[time-nuts] Re: HP5061 offline management.

[paul swed]

Indeed Andy that is what numbers of time-nuts do with the 5061 as I
mentioned in the post. But for those of us reducing power consumption I
offer a way to do that with pretty minimal effort.
I work with a fellow that has 2 5061s that bell labs in NJ throughout many
years ago. (So will guess the tubes are dead) He is a ham and like you uses
the OCXO. The CS has actually never been turned on. He doesn't know how.
That was quite a surprise. It lives in his barn no less.
So most likely we will make a run at actually firing it up.
Regards
Paul
WB8TSL

On Fri, Aug 6, 2021 at 9:24 AM Andy Talbot <andy.g4jnt at gmail.com> wrote:

> I have a 5061A that has been sitting in my shack for over 25 years.   I
> keep it in  standby, using just the OCXO as a casual reference, good for
> less than 1 PPM.  I check the 1PPS output against GPS using a counter timer
> and tweak the front panel pot a few times a year to keep it spot on.
> When high accuracy is needed, perhaps a few times a year, Cs is activated
> and it typically comes up to satisfactory accuracy is around an hour - I
> usually leave it two hours.
>
> Yes it consumes a few tens of watts, but I'm quite prepared to spend the
> few pence per day that costs :-) to keep the tube fully pumped and ready to
> go.
>
> I replaced the NiCd battery pack which was completely dead when I got the
> unit with a LM317 and float charged 24V lead acid batteries.
>
> Andy
> www.g4jnt.com
>
>
>
> On Thu, 5 Aug 2021 at 23:26, paul swed <paulswedb at gmail.com> wrote:
>
> > Was talking with another time-nut on the best way to use the HP5061
> Cesium
> > to protect the tube. I have read over the years that some people let the
> > system run but with the CS oven off.
> > This consumes 19.4 watts or about 14KWH/month.
> > But has the advantage of a nice local reference and the tube is pumped
> > down.
> > I however leave my units completely off and run them every 2 months. The
> > downside of this is that when the ion pump clears the tube when the CS
> oven
> > is turned on there is a crud burst and the ion current reading can go
> > significantly up. Then has to pump back down a number of times.
> > There is a better way.
> > Leave just the 3500V supply run. Disconnect it from the internal power
> add
> > a resistor and cap powered by a external switching wallwort in the 1 watt
> > range. Brand new meanwell  units are $11. These are medical grade not
> that
> > its required. The resistor is about 470 ohms a 1/4 watt. Dropping 24V to
> > 19V. Use a 470 uf cap on the side of the resistor connected to the 3500V
> > supply. Ground the negative to the chassis so the I pump meter works.
> > Taking this approach drops power consumption to .31 Watts. Larger higher
> > current supplies will draw higher power wasting idle currents.
> > I was going to drill out a hole and mount a small powerjax. But just
> really
> > didn't so brought out a pigtail to a powerjax. No change to the chassis.
> >
> > Operating this way the 3500V supply is always running. When I want the CS
> > to run I plug the original power cord in. After the ovens warm up in
> > business. No waiting for the ion pump to do its job and the best benefit
> No
> > crud burst as the tube is clean.
> >
> > The same adapter will easily power many 3500 V supplies. I have 3 5061s
> > that will be modified. Good news each 5061 consumes about 10 ma.
> >
> > Lastly 5061s do make noise around 2 KHz somewhat annoying.
> > Its easy enough to use a wall time and run just at night and switch the
> > supply on when actually using the Cesium. But a timer just multiplied
> power
> > consumption a lot.
> > A greener HP 5061.... Did I just say that. Sorry.
> > Regards
> > Paul
> > WB8TSL
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