[time-nuts] Mini-time lab cost and maintenance

Charles Steinmetz csteinmetz at yandex.com
Fri Apr 10 14:23:38 EDT 2015

Adam wrote (via tvb):

>I was thinking maybe something with an uncertainty of around 1e-9 or 
>1e-10. Are there simple quarts oscillators that are good enough for 
>that or is more equipment necessary?

Adam, your original post seemed to state a goal of having a "small 
and lower level time lab."  Is a precision oscillator all you were 
thinking of (this would be sufficient to keep other clocked 
instruments, receivers, transmitters, and what not close to on 
frequency), or do you also want to do precision comparisons between 
the oscillator's output and other time and frequency signals, or 
precision time interval measurements, or to characterize the 
stability of other frequency sources to that level of precision?  In 
any of the latter cases, you also need precision counter/timers, and 
depending on the particular task you may need signal conditioners, 
mixers, filters, and other paraphernalia (some of which you may need 
to build yourself).

And as Tom pointed out, to be confident that your e-10 oscillator has 
not drifted beyond e-10, you will need some means of periodically 
comparing it to a better standard (which could be GPS or WWV, or a 
better local standard such as a cesium or hydrogen maser 
source).  This will require some additional equipment (alternatively, 
you could send the oscillator away for calibration periodically).

So, even with the clarification you sent to Tom, it is hard to advise 
you because you still haven't said what you are hoping to be able to 
do with your time lab.  I would venture to say that at a minimum, you 
will need a precision oscillator and a counter/timer with more than 
ten digits of resolution.  The counter/timers that come to my mind 
for a value-based home lab are the HP5345A, HP5370A or B, and the SRS 
SR620.  The 5345 is very capable but is often overlooked by 
time-nuts, and probably offers the best value available -- but you 
need to wait 1000 seconds to get its maximum resolution.  (There are 
others, but these three are, IMO, the best suited to the tasks most 
often performed in home labs.  For example, the HP 5334A would need 
one or two more digits to be maximally useful at the limits usually 
pursued by time-nuts.)  Note that these older counters will require 
some maintenance and may require repairs from time to time.

Best regards,


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