[time-nuts] GPDSO is working

[Bob Camp]

Hi

You will need to fine tune the firmware settings for that OCXO. 

Bob

On Jul 12, 2013, at 11:27 AM, Bob Stewart <bob at evoria.net> wrote:

> Hi Bob,
> 
> OK, you got me: time as in about 120 minutes.  =)  It's mostly "+", with the occasional "-" for about an hour or so.  Then, it wavers back and forth between "+" and "-", but the long term trend is still very slowly "+".    So, I guess the OCXO needs more time to "settle in"?  My OCXO is a Trimble 34310-T.
> 
> As soon as I can get the serial port wiring done I'll be able to tell if it's in "position hold" mode.  I suspect it's not, as it doesn't have a battery on-board.  I did wind up mounting a Lithium 3V backup battery, using a holder from an old motherboard.
> 
> I'll have to look around to see if anyone has any software to graph the DAC track for this board.
> 
> Bob - AE6RV
> 
> 
> 
> 
> 
>> ________________________________
>> From: Bob Camp <lists at rtty.us>
>> To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>> Sent: Friday, July 12, 2013 8:47 AM
>> Subject: Re: [time-nuts] GPDSO is working
>> 
>> 
>> Hi
>> 
>> On Jul 11, 2013, at 11:59 PM, Bob Stewart <bob at evoria.net> wrote:
>> 
>>> After ham-fistedly breaking a few things, I've finally got my GPSDO working. (does happy dance)  Now that it's had some time to warm up
>> 
>> Time as in minutes, or as in a couple of days? If you look at the plot in the QEX article, a day or so is the expected "warmup" period.
>> 
>>> I see that it's started wandering around +/- a couple of counts from sample to sample (16 seconds). 
>> 
>> If it's + *and* - then the gizmo is driving down the middle of the road. If it's always + or always - then it's likely not yet locked.
>> 
>>> Is this because the UT+ is not set to timing mode? 
>> 
>> The UT needs to be in "position hold" mode with a proper (24 to 48 hour) survey on it's location for best performance. It should not be +/- 100 ns even without this. 
>> 
>> Is your VCXO a 10811? Does it have the same sensitivity as a 10811? If not, you may need (per the article) to make some firmware changes.
>> 
>> Bob
>> 
>>> Putting in an RS-232 (or USB) to TTL adapter, switchable between the UT+ and the VE2ZAZ board, is pretty much next on my schedule.  I've got an adapter I made many years ago, but it's not suitable for mounting in the box, and there's no simple way to hook it up to the UT+ at the moment.
>>> 
>>> Bob
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