David,
I have a (recently purchased) 750A as well, but haven't used it yet. I have
the same problem with the batteries. I found this post in the archives from
2012:
On 11/22/2012 7:49 AM, Steve Smith wrote:
<snip>> Regarding the 750A batteries:
I replaced mine with four ER14250/LS14250 1/2AA 3.6V 1200mAh lithium
cells. Remove the original mercury battery holder and replace it with
a dual AA cell holder. Use the kind that has the batteries
side-by-side because you need to connect to the center tap between the
cells. Wiring is pretty much identical to the way the mercury battery
holder was wired. Install the lithium cells in a series string and you
have +/-7.2V which is a bit higher than the +/- 6.75V of the mercury
batteries but still works. The lithium cells have slightly more mAh
capacity than the mercury cells and a much longer shelf life which
works well for the 750A as the protection circuit draws very little
current. Don't disable this protection circuit, it's too easy to fry
the divider string if you're not paying attention.
Thanks - Steve
My guess is that the trip voltage will be changed a little bit, but not
enough to allow damage in case of overload. Sounds like a reasonable
solution
Cheers,
Dave M
David Garrido wrote:
Hello All,
I posted this over at the HP yahoo group as well, so pardon the
redundancy if you belong to both or more.
My new to me Fluke 750a reference divider arrived last evening and I
have been having one heck of a time finding info on replacement
battery options others have used on their 750a's. Fluke spec'd (2)
6.7v mercury cell batteries for the overload protection circuit and
these are clearly no longer available. What is everyone using for
power? I am hoping to not use a separate DC supply for this app.
The only manual I can find is here:
http://bama.edebris.com/manuals/fluke/750a/
<http://bama.edebris.com/manuals/fluke/750a/>
I have been able to find Wein batteries that are 1.35v zinc/air and I
could stack and shrink wrap 5 of those in series to arrive at 6.75
very stable volts, but they are a minimum of $4.50 each cell. I was
hoping to find a more affordable / elegant solution.
Will the circuit handle (2) 3.6v Li-Ion in series instead?
Any thoughts?
Cheers,
David
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