[time-nuts] Lucent RFTGm-II-XO / Lucent RFTGm-II-Rb / NT BW50AA

[Jeff Blaine]

Hi Bob,

Thanks for your comments.  The highest precision thing in my lab is a 
5338a and that's only if I set the gate time to something really long so 
that it renders a full 12 digits of info.  Other than a "I wanna be a 
time nut so let's see what it will do" - I never need anything near that 
in reality.  So let's say what I want to be able to see is 0.1 Hz 
resolution on a 50 Mhz test frequency.  So your 0.1 ppb is a good 
observation.

Do you have any thoughts on PN of the 3?  Ive not found plots yet for 
the Lucent boxes but know the NT I have is middling on a good day.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 12-Feb-19 9:17 AM, Bob kb8tq wrote:
> Hi
>
> Pretty much all of these big old telecom beasts are “good enough” for “typical use”. The gotcha
> is that both of those terms are very much lacking in precision. Since this is a precision sort of
> thing, that may not be ideal :)
>
> If 0.1 ppb is good enough for what you are doing, then they all should be fine. If you need 0.001 ppb,
> then none of them are likely to do what you need to do. Between those two limits, things like antennas,
> survey locations, lab temperature, and the accuracy definition you use all get into play. Yes, you *can*
> have some unusual cases (your lab goes from -20 to +90 (F of course …) on a daily basis. For anything
> reasonable, the limits above are pretty good.
>
> If time rather than frequency *is* the goal, then one of these GPSDO's is not really what you want.
> The time pulse output from a good GPS module is likely closer to UTC (after some math) than the
> output of the GPSDO.
>
> Bob
>
>> On Feb 11, 2019, at 9:57 PM, Jeff Blaine <KeepWalking188 at ac0c.com> wrote:
>>
>> I have these 3 systems operational here and wonder what is the "best" of the sources?
>>
>> The local use for the reference is as a time base for test equipment.  Nothing hyper critical in the way of end-use requirements - but after running the NT GPSDO for a few years and watching the Lucent box collect dust, I wonder if I have got that backward?
>>
>> The lucent has a 10 Mhz output on the front panel of the RB but the XO would need a tiny bit of modification to have 10 Mhz instead of the current 15 Mhz.
>>
>> There is a lot of data on http://leapsecond.com/u/sims/gpsdo17/ but I don't see the RFTG XO on there - which I assume is due to it's native 15 Mhz Fo vs. 10 Mhz for the rest of the field.
>>
>> Appreciate any advice you may have for a (very) novice 'nut.
>>
>> 73/jeff/ac0c
>> alpha-charlie-zero-charlie
>> www.ac0c.com
>>
>>
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