Hugh, Well I sure enjoyed the story and though I won't say I am scarred by Cesiums, they have proven just how little I know more then a few times. Like you it took some 3 years to get the monster working. Its called Frankenstein. You guessed how its made. Regards Paul WB8TSL
On Wed, Dec 19, 2018 at 8:07 PM Rice, Hugh (IPH Writing Systems) < [email protected]> 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 -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
