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

[russell]

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
>
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