There were field upgrades from HP5370A to B, I believe offered through the HP field services operation. I have an A->B converted unit. I believe it has the original front end, but the “B” firmware. It has been a while since I opened it up.
Sent from my iPhone > On Jul 20, 2019, at 10:35, Taka Kamiya via time-nuts > <time-nuts@lists.febo.com> wrote: > > Thank you. > I really do not want to buy from eBay. So far, none showed up with zero > problems. There's always something. My intent is to lock it to house > standard which is a GPSDO. I have lots of 10811 here but I don't know when > they were made. All I know is they are all 10811-6011. You are right - > especially for an instrument like this, standard is extremely important. > > --------------------------------------- > (Mr.) Taka Kamiya > KB4EMF / ex JF2DKG > > > On Saturday, July 20, 2019, 11:02:19 AM EDT, Bob kb8tq <kb...@n1k.org> > wrote: > > Hi > > If you are buying them on eBay, it is not at all clear which OCXO your A or B > will show up > with. The 10811’s get swapped back and forth with earlier units in a lot of > used gear. One > might *think* it’s a one way exchange, but I’ve seen it go both ways. > > If you lock the counter to an external standard, it really does not matter a > lot which OCXO > is in it. > > Bob > >> On Jul 20, 2019, at 4:21 AM, Frank Stellmach <frank.stellm...@freenet.de> >> wrote: >> >> Hi Mr. Taka Kamiya, >> >> the B version has a 500MHz front end, copied from the HP5345A, with a >> matched pair of amplifier / Schmitt trigger hybrids. >> The A version has separate amplifier and Schmitt trigger ICs. >> >> There were also changes on the trigger circuit. >> >> Then the B version has a simplified µP board, has the OCXO (10811-60111), >> which is a must for absolute T.I. and frequency measurements. >> >> Maybe the firmware was also improved a bit, I think mainly concerning the >> GPIB steering of the trigger circuit. >> >> This T.I. counter is supposed to be superior over others of that era, >> because this special time interpolator was more linear. >> >> I really love mine, so I don't want to sell it. >> >> Frank >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
