Stan I don't own a 5071. It sounds like you really did score a heck of a
nice piece of gear.
With respect to the batteries if original are available thats the way to
go. You should have the make and model number on the batteries.
If not then I firmly believe the same shape, AH, and size SLA will work.
Also I seem to remember you could connect an external battery. I had a 5071
here for 3 months a number of years ago. If substituting a battery the new
ones typically have the float voltage stamped on them or in the spec sheet.
Just check that the 5071 is operating at the right voltage. To low and
never fully charges. To high and you heat the battery. Both issues shorten
life and available current.
Congrats
Paul
WB8TSL

On Wed, May 10, 2023 at 8:58 PM Stan via time-nuts time-nuts@lists.febo.com
wrote:

On 5/10/2023 5:31 PM, Stan via time-nuts wrote:

I have had enough bad luck with PowerSonic batteries that I no longer
buy them.  (In a UPS setting, they failed in under 6 months' time of
mild use, and the dealer was Useless on RMA.  I did not weigh the first
set of batteries, but the 2nd set were all under-weight.)  I have had
MUCH better luck with RainGroup batteries.  Maybe consider:

https://www.raiongroup.com/12v-2-3ah-rechargeable-sla-battery-with-agm-technology/

H

--
Harlan Stenn stenn@ntp.org, part of
http://networktimefoundation.org - be a member!

Hi Stan,

Well, that's the deal of a lifetime. Congratulations.

1. Send us a copy of the readings. But mostly realize that the 5071A has
   a lot of internal operational integrity checks so if anything is out of
   order it will be the first to tell you. If the green LED is on you're
   good to go.

You can grab a digital summary of the readings by sending the
syst:print? command via the rs232 port. It looks something like this:

Freq Offset:          0e-15  Osc. control:     -6.14 %
RF amplitude 1:    27.9 %    RF amplitude 2:    26.3 %
Zeeman Freq:      39949 Hz   C-field curr:    12.170 mA
E-multiplier:      1318 V    Signal Gain:       14.4 %

CBT Oven:           5.7 V    CBT Oven Err:      0.04 C
Osc. Oven:         -8.9 V    Ion Pump:           0.4 uA
HW Ionizer:         1.0 V    Mass spec:         11.9 V
SAW Tuning:         1.0 V    DRO Tuning:         5.6 V
87MHz PLL:          0.9 V    uP Clock PLL:       2.6 V
+12V supply:       12.3 V    -12V supply:      -12.2 V
+5V  supply:        5.5 V    Thermometer:       43.5 C

You can also get some additional diagnostic information by setting the
logging mode to verbose and then watch the rs232 port during the
power-up self-diagnostic and warm-up process.

2. There's no usage or life counter in the tube or the instrument so
   there's no obvious way to know if the tube is new or used, or if used
   once a year, or once a month, or continuously. The 10890A (standard
   performance) tube can last decades; the 10891A (high-performance) tube
   usually gets 7 years if used 24x7x365.

If you plan to run the standard continuously then pay attention to the
operating parameters by, say, logging them once an hour. Decline in
short-term ADEV or rise in E/M voltage are the usual warning signs of EOL.

3. My recommendation is not to use the internal batteries. They are just
   a point of failure and decay. The 5071A already takes 120 VAC and/or 24
   VDC from the rear so there's glitch-free power redundancy. I usually
   supply 24 VDC from both a lab p.s. and backup batteries using a diode-OR.

If you really must use the internal batteries, last I checked you an
still buy the 12V modules pre-assembled. Alternatively you can refurbish
the ones you have. Each battery module contains six Hawker / Gates /
Enersys 2.5 Ah Cyclon batteries. Personally, given the value of a 5071A
(or especially its 10890A tube), I would not substitute with a random
SLA you have lying around. The Cyclon batteries are another level of
reliability.

A DIY repair of the battery modules is possible. A spot welder is the
right way but soldering works too. See page 57 of:

http://leapsecond.com/ptti2020/2020-PTTI-tvb-Atomic-Timekeeping-Hobby.pdf

4. Yes, the hp strap fits that standard sized frame no problem but I've
   never seen someone use it because 5071A are so heavy (75 lbs). I don't
   even like to use the rack mount ears but instead just place the
   instrument on a shelf. The alternative mounting is...

http://leapsecond.com/pages/atomic-bill/

/tvb

On 5/10/2023 5:31 PM, Stan via time-nuts wrote:

The handles are an artifact of the HP series II cabinet all the side panels
are fitted with handle mounts.

On Wed, May 10, 2023 at 11:47 PM paul swed via time-nuts <
time-nuts@lists.febo.com> wrote: