----- Original Message ----- From: "David Welch" <[EMAIL PROTECTED]> To: "Dave Carlson" <[EMAIL PROTECTED]> Sent: Sunday, February 10, 2008 9:24 PM Subject: Re: [time-nuts] cs beam tube failure???5071a tube is dead now...
> Dave.. > > I did get a case # with agilent and they said to call symetricom and see > what they would do?The guy I talked with did not know much about that > division other than it had been sold but insisted they(agilent)only offered > a 3 yr. warranty.. > > I have had this unit in standby now for at least 24 hrs and the pump current > when I first switched it lowered to .4 and .2, even an 0.0 for a second..but > pretty much constantly switched between .4 and .2ua.. > > Now the interesting part when I just looked later this afternoon it is back > up to .6 again with an occasional .4 > (in standby)..BUT the Cs oven shows 0.1 volts and will go down to 0.0 for a > second or so then back up.. > This is not addressed in the manual(at least I could not find it)should it > not be 0.0 in standby???.. > when I toggle the menus very fast(they are next to each other) this .1 volt > rise seems to change when the ion pump goes to .6...which it is now almost > all the time..(unit still in standby..) > > Bad news..I just switched the unit into operate and watched all values very > closely..when the Cs. voltage started to drop during warm up, started out > cold at 20.8 and when the oven kicked in,about 13 or so volts, the status > said raising emult voltage(it has always said lowering it in the past) I sat > there and waited and (BEEP)..Fatal error ...see log.. > so I checked the log and got a error (low Cs signal 3 with max emult)..now > the emult is at 2553.. am powering unit down now to try to restart.. > > ----- Original Message ----- > From: "Dave Carlson" <[EMAIL PROTECTED]> > To: "David Welch" <[EMAIL PROTECTED]> > Sent: Saturday, February 09, 2008 2:41 PM > Subject: Re: [time-nuts] cs beam tube failure??? > > > > David, > > > > "when I called them they said these were no longer under factory warranty > > because Agilent only offered a 3 yr warranty..and this was one of the very > > last Agilent units made.." > > > > Not true. In any case Agilent no longer owns the warranty since the entire > > business and all obligations were sold to Symmetricom in July 2005. > > > > At the time of the divestiture the 5071A chassis had a standard 1-year > > factory warranty and the High-Performance CBT had a 5-year factory > warranty. > > > > Anyone at Agilent should not be giving out warranty information because > they > > do not have the legal right to make those statements any longer. > Symmetricom > > owns the rights along with any obligations. > > > > As to the Ion Pump current dropping to .4 and .2 uA during standby, that > > makes sense. In standby the Cs oven is off and the additional Cs floating > > through the CBT adds to the load on the pump. > > > > It's good that you do see some change in the Ion Pump current. That means > > it's functioning properly and that the .6 uA is not an artifact of the > > electronics. > > > > Dave > > > > ----- Original Message ----- > > From: "David Welch" <[EMAIL PROTECTED]> > > To: "Dave Carlson" <[EMAIL PROTECTED]>; "Discussion of precise time > > and frequency measurement" <time-nuts@febo.com> > > Sent: Saturday, February 09, 2008 9:26 AM > > Subject: Re: [time-nuts] cs beam tube failure??? > > > > > > I opened the box for the first time,,the unit was new and still in the vac > > bag..the ion current started out and has remained at .6ua..always locks in > > about 15-18-min..one other unit he had for sale that the seller had opened > > and had running had a (for two days)had a emult of 1715 and also .6 ua > > current..when I got there to pick up my unit his emult had also dropped > from > > 1715 to 1700 in 24 hrs time.. > > > > one note when I power down or put my unit into standby the pump current > will > > go down to .4 and even .2 but not for long ,,,after running for several > days > > it usually goes back up to .6..I just had it in standby last night for a > few > > minutes and it is still at .4 ua today.but now shows 1295 emult volts... > > > > the unit locked for its first time after 2+ years in storage in 21 > > minutes...the calibration certificate shows a manuf date of may > 11,2005..but > > when I called them they said these were no longer under factory warranty > > because agilent only offered a 3 yr warranty..and this was one of the very > > last agilent units made.. > > ----- Original Message ----- > > From: "Dave Carlson" <[EMAIL PROTECTED]> > > To: "Discussion of precise time and frequency measurement" > > <time-nuts@febo.com> > > Sent: Saturday, February 09, 2008 1:47 AM > > Subject: Re: [time-nuts] cs beam tube failure??? > > > > > > > David, > > > > > > > I had a similar concern about a brand new 5071a I just purchased,This > > unit > > > is dated may of 05 and was first powered up Jan 2 of this year.. > > > > > > If it's really been turned off all that time, I'm surprised that it was > > able > > > to power up. Was the Ion Pump current much higher for some period of > time > > > before it came down to 6 uA? How do you know it was manufactures in May > > > 2005? > > > > > > > the ion pump has remained constant at 6 ua > > > > > > This may be as low as it's going to get. You might try putting the 5071A > > in > > > standby mode for 24 hours or so, to allow just the Ion Pump and not the > Cs > > > Oven to operate. It might bring down the internal gassing a bit. But > then > > > again that may be as low as you get. It's not abnormal, especially for > > older > > > CBT, or one that has been allowed to accumulate internal vapor pressure. > > > > > > > but I the electron mult volt has been dropping about 1-2 volts per day > > > > since then.it started out at 1525 and is now at 1297 and still falling > > > > > > This is fine, and well within expected operation. The 5071A > automatically > > > adjusts the EMult voltage to maintain the 100 nA beam current. You have > > > plenty of room to drop without concern. The good thing is that the lower > > you > > > go, the more headroom you'll have when ultimately the beam current > begins > > to > > > weaken and need increasing EMult to maintain. It should eventually > flatten > > > out before it starts to rise. If it does get down to 800 to 600 volts > > > without flattening out, then it will very likely have a problem. It may > be > > a > > > symptom of lots of internal gassing that is getting too much background > > > signal to the EMult dynode. No cure for that but to send it in for > repair. > > > > > > > all the other parameters are fine but I noticed the osc freq control > has > > > > been dropping also it is now at > > > -6.84,started out at -5.50.. > > > > > > This is fine. You don't have to worry until and if it gets to 50% or > more. > > > Then it's time to tune it in, which is a bit tricky. Get copies of the > O&P > > > and Service manuals from the Symmetricom web site in PDF format and > you'll > > > have many of these answers. > > > > > > > do you think these is a problem with this tube?it is a high > > > perf..should still be under warranty as the manual says there is a 5 > year > > > warranty on tubes 4240 prefix.. > > > > > > You appear to have purchased a good 5071A. Did you buy it used? One > > obvious > > > question is: Is it locked? > > > > > > Dave > > > > > > _______________________________________________ > > > > > > ----- Original Message ----- > > > From: "David Welch" <[EMAIL PROTECTED]> > > > To: "Discussion of precise time and frequency measurement" > > > <time-nuts@febo.com> > > > Sent: Friday, February 08, 2008 9:59 AM > > > Subject: [time-nuts] cs beam tube failure??? > > > > > > > > > Dave, > > > I had a similar concern about a brand new 5071a I just purchased,This > unit > > > is dated may of 05 and was first powered up Jan 2 of this year..the ion > > pump > > > has remained constant at 6 ua but I the electron mult volt has been > > dropping > > > about 1-2 volts per day since then.it started out at 1525 and is now at > > 1297 > > > and still falling all the other parameters are fine but I noticed the > osc > > > freq control has been dropping also it is now at -6.84,started out > > > at -5.50..do you think these is a problem with this tube?it is a high > > > perf..should still be under warranty as the manual says there is a 5 > year > > > warranty on tubes 4240 prefix.. > > > have you ever run into this before?any suggestions..Thanks David > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@febo.com > > > To unsubscribe, go to > > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > > > > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@febo.com > > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > and follow the instructions there. > > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.