It looks like since last Oct the osc jumped frequency and has become less stable. This is not unheard of for an ocxo. It may be time to replace with a true Trimble Thunderbolt. A couple are now on ebay for 2-300$. It is possible to replace the ocxo, assuming nothing else is wrong with the circuit.
On Thu, 26 Sep 2019 13:21:25 -0400, Roger Rehr W3SZ wrote: >Hi All, >Sorry I forgot to attach the freq vs DAC voltage table to the email that >I just sent: >DAC V- Freq >+5.0- - - - 9.999.961 >+0.0- - - - 9.999.985 >-3.0- - - - 9.999.998 >-3.5- - - - 10.000.000 >-3.8- - - - 10.000.001 >-4.0- - - - 10.000.002 >-4.5- - - - 10.000.004 >-5.0- - - - 10.000.006 >So the oscillator is not "centered" on 10.000.000 anymore. >73, >Roger >W3SZ >On 9/26/2019 1:06 PM, Roger Rehr W3SZ wrote: >> Hi Nigel, and Bob, and Bill! >> >> Thanks for the notes!- I very much appreciate your helpful comments.- >> I will give my responses to all of your helpful posts here.- Sorry for >> the delay in responses.- The reason for the delay is that my >> Thunderbolt is at a remote site and I can communicate with it via Lady >> Heather remotely, but I had to drive out to the site to do the tests >> with an HP 5342A frequency counter and pulse analysis of the pps >> port.- I drove out to the site today. >> >> First, Bob and Bill, >> >> 1. >> DAC set to +0.5 V gives significant frequency errors:- HP counter >> reads 9.999.984 MHz and osc error as reported by LH is 1,68x,xxx.xx >> ppt.- Interestingly, at this voltage pps error is flipping between +50 >> and -50. >> >> The DAC voltage that minimizes both counter error and pps/osc error as >> reported by LH is around -3.553 V.- This is dramatically different >> than the setting last October when all was working well, as you know. >> >> With DAC voltage -3.553 V the osc error and pps error are reduced, but >> they jump around quite a bit: >> pps short-term variation is for example between about +50 and -50 and >> osc short term variation is between about +5000 and -5000.- HP counter >> reads 10.000.000 MHz. >> >> Even when I have the DAC close enough to optimum that my counter reads >> 10.000.000 MHz and the osc error is flipping around both sides of >> zero, the unit stays in "Power-up" mode and the DAC voltage stays at >> wherever I set it (either using d>>s or &>>i and then power cycle) and >> does not vary. >> >> >> 2. >> I get a 10 usec duration +5V pulse every 1.00 seconds from the PPS >> port, as per specifications.- I cannot give you greater precision than >> that on the pulse interval. >> >> >> Nigel, >> >> I agree that something appears odd with this unit that had been >> running with no problems for at least a year at my location.- There >> have been no known system / config changes by me, although there is >> always the chance that I fat-fingered something when playing with the >> Lady Heather display at some point. >> >> The receiver self identifies as a TSIP (Trimble TSIP Binary) receiver >> when Lady Heather starts up.- The receiver type is not specified in my >> cfg file, which instead has the default line /rx which as you know >> means auto-detect receiver type. >> >> I had assumed that the "Nortel NTGS/NTBW" designation that you mention >> and that appears on the Lady Heather parameter display had something >> to do with Trimble having supplied the unit I now have to Nortel and >> this "Nortel NTGS/NTBW" designation being a custom ID placed in the >> firmware so that the unit would be "branded" as Nortel.- This >> supposition is consistent with line 2170 of the heather.txt file which >> says "Trimble telecom GPSDOs (NTBW,NTPX,NTGS,etc)".- There is also a >> line in the heather.pdf file that says, "Note that non-Thunderbolt >> GPSDOs (such as the NTBW and NTPx telecom devices) do not all support >> saving disciplining parameters to EEPROM and some do not allow users >> to change the disciplining parameters. You can use "/d" command line >> options for setting the PLL parameters from the command line. If you >> run the auto-tune command on non-Thunderbolt devices then only the >> satellite elevation mask (and perhaps the signal level mask) values >> will be set". >> >> The physical unit is labeled "Trimble THUNDERBOLT", so I guess, >> looking at all of the data, that I have a Trimble / Nortel device. >> >> But the issue of whether it is a Nortel/Trimble Thunderbolt or just a >> Thunderbolt wouldn't cause the current problem that I am having now in >> a unit that previously worked perfectly for me. >> >> Just so you know that my heather.cfg file is "OK" and not responsible >> for any problems, here it is: >> >> /9 >> /rx >> /br=9600:8:n:1 >> /ro=1* >> /tz=-5EST/EDT >> /b=1 >> /tb=W3SZ >> /gm >> /gw=0 >> /gqw >> /gcs- >> /gcg >> >> To further document that this issue is not a "setup" problem, I did >> another factory reset of the unit and then did not use Lady Heather >> but only monitored function with TBoltMon.exe and I did not do any >> setup with that utility until the self survey was done and more than >> two hours had passed, and then I only set and saved the position. >> Function and- results were unchanged, and the unit was still stuck in >> Power-Up mode and DAC voltage was still stuck at zero, but everything >> else was normal according to the TBoltMon readouts. >> >> Thanks again and 73, >> >> Roger >> W3SZ >> >_______________________________________________ >time-nuts mailing list -- time-nuts@lists.febo.com >To unsubscribe, go to >http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >and follow the instructions there. Bill Beam NL7F
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