Dear Hugh, I really enjoyed reading this! You have several cliff-hangers in there: Did you (HP) fix/reduce the top cover issue? Did you alter the setup to meet tighter specs? Did you fix the oven controller cable offset? What else war-stories do you got?
It is by war-stories one shares knowledge, lessons learned is not without its background and at least you have a great story. Cheers, Magnus On 12/20/18 12:36 AM, Rice, Hugh (IPH Writing Systems) wrote: > Hello Time Nuts, > I found this HP Application note in my archives, and attached a scanned copy: > > Application Note 52-4. Contribution of HP clocks to the BIH's International > Atomic Time Scale (IATS). > I also found a couple of archives for HP application notes for anyone who may > be interested: > http://hparchive.com/appnotes > https://www.keysight.com/main/editorial.jspx?cc=US&lc=eng&ckey=1127547&id=1127547&cmpid=zzfindclassic-app-notes > > > It is an interesting snapshot at the method of keeping the official IATS > time, and how HP Cesium standards are a major part of it, published in 1986. > > The author, Felix Lazarus, was a legendary Field Application Engineer (or > something like that) for HP in Europe, based in Geneva Switzerland. He was > obsessively fussy, and insisted that any Cesium Standard shipped to key > customers in Europe were first shipped to him, so he could verify acceptable > performance before the customer received the instrument. > > He would fire up the product, re-tune and re-align all the settings, and then > compare it to his house standard. If it wasn't up to his exacting standards, > he would keep tuning and testing until it was acceptable - to him. He was > looking for performance several times better than our published > specifications, which were 5 x 10e-12. He wasn't satisfied until is was > less than 2, or something like that. It drove us factory guys crazy. He > was a well-respected figure in the time keeping world, and would bash us for > shipping product that were not beating the specs by enough margin. > > I think he is the one that discovered the "top cover effect". If you removed > the top sheet metal cover from the instrument, the offset would shift by a > part in 10 to the 12th or so. If you put the cover on, and changed how > tight the screws were tightened, it would shift differently. I recall he > wanted us to fix this. > > I was the "Production Engineer" on the Cesium standards, a young BSEE college > graduate. I barely knew how a basic op-amp amplifier worked, and was > completely overwhelmed by the complexity of the Cesium Standards. "Go fix > the problem on the most accurate commercial atomic standard for sale in the > world, where if you change how tight a screw is, the performance shifts a > touch." It is safe to say that I didn't make this my highest priority. > There were theories that the root cause was subtle changes to the ground > loops with a change like this. The whole product used all the sheet metal > as a common ground, meaning that the ground return paths were not designed at > all, just left to chance. > > A related issue that I didn't work on was the "oven controller cable offset." > There was a big multi wire cable o the cesium oven heater controller, and > if you twisted it left vs. right before plugging it in, the offset of the > standard would change. > > > Working on the 5061B destroyed my confidence in my engineering abilities. I > didn't think I could solve "real" engineering problems, because of issues > like this. After working on the 5061B product for several years, I applied > for a job as an engineering manager over the frequency counter production > product line. During the interviews, my low technical self-confidence came > through, and the R&D management partners to this position were worried I > couldn't provide technical leadership to the other engineers. So, in true > HP fashion, my they sent me through the full scale HP R&D engineering > interview -about a half dozen deep 1:1 technical interviews with EE experts > in the lab. Turns out that I wasn't a dunce after all, just scarred from my > experience working on the cesium standards. I got the job. > > > I have a handful of other stories like this from my days inside HP frequency > and time division. Let me know if you want to hear more. Maybe Rick > Karlquist will tell some stories of developing the 5071! > > Hugh Rice > > > > > > > > > _______________________________________________ > 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.
