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" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
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 <[email protected]> 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 <[email protected]>
To: [email protected]; Discussion of precise time and frequency
measurement <[email protected]>; David <[email protected]>
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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