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 _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
