[time-nuts] Dead 5061B

[EMMANOUIL MANTZARAS]

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 <paulswedb at gmail.com>
To: Discussion of precise time and frequency measurement
<time-nuts at 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 <scmcgrath at 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.Schatzman at 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 at 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 at 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 at lists.febo.com
To unsubscribe, go to
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.