Hi I want to inform you that my FE-5440a now works fine. After a lot of reverse engineering i found that there was a parasitic oscillation of about 500 Khz !!! in the integrator amplifier ic (lm108). I replace the ic with an other ( the same type but 7 years earlier production !) and now the accuracy is in the range of 1E-11. Now i have to play with c-field adjustment to achieve better precision.
Regards Emmanouil Mantzaras ------ Original Message ------ Received: Mon, 04 Nov 2019 06:40:24 AM EET From: paul swed <paulsw...@gmail.com> To: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com> Subject: Re: [time-nuts] Dead 5061B Jim Is there any hope. I would believe so. CS tubes are pretty tough. As Scott says HV supplies but you measured those and they appear good as you say. So its a knock down drag out battle. You have nothing to loose so dig in. I wonder if the SRD may have popped. But its funny the ion pump is 0. That seems a bit odd. always a bit of crud in the tube that should make that kick up. My 10 cents. Regards Paul. On Sun, Nov 3, 2019 at 3:45 PM Scott McGrath <scmcgr...@gmail.com> wrote: > Have you checked the HV supplies? > > Content by Scott > Typos by Siri > > > On Nov 3, 2019, at 2:04 PM, AC0XU (Jim) <james.schatz...@ac0xu.com> > wrote: > > > > Time Nuts- > > This 5061B was working fine until a recent power failure, after which the > unit would not come on line (alarm light stayed lit). > > Major symptoms now: > > Beam I ; Second Harmonic; Ion Pump Supply are all 0 on front panel. All > other front panel readings are normal. (except for battery, which th unit > doe snot have). > > L4P2 signal is 16.832 MHz 1.7 V p-p (perfect - suggesting that A1 > synthesizer is fine) > > Going through 5-173 A12 Cesium Beam Tube Operational Checks: > > 5-175 Low Frequency Coil Check. Everything is fine except that tweaking > the external oscillator frequence/amplitude has no effect. Beam I is always > 0. > > The text says "If the beam current is not restored, it indicates a problem > in the the cesium beam tube power supplies (A11, A15, A18, or A19) or in > the cesium beam tube itself. > > A11 = Cesium Oven Controller - front panel reading is fine. Removed A11 > from the chassis and made the tests in 5-141. > Everything fine. +- 16V and -10V all fine; Cs oven voltage fine; the > thermistor tests out at 435 ohm vs. the 430 ohm on the label. > > A15 = Power Regulator Board - main +18.65V is fine > > A18 = +3.5KV supply - measured and is fine > > A19 = -2.5KV supply - measured and is fine > > I am inclined to conclude that the tube is dead. I don't understand why > that occurred suddenly in conjunction with a line power failure. > > Can I have any hope that the tube is still o.k.? Any ideas? > > Thanks! > > Jim > > > _______________________________________________ > 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.