[time-nuts] PRS10 time to lock

Bob Camp lists at rtty.us
Wed Aug 28 10:56:49 UTC 2013


Hi

They are after good ADEV out to the point that the loop bandwidth lets the gas cell take over. In some cases that can be a bit further out than others.

Bob

On Aug 27, 2013, at 10:09 PM, Ed Palmer <ed_palmer at sasktel.net> wrote:

> Yes, in many of the more recent Rb standards you're lucky if the crystal is ovenized at all.  But are you sure that they're after good ADEV?  I get the impression that the only thing they're interested in is low drift for the unit (e.g. for holdover purposes) since they're intended to be components in a system rather than lab standards.  Anything else is more luck than intent.  The PRS10 seems to be an exception in that it has an SC xtal.  Other than the 5065A, are there any Rb standards that use an SC xtal?
> 
> Ed
> 
> On 8/27/2013 6:24 PM, Bob Camp wrote:
>> Hi
>> 
>> The "OCXO" in most Rb's isn't all that great. They are after good ADEV, but tempco and aging aren't terribly important.
>> 
>> Bob
>> 
>> On Aug 26, 2013, at 1:34 PM, Nathaniel Bezanson <myself at telcodata.us> wrote:
>> 
>>> At room temperature, mine takes about 3-4 minutes heating until the lamp will start. You'll see RbMon showing SD2 and AD4 at max values, then they'll settle back into something sensible once it lights up. After that, you're watching the DS signal values and hoping the (large, small) turns into (small, large).
>>> Mine had a blown capacitor in the lamp circuit, thus it wouldn't ignite; SD2 and AD4 never budged. I opened it up to find a cracked tantalum cap: http://imgur.com/bASgB After replacing the cap, I now get lamp ignition but it doesn't achieve lock. (Photocell signal AD9 very low.) Once I swear I saw RbMon claim it had locked, about 6 minutes after power-up, but a moment later it was back to unlocked state and it's never repeated that feat. No idea what happened there.
>>> I'm wondering whether one can simply use it as a nice (albeit power-hungry) OCXO. If given 1pps from GPS, will the quartz discipline itself even without the Rb loop running?
>>> -Nate B-
>>> Stephen Tompsett (G8LYB)  wrote:
>>>>               Use the RbMon utility to monitor the unit's operation as it starts up to
>>>> confirm that the lamp is started and the photocell is detecting a signal.
>>>> Not long ago there were a number of units available for sale on Ebay
>>>> that appeared to have a lamp problem.
>>>> 
>>>> On 23/08/2013 02:10, Paul wrote:
>>>>> As I patiently wait for my PRS10 to lock I'm curious if there's a
>>>>> limit beyond which I should assume the unit is faulty.
>>>>> 
>>>>> It does produce abount 10MHz (+- .2 Hz) and the oven current dropped
>>>>> at what I assume is operating temperature.
>>>>> 
>>>> --
>>>> Stephen Tompsett (G8LYB)
>>>> 
>>>> 
> 
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