(One more try to see it still throws most of my response and the attachment
away)

Marvin Posted

The length of what a Short term Time means is all relative to how long it
takes to do the Transfer test.

across the USA.
Several minutes would be a more typical case.

To do the TC test of the attached plot showing the "Zero TC" using one of
Geller's Modified AD587 Reference boards,
Short term stability was over a 24 hr period. Time to let the Temperature
change slowly AND more important is to check it on the way back for
repeatability.

The thing that seems to be skipped over a bit too lightly is to get the Best
reference for a Volt Nut, (or freq nut) no mater what you're using,
It is ALL about aging, grading and selecting the best from a bunch of them
and then making the best better, by matching or TCing or whatever.

What Geller's stuff did was allow me a Fast, Cheap, and Easy way to sort
thorough a  lot of stuff to make several and find the best ones.

WarrenS

[volt-nuts] Best reference after LTZ1000
Tue Aug 24 17:37:12 UTC 2010

Hello Charles,

Thanks for the links and the insight.  Sorry for delay, but was also
reviewing the old commentary on time-nuts about the Geller
references, his patents, and more on voltage standards not on this
lists' archives.

Overall though, the more important item is taken as a whole is this
box with the patented stabilizing circuit a better reference than
something else, assuming this is what your friend has?

I agree with your criticism of the circuit function.  See the
schematic on the patent.  There is a novel item, notice that the
supply voltage for the LM399 comes from the vref output of the AD587
op amp, rather than V+ as expected?  This provides an ultra stable
supply for the LM399, compared to one from a standard regulator or
battery, while also putting a continuous load on the op amp.  Not
sure what this does to the ppm/oC over time, so I would think Geller
should characterize such as effect better to capitalize on it.

Geller does offer the patented circuit on a stabler and more costly
version of SVR, but you have to ask him for it.  Its near $300
compared to the $35 SVR.

But I think there are more conventional ways to achieve stability
without the uncertainty of this circuit's function.

If others aren't aware, the Time Nuts archives around 2008/9 have
discussions about WarrenS's modification and his experience with
Geller boards and chips, mailed to-fro East and West coast USA, and
his experience with its stability.  There are other posts affirming
Geller and Malone's boards at least for short term stability as
transfer references, no time statement what short means, I presume at
minimum the time it takes to receive US mail from coast to coast.

Thanks a bunch again, for the leads and comments.

Hello WarrenS,

Time for me to leave for the night, but the image/graph came through,
and it is AWESOME!
This is what's needed.  More later, thanks a ton.

Also the point you emphasize is vital, voltage references are not
identical, some are more stable that others even within the same
model line.  Aging and grading is a key function, and very hands on,
which being labor extensive, translated to expen$ive, as we see in
the HP 3458a high precision option board.

At 07:10 PM 8/24/2010, WarrenS wrote:

veral and find the best ones.