Hi An "E series" Thunderbolt is about 4X the size of the later Thunderbolt, sometimes called an E. Yes it's very confusing.
If the OCXO is about 1" on a side and the unit is maybe 1.5" wide, then you have the later version of the Thunderbolt. Probably the best way to confirm this and eliminate the confusion would be a picture. Bob On Feb 27, 2013, at 7:35 PM, Paul Berger <[email protected]> wrote: > I did peek inside the E not long after I got it and I do remember that the > OXCO looks very different, it is much smaller than the one on my Nortel unit. > If it is the OXCO I can always source a potentially better OXCO and then I > can have more fun playing with it. Being a technician I really enjoy fixing > things and seeing them work again. One other big difference in the E model > is it takes a single 24VDC power input and has a little switcher module in it > to generate the voltage the GPSDO actually uses, this is similar to the setup > on the Nortel unit, however it did not look to be built nearly as good. I > will give it a little more time and if it does not improve I will pull it out > of its box and start to poke around inside. > > Paul. > > On 2/27/13 8:23 PM, John Miles wrote: >> Sounds like a bad OCXO. The crystal frequency jumps slightly, and the >> disciplining loop then has to compensate by steering the DAC voltage >> through the loop filter. If that's the problem it may get better if you >> leave it running for a few more weeks. >> >> The smoking gun is the attack/decay characteristic of the DAC adjustment. >> At least in theory, no issues on the GPS side of the loop should result in a >> fast leading edge at the DAC. >> >> I haven't seen any Thunderbolts with genuinely bad OCXOs yet, although some >> of them are definitely better than others. The Thunderbolt-E, however, is a >> very different model than the ones that are normally found on eBay. Almost >> everything you hear about a "Thunderbolt" refers to the older non-E version. >> >> >> I've heard (but can't exactly cite) that the Thunderbolt E models were a >> reduced-cost, higher-volume product. If that's true, you can assume that >> they don't use the same OCXOs, because those OCXOs were much better -- and >> would have been more expensive -- than they had to be. >> >> (The Thunderbolt E should not be confused with the more common Thunderbolts >> running 'E'-level firmware.) >> >> -- john, KE5FX >> >>> Hi, Paul. Glad to see you made it here. For the time-nuts; Paul and I >>> have spoken about these issues, and I have had similar experience. The >>> only thing I would add is the the spikes to seem to occur less >>> frequently with a better antenna placement, but when they start to >>> cluster, they fire off one every two or three seconds, sometimes >>> faster. >>> >>> JimT >>> >>> On Wed, Feb 27, 2013 at 2:08 PM, Paul Berger <[email protected]> wrote: >>>> Hello all: >>>> >>>> I am an electronic technician with 30+ years experience fixing >>>> computers. In my spare time I like to play with old computers and >>>> electronics. Recently I got bit by the precision timing bug, partially >>>> after running across the wonderful leapsecond.com site, which lead me >>>> here. First I got a FE-5680A, then after reading some of the archives >>>> here I bought a Nortel / Trimble 45000 GPSDO and still later a used >>>> Thunderbolt-E... >> _______________________________________________ >> 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. _______________________________________________ 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.
