[time-nuts] Tale of Two GPStars...

Fri Jun 5 14:40:32 UTC 2020

I just proved my memory isn’t what it used to be. My unit is a GPStat Frequency Measurement System, Model 345-200. Not a GPStar as I thought. I just dug it out and the label on the bottom says input +5, +12V 3W. I’ll dig into it later as I have another dig to do - 35’ trench 6” wide, 18” deep for power to a utility building. 

Steve

> On Jun 5, 2020, at 9:10 AM, paul swed <paulswedb at gmail.com> wrote:
> 
> Steve and yet another GPStar.
> My units are older and just GPStar by Odetics and use ocxo.
> These old units actually had external down converters that are quite
> complicated but nicely done.
> The din plug was +5 and +12. 2 pins for each plus grounds.
> Yours may be different if newer. But as you guessed really easy to figure
> out.
> Regards
> Paul
> WB8TSL
> 
>> On Fri, Jun 5, 2020 at 10:03 AM Steve - Home <steve-krull at cox.net> wrote:
>> 
>> I have a GPStar that hadn’t been used in a few years. I’ve misplaced the
>> wall wart power supply. Could someone pass along the output voltage and
>> current numbers of the wall wart, please? I think I can figure out the DIN
>> connector pin numbers but that would be helpful, too. My manual is pretty
>> sparse in that area. If I recall it says “plug in the AC adapter”...
>> 
>> Thanks!
>> 
>> Steve K.
>> WB0DBS
>> 
>> 
>> 
>>>> On Jun 4, 2020, at 10:00 PM, paul swed <paulswedb at gmail.com> wrote:
>>> 
>>> Somebody else actually has a GPStar (Odetics) and working?
>>> My units stopped working about 4 months ago. They are circa 1994 as I
>>> recall. Had 2 neither would work. Have one now as I used the case and
>> rack
>>> mounts for another project.
>>> These are much older then what you have as the GPS receiver is actually
>>> discreet components.
>>> Regards
>>> Paul
>>> WB8TSL
>>> 
>>>> On Thu, Jun 4, 2020 at 8:59 PM Bruce Lane <kyrrin at bluefeathertech.com>
>>>> wrote:
>>>> 
>>>>       After many moons, my trusty GPStar 365 (updated to a 565 through
>>>> firmware and a receiver change) finally bit the dust. Symptom: It kept
>>>> flipping between 'Coasting' and 'Recovering,' never quite reaching
>>>> 'Locked.' The DAC value either ended up maxed (65534) or min'd (00000).
>>>> 
>>>>       Contacted Tim Gavin at Zyfer-FEI for advice. Strongest
>> possibility:
>>>> OCXO went south. Tried manually setting the DAC for mid-point (32768)
>>>> and manually tweaking the coarse tuning on said OCXO against a
>>>> known-good 10MHz source of equal precision (translation: Another GPSDO).
>>>> 
>>>>       Didn't work. Tried replacing the OCXO itself, and doing the
>>>> alignment
>>>> trick. Still no joy.
>>>> 
>>>>       Considering the lack of schematics: Emit large sigh, put unit
>>>> aside,
>>>> start searching Ebay for replacement.
>>>> 
>>>>       Found a late-model (black case) 565-310 for a reasonable price,
>>>> bought
>>>> it. Arrived a week later (yesterday at work). Opened it up, delighted to
>>>> find I got a better deal than I thought in that the thing's got a
>>>> rubidium module (FE-5650A to be exact).
>>>> 
>>>>       Did initial power-up/burn-in test with a local GPS antenna; Unit
>>>> went
>>>> to TFOM 4 and 'Locked' within a half-hour and stayed that way all day,
>>>> DAC number just slightly above mid-point.
>>>> 
>>>>       However -- Date way off due to outdated Motorola UT+ receiver
>>>> module.
>>>> Replaced said UT+ with the M12M drop-in module from Synergy GPS. Fired
>>>> up -- and got NO satellite tracking ID's!
>>>> 
>>>>       Mutter something vulgar. Do more poking around. Suddenly realize
>>>> the
>>>> firmware in the replacement 565 is at 1.06, while my original unit was
>>>> at 1.08. "I wonder if..."
>>>> 
>>>>       Swap 1.08 firmware chip into replacement 565. Power on. Goes
>>>> through
>>>> factory reset -- and comes up perfectly normal! Sat numbers appearing on
>>>> tracking report. Just checked it a moment ago (about 15 minutes after
>>>> initial re-power) and it's at TFOM 4 / Locked! And it stayed that way
>>>> through a 24-hour burn-in check.
>>>> 
>>>>       Conclusion: In the 565 series, you need version 1.08 firmware to
>>>> support Motorola's M12, or similar replacements.
>>>> 
>>>>       And I'm still amazed I lucked out with the rubidium module. ;-)
>>>> 
>>>>       Keep on tickin'...
>>>> 
>>>> --
>>>> ---
>>>> Bruce Lane, ARS KC7GR
>>>> http://www.bluefeathertech.com
>>>> kyrrin (at) bluefeathertech dot com
>>>> "Quando Omni Flunkus Moritati" (Red Green)
>>>> 
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