[time-nuts] [qs1r] Looking for good, cheap, external reference

Bob Camp lists at rtty.us
Thu Sep 23 00:57:24 UTC 2010


HI

Opening the box to be sure there's not a dead spider in there is always a good idea...

The old oscillators all went out before firmware 3.0. Manufacturing dates past end of 2000 should all have a better oscillator. You could test it for phase noise and short term stability, but pulling the cover is *lots* easier.

Firmware rev does show up in software. Anything past 2.1 is fine. The only reason to watch for 3.0 is that's what the e place sellers key into. 

The temp sensor is the one that moves in real small steps. The bad one moves in (1/2 degree???) big steps. 

All of that (and much more) is visible if you bring up Lady Heather and see what's going on.

Bob

On Sep 22, 2010, at 7:58 PM, russell wrote:

> Is there anyway to tell without opening the box if you have:
> 
> 1)  "better oscillator"  (=Trimble labeled) Anything visible from SW (Tboltmon or LH)?  Any behavior fingerprint?
> 
> 2)  "newer firmware"  (=rev 3.00)    Does show up in SW.
> 
> 3)  "newer brain dead temp sensor"  (=                        ?).  Anything visible from SW (Tboltmon or LH)?  Any behavior fingerprint?   What is the new sensor you changed to?
> 
> Thanks.  Russell
> 
> 
> ----- Original Message ----- From: "Ed Palmer" <ed_palmer at sasktel.net>
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Sent: Wednesday, September 22, 2010 6:39 PM
> Subject: Re: [time-nuts] [qs1r] Looking for good, cheap, external reference
> 
> 
>> And if you buy a newer unit with the better oscillator, new firmware, and newer (but brain-dead) temperature sensor, it's trivial to replace the sensor.  It took me longer to take the unit apart than to change the chip and I don't have a lot of experience with surface mount.
>> 
>> Ed
>> 
>> Bob Camp wrote:
>>> Hi
>>> 
>>> That's my feeling. The firmware isn't the issue. The OCXO and the temp sensor are the important points. The firmware is just an easy way to get the right OCXO.
>>> 
>>> Bob
>>> 
>>> 
>>> 
>>> On Sep 22, 2010, at 7:00 PM, Mark Spencer <mspencer12345 at yahoo.ca> wrote:
>>> 
>>> 
>>>> Would a newer unit with the 3.00 firmware, the trimble branded OCXO and the older temperature sensor be one of the better (or perhaps best ?) TBOLT combinations ?
>>>> 
>>>> 
>>>> 
>>>> ----- Original Message ----
>>>> From: John Miles <jmiles at pop.net>
>>>> To: lester at veenstras.com; Discussion of precise time and frequency measurement <time-nuts at febo.com>; David <n7aig at yahoo.com>
>>>> Sent: Wed, September 22, 2010 12:42:06 PM
>>>> Subject: Re: [time-nuts] [qs1r] Looking for good, cheap, external reference
>>>> 
>>>> 
>>>> 
>>>>>      John, unless I am going mad, the ADEV plots for both auctions you
>>>>> mentioned look the same - maybe the bad one has been replaced since
>>>>> you posted your message?
>>>>> 
>>>> The black-and-white plot that everybody uses is from the original
>>>> Thunderbolt data sheet, which was way conservative even for the older units.
>>>> Towards the bottom of the 290308733659 auction, though, the seller has
>>>> appended a half-dozen or so photographs of a TSC 5120A screen showing what
>>>> are (for a Thunderbolt) some weak results.  The ADEV plot shows poor
>>>> long-term disciplining and the PN plot doesn't look good either. Possibly
>>>> he's using a noisy reference, or the unit was tested during a 2-day-long
>>>> earthquake.
>>>> 
>>>> I've never seen one do ~-88 dBc/Hz at 10 Hz.  Even my original one with the
>>>> lower-quality OCXO was good for -105 dBc/Hz, while the ones with the
>>>> Trimble-labelled OCXO can do -130 or better.  Likewise the 'good' ones will
>>>> do several dB better than the -150 dBc/Hz broadband floor he shows.
>>>> 
>>>> I've also never seen one in a black anodized(?) housing like that (has
>>>> anyone else?)  Mark is right in that the 3.00 firmware doesn't necessarily
>>>> do much for you, but the newer units also had the good OCXOs, which IMO is
>>>> more important than the temp sensor.
>>>> 
>>>> -- john, KE5FX
>> 
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 




More information about the time-nuts mailing list