[volt-nuts] Fluke 732B

[Joseph Gray]

Bill,

With six 732B's, you certainly qualify as a volt nut.

Joe Gray
W5JG
 On Aug 20, 2013 10:37 AM, "Bill Gold" <wpgold3637 at att.net> wrote:

> Joe:
>
>     The 731A and 731B were run at room temp and therefore were subject to
> room variations.  They both use the same "Reference Amplifier" as the 732A
> & B use.  I have one 731B and it is amazingly stable for the room temp
> variations I experience at home.  When I was working we had a 731B that was
> also very good.  I had sent it for calibration over a 10 year period and
> the drift was equal to, or better than the 732 series.  At the end of the
> 10 years it was absolutely stable at less than 1 ppm.  This was all being
> done at a Fluke Service Center that was located in Milpitas California, and
> their 732As were being routinely sent to Fluke in Everett WA.
>
>     The difference between the 731 & 732 is that starting with the 732A
> all of the temperature sensitive components were enclosed in a oven
> assembly that had heaters surrounding the oven enclosure which is running
> at 45 degrees C.  This includes all of the resistors and adjustment pots.
>  I have torn down a 732A to the oven assembly and gone inside the assembly
> to replace a component.  It is a real trick to do this, but by being
> careful it can be done.
>
>     The fact that the 732As have been in operation for a much longer
> period of time probably explains the lower drift rates than the 732Bs.  The
> 732As have been "aged" much longer.  I know people who prefer the 732A over
> the 732B because of this.  The only problem with the 732A is that the
> heaters use more power than the 732Bs.  Early manuals spec 24 hour battery
> operation, but later manuals have changed that to 12 hours.  All of the
> 732As I have observed will only run for about 12 to 15 hours before the "in
> cal" light goes out meaning that the batteries have dropped below about 22
> volts.  The 732B is speced at 72 hours battery operation but I have no
> experience if this is true.
>
>     I guess I am a real "Volt-Nut" in that I have 6 732As at home right
> now.  I inter-compare them once a week.  The last time I was able to verify
> what the official "volt" is was in 2005.  Right now I need to find a good
> Cal Lab in the South SF Bay Area where I can have one of them "certified"
> against their traceable standards.  The Fluke service center was closed
> years ago.
>
> Bill
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