Brian Funny you mention the dirty emult. At the time I was wondering and if there was any insane way to get the Cs off the e multiplier. HV to ground or something to migrate them. Hold upside down and shake hard. ;-) Regards Paul
On Thu, Oct 4, 2012 at 4:22 PM, Brian, WA1ZMS <[email protected]> wrote: > Rick can correct me on this... > but my understanding is that it is > almost never a case of running out > of Cs from the oven, but that the > dynodes of the electron multiplier > become covered in used Cs and so > the ultimate SNR and effective beam > current falls to a point where there is > no dependable beam current left to > do much with. > > The tube that I sent to Paul, he was > able to get some more current by > running the Cs oven at a higher temp > and as such is vaporizing off LOTS of > Cs and can get a tiny bit of beam > current to work with. But it is a down > hill slide, since to keep the beam > current up with a "dirty" E-mult, over > time you need to keep running up the > Cs oven temp to the point where you > may just run out of Cs....or.... get an > E-mult that is so covered with used > Cs that there is no beam current to > work with. You can always try and > run up the E-mult voltage as well, but > you then run the risk of arcing in the > E-mult and an issue of burning up > the resistor divider stack that I believe > is part of the E-mult. > > I can see it now...... an end-of-life Cs > tube that needs 35kV on the E-mult > to get any beam current to work with! > : -) > > > -Brian, WA1ZMS > > On Oct 4, 2012, at 3:41 PM, paul swed <[email protected]> wrote: > > > Rick > > Well I have the old 5060 and 61 tubes and indeed they run out O gas. > > I am using a 5060 tube in a 5061 and the Frankenstein works though it has > > only a few Cs. But heck it all locks after 48 hours. > > So someone said with humor lets buy some 5071 tubes for a couple hundred > > each. > > Guess I could have some fun getting that into the 5061. Suspect that > would > > be the bride of Frankenstein then. > > Thanks for sharing the insights and experience. > > Paul > > WB8TSL > > > > On Thu, Oct 4, 2012 at 3:21 PM, Richard (Rick) Karlquist < > > [email protected]> wrote: > > > >> These ideas are "interesting". AFAIK, there is very little > >> chance of running out of Cs in many years, long past the > >> time when something else in the tube will have reached its > >> end of life. Where did this idea come from? Certainly, not > >> anyone working at HP, Agilent or Symmetricom. A LONG time > >> ago, if you bought a high performance 5061, the increased > >> Cs beam flow might have been an issue, but the amount of Cs > >> shipped with the tube was increased before the 5071A > >> such that running out of Cs is no longer an issue. > >> > >> If you turn off the Cs, you simply have a 10811 to connect > >> to your GPS. Except this 10811 has 10X the EFC range vs > >> a stock 10811. Again, this doesn't make a whole lot of sense, > >> IMHO. > >> > >> BTW, another "interesting" idea is degaussing the CBT. According > >> to Len Cutler, this is completely unnecessary in the 5071A. As > >> anyone who knew Len can attest, if he thought something was > >> good enough and didn't need to be improved, you could be > >> sure about that. For example, Len wanted us to use tantalum > >> filter capacitors for energy storage in the power supply. > >> Fortunately, we talked him out of that (actually the $100+ > >> cost helped to convince him). > >> > >> Due to customer demand (the customer is always right :-) the Santa > >> Clara Division eventually released a degausser. One of the reasons why > >> this is not necessary in the 5071A is the Zeeman line measurement > >> of the magnetic C field. The 5061 was open loop. So again there > >> may have been a grain of truth behind the folklore. > >> > >> Rick Karlquist N6RK > >> Member of the 5071A design team > >> > >> > >> On 10/4/2012 9:45 AM, Tom Van Baak wrote: > >> > >>> Bob, > >>> > >>> Right, not good. There should be a fault message associated with it. > >>> Check the internal log. > >>> > >>> OTOH, to conserve cesium, I've heard that some people run 5071A in > >>> standby mode most of the time and only turn on the cesium for a > fraction of > >>> an hour a day or a week (to recal the quartz). Running in this standby > mode > >>> is also advisable if one wants the best short-term performance out of a > >>> 5071A, without the loop noise. In this respect it's just like a GPSDO > - you > >>> get the best short-term performance if you turn off disciplining. > >>> > >>> /tvb > >>> > >>> Hi > >>>> > >>>> Is "Cs oven: 0.0V" a good thing on a 5071A? > >>>> > >>>> I suspect not, since either it or GPS is off frequency. > >>>> > >>>> Bob > >>>> > >>> > >>> > >>> > >>> ______________________________**_________________ > >>> time-nuts mailing list -- [email protected] > >>> To unsubscribe, go to https://www.febo.com/cgi-bin/** > >>> mailman/listinfo/time-nuts< > 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< > 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. > _______________________________________________ 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.
