[time-nuts] Oscilloquartz BVA has been sold. Thank you all who expressed an interest.

[Bob kb8tq]

Hi

How often do you loose power? If it’s once a year for < 1 hour …. how big an 
issue is this to you? Do you *need* to do precision measurements every day?
Is restarting a run once a year a major issue? Option one is to simply restart
after an outage. Option two is to protect against it. 

To protect a full bench setup, some sort of UPS is going to be needed. With counters
and all the other “stuff” there really is no other practical approach. That immediately
gets to how much power for how long. A bench that pulls 800W and a typical
outage of 4 hours is going to mean a pretty big battery pack on the UPS.

If you go shopping and expect a typical outage of 4 hours, shop for something rated
at 6 hours (at your power level). If the bench appears to pull 800W go for something
>= 1,200W continuous duty. For a variety of reasons, you need to have some “margin”
in both numbers. 

When you get into run time dimensioned in hours, things get nutty expensive. A generator 
(natural gas or propane powered) with an auto start is often the lower cost approach
compared to giant batteries. You still need the UPS, but it only has to run for a few 
minutes while the generator fires up. 

======

In the house before this one, the generator *was* the way to go. That neighborhood
was deep in the woods. If a big storm blew in off the ocean and a lot of trees went down,
our little cluster of houses was not very high on the list for repair. We could be out 
for a week or more every couple years. An outage of > 2 hours was pretty normal
several times a year. 

=====

When we first moved in here, the main feed line into town had “issues”. Just about 
any time of year, a modest amount of wind could shut down the feed line. It was 
reasonable to expect multiple outages a month. In the windy months multiple 
outages a day did happen. As a result, we had a *lot* of UPS’s scattered around
the house. The outages were mostly in the 5 seconds to two minutes range. Very
normal UPS units did the trick.

A convenient tornado came through a few years ago. It took out about 1/3 of the 
feed line and the sub-station feeding the line. As a result they replaced the entire
feed line. Since then, there has been very little need for the UPS fleet. 

One aspect of keeping a heavily used setup running is wear and tear on the batteries. 
They don’t last as long as you might hope they would, at least not to anywhere near
the full capacity rating. Going to LIthium’s instead of sealed lead acid’s might help
this, but at a pretty steep price up front. Are they cheaper long term? We’ll know in
20 years …. :)

Bob

> On Sep 25, 2020, at 12:27 AM, Bill Notfaded <notfaded1 at gmail.com> wrote:
> 
> I plan to keep BVA powered.  My question was how do you accomplish this and
> what do you do it with?  I've been using PS like for example Fluke
> PM2811, Tekpower TP3005T, Dr. Meter HY3005F-3 (these are similar), Sorensen
> and some older HP.  I've had good luck them all so far.  I'm curious if
> someone's found some better way that's smaller and newer and still good?
> It looks like a big UPS is in my future.  Luckily I rarely have power
> outages here even in the desert of the southwest in AZ where the temp and
> even humidity is mostly stable inside in the AC in summer and even heat in
> the winter.  It's dry in both cases inside in my lab.
> 
> Do you monitor the thermistor along with the frequency and external
> temperature/humidty?  I've been using this for external:
> 
> http://www.dogratian.com/products/index.php/menu-sensors/menu-usb-pa-type-a-bmp085
> 
> It seems to work pretty well to monitor temp and humidity with USB for the
> room plugged into my computer.
> 
> What I'm starting to think about is how do this on much larger scale at the
> same time?  I have a few counters 53131, 53132, CNT-90, and an SRS SR620
> but how do you do long term measurements over long extended periods on
> multiple powered up oscillators?  Is there a mass way to do this?  I know
> the computer could handle this with GPIB but is there another better way to
> say monitor all these variables on say 5 to 10 DUT constantly easier?  I
> have an HP3458A but I wouldn't want to keep it tied up too long.  The
> counters I run a lot so that's not a problem really.  What do you
> orchestrate the whole thing with?  I have labview NXG but I'm not sure some
> hardware DAQ or something with some scripts might not be better for
> multiple DUT than messing with labview running all the time.
> 
> How do you do it?  How do you get stats on multiple oscillators for years?
> I suppose some oscillators deserve their own dedicated counter 24*7 and
> maybe even a raspberry pi to sample the GPIB.  I do have a few USB to GPIB
> interfaces and Pi's are pretty cheap but I've only got a 2 and a 3 right
> now.  But then is there a timelab for Linux?
> 
> I suppose the first main key is to just keep all the OCXO and GPSDO's
> powered all the time first on a UPS?
> 
> Thanks,
> 
> Bill
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