
> gizmos instead of shelling out real money on ebay?  Speaking of
> which, it seems like half the people in China are selling oscillators.
> I assume some of them are good for this application and some not
> so good?  The usual suspects from HP and Agilent are there, and
> they seem to command a pretty good (high) price.  Which is why
> I'm eyeing the Schomandl.
> Chris
> w0ep
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