Restoring GR 1120-AB Frequency Standard
phil wrote:
Russ
Do you have a photo, would it be possible to build? I have a few flasks of
mercury and a few 10's of thousands of mercury wetted relays that some could
be cannibalized for electrodes. The trick here is how thin is that column of
mercury. My guess the thinner the column, the finer the resolution or the
more it will travel with a small temp swing. Better yet, possible to cut
that thing open and fix it.
I know that's more time than it's worth.
Another thought, if the contacts have corroded in the mercury, perhaps from
contamination, would it be possible to "burn" the contamination off.
Thinking of excessive voltage/current. Perhaps making it arc internally.
Trick would be to limit current not to explode the thing, perhaps using a
charged capacitor. Just a thought.
Oh, do you have the whole rack, all dividers and the clock? I bet the old
clock alone is worth a thousand bucks today. Seems like it was driven by 1
KC. My old standard was complete, a 5 or 6 foot rack and came out of an old
Hamerland Radio plant.
phil
Phil
NBS used platinum wires in their mercury toluene thermoregulators.
These were constructed from pyrex as it proved more stable than
stainless steel.
These themoregulators had a sensitivity of about 0.001C and were used to
regulate the temperature of oil baths,
Bruce
Bruce, what was the diameter or how was the column situated to give those
resolutions.
----- Original Message -----
From: "Bruce Griffiths" bruce.griffiths@xtra.co.nz
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Wednesday, August 20, 2008 6:19 AM
Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
phil wrote:
Russ
Do you have a photo, would it be possible to build? I have a few flasks
of
mercury and a few 10's of thousands of mercury wetted relays that some
could
be cannibalized for electrodes. The trick here is how thin is that column
of
mercury. My guess the thinner the column, the finer the resolution or the
more it will travel with a small temp swing. Better yet, possible to cut
that thing open and fix it.
I know that's more time than it's worth.
Another thought, if the contacts have corroded in the mercury, perhaps
from
contamination, would it be possible to "burn" the contamination off.
Thinking of excessive voltage/current. Perhaps making it arc internally.
Trick would be to limit current not to explode the thing, perhaps using a
charged capacitor. Just a thought.
Oh, do you have the whole rack, all dividers and the clock? I bet the old
clock alone is worth a thousand bucks today. Seems like it was driven by
1
KC. My old standard was complete, a 5 or 6 foot rack and came out of an
old
Hamerland Radio plant.
phil
Phil
NBS used platinum wires in their mercury toluene thermoregulators.
These were constructed from pyrex as it proved more stable than
stainless steel.
These themoregulators had a sensitivity of about 0.001C and were used to
regulate the temperature of oil baths,
Bruce
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phil wrote:
Bruce, what was the diameter or how was the column situated to give those
resolutions.
Phil
The thermoregulator consisted of a horizontal ring tube filled with
toluene connected to a 13" long J -tube filled with mercury and
containing a capillary section at the top.
The top contact consisted of platinum wire within and parallel to the
capillary section, the mercury entered the capillary section and made
contact with the tip of the vertical platinum wire therein.
The other contact was made via a piece of platinum wire sealed through
the side of the glass tube below the capillary section.
Thus the top contact platinum wire fine enough to fit within the
capillary section of the J tube and to a first approximation the
diameter has no effect on the sensitivity which is due to the relatively
high thermal expansion of the (highly flammable and somewhat toxic)
toluene.
Platinum and iron have the advantage that they do not directly form
amalgams on contact with mercury and are thus not embrittled by
amalgamation.
However amalgams of platinum and iron can be formed electrochemically.
I have a couple of illustrations of such thermoregulators which I can
scan if you wish.
Bruce
Bruce,
nuf said, in that case it's the expansion of toluene, not the mercury. Can
easily see how that would work, actually rather ingenious. As always, more
than one way to do something.
Thanks, Phil
----- Original Message -----
From: "Bruce Griffiths" bruce.griffiths@xtra.co.nz
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Wednesday, August 20, 2008 7:05 AM
Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard
phil wrote:
Bruce, what was the diameter or how was the column situated to give those
resolutions.
Phil
The thermoregulator consisted of a horizontal ring tube filled with
toluene connected to a 13" long J -tube filled with mercury and
containing a capillary section at the top.
The top contact consisted of platinum wire within and parallel to the
capillary section, the mercury entered the capillary section and made
contact with the tip of the vertical platinum wire therein.
The other contact was made via a piece of platinum wire sealed through
the side of the glass tube below the capillary section.
Thus the top contact platinum wire fine enough to fit within the
capillary section of the J tube and to a first approximation the
diameter has no effect on the sensitivity which is due to the relatively
high thermal expansion of the (highly flammable and somewhat toxic)
toluene.
Platinum and iron have the advantage that they do not directly form
amalgams on contact with mercury and are thus not embrittled by
amalgamation.
However amalgams of platinum and iron can be formed electrochemically.
I have a couple of illustrations of such thermoregulators which I can
scan if you wish.
Bruce
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.