Battery backup of frequency standards
Hi Brooke,
No, I'm thinking of LiSO2. Early examples of the 5590 had what was
not so jokingly called a detonate lever on the top. When the lever
was acuated, a short was put on the cells, and after a suitable amount
of time, the battery would belch forth a great quantity of H2S gas. This
inerted the battery in a most dangerous and unpleasant way. Every wonder
why that lever was there? It's because the LiSO2 batteries are even less
safe when they still have some life left.
The Army guys out at Ft Monmouth have gone to great efforts to make
the LiSO2 battery safe, but I hear that one still goes off from time to
time. As a result, all military battery compartments that are used with the
LiSO2 batteries, are required to have a screened vent on the side to
handle a destructive blow off of H2S.
Notice that all of the applications you have mentioned are emergency in
nature, and not intended for the unwashed masses. You won't be finding
a LiSO2 battery for your laptop, or on the rack at Home Depot.... well,
you shouldn't.
-Chuck
Brooke Clarke wrote:
Hi Chuck:
I don't think it's possible with a BA-5590. There's circuitry inside
that limits the current draw with a dead short. Fully draining the
battery is no problem, in fact there's a one way action switch on the
BA-5590/U that puts a resistor across each internal battery in order to
fully drain it.
You may be thinking about Li-Ion or Li-poly batteries where fire comes
out of the battery when it's mistreated (too much current either charge
or discharge, over or under voltage, or mechanical puncture). Like the
video at: http://www.valence.com/SafetyVideo.asp
Not true about LiSO2 batteries and commercial products. The "D" cell
that's inside the BA-5590 is used in a number of products, medical
emergency equipment and head mounted flashlights come to mind.
Does any one still have a DC-468 that is keeping time and locked on? Mine
quit ages ago. It is a lot more than 50 ms off. - Thanks - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
I have several TEMEX LPFRS-01 Rubidiums with Trak GPS Disciplining Modules.
I have lots of data on the Temex, but none on the Trak. I even have the
interconnect cables between the Temex and the Trak, but that is as far as it
goes. There are two Trak units and two Temex units for full redundancy. The
Temex modules are mounted on a heatsink of their own and the I/O to the Trak
is my main problem. Essentially, I do not know what they are. Each of the
Trak modules has a part number of 4000696-001. They plug into a housing with
a mother board that has all of the other connectors on it for the GPS
interface. The part number of that unit is 48817-1000-101. Any suggestions
would be appreciated. Thanks - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
OK, guess I am on a roll this AM. Whiling writing my lost post I was
reconsidering one of my previous thoughts. What is the advantage of a GPS
disciplined Rubidium. I sure do not see any. Yes, for those times when there
is an outage of GPS, it may be handy, but the holdover time of a decent
ovenized oscillator in the short term is actually better than that of a
Rubidium, and if GPS is out for a long time, well, all bets are off anyway.
Of course in that case a rubidium would be a better timekeeper. So, like
everything else it seems to be a trade-off. I was thinking of taking one of
my Z3801s and placing a Rubidium in it in place of the ovenized oscillator.
The more I thought about it the more I decided it was not a worth while
effort. Any comments? - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
Does any one still have a DC-468 that is keeping time and locked on? Mine
quit ages ago. It is a lot more than 50 ms off. - Thanks - Mike
Mike,
Maybe you and I are the only ones with GOES
receivers still powered on?
After 30 years the GOES time service officially
went off the air on January 1. But it has been on
and off a few times since then (and with reduced
accuracy). My last signal lock was in April or
May, I think. I stopped logging at that point and
all my receivers have been blinking for a month.
Even if you don't get time lock, do you still get
RF lock and/or data lock on your 468-DC (the
two LED's inside)?
For good reading see :The GOES Time Code
Service, 1974-2004: A Retrospective"
http://nvl.nist.gov/pub/nistpubs/jres/110/2/j110-2lom.pdf
Tom -
I think you may be right since I remember the last time you asked a question
about this and I believe I was the only one that replied. Right now it is
not convenient for me to look inside as the 468 is on top of a tall
entertainment center in my office with some other junk on top of it. The
antenna is facing one of the windows. It may be easier for me to look at the
IF coming back down the coax to see if there is RF lock or not. I have a BNC
T on the rear of the 468 so it is easy to connect it to the SA and see the
downlink IF depending on which bird it is locked to. BTW, as I mentioned to
you some years ago the manual does have an error in one of the IF
frequencies. I do not remember if it is the east or the west. I guess it is
of little consequence now. I really like the large displays on the 468 and
would like a similar clock to replace it. Any ideas? - 40 years ago I would
have just built one, now it seems like too much trouble. - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Tom Van Baak
Sent: Saturday, June 11, 2005 10:59 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] DC-468
Does any one still have a DC-468 that is keeping time and locked on? Mine
quit ages ago. It is a lot more than 50 ms off. - Thanks - Mike
Mike,
Maybe you and I are the only ones with GOES
receivers still powered on?
After 30 years the GOES time service officially
went off the air on January 1. But it has been on
and off a few times since then (and with reduced
accuracy). My last signal lock was in April or
May, I think. I stopped logging at that point and
all my receivers have been blinking for a month.
Even if you don't get time lock, do you still get
RF lock and/or data lock on your 468-DC (the
two LED's inside)?
For good reading see :The GOES Time Code
Service, 1974-2004: A Retrospective"
http://nvl.nist.gov/pub/nistpubs/jres/110/2/j110-2lom.pdf
/tvb
http://www.LeapSecond.com
time-nuts mailing list
time-nuts@febo.com
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
My impression is the RF and subcode data lock
should still work; it's just the NIST timecode data
bits that are no longer valid (GOES itself is still
100% operational - all they did was stop sending
the NIST timecode and sat pos info).
Yes, the receivers make a very nice clock display,
and the IRIG, 1 PPS, or other outputs are useful.
Given the clean board layout, it should be quite
simple for someone to turn it into a stand-alone
clock; either by simulating the manchester code
that goes to the uC, or by piggy-backing on the
existing display drivers. There's hundreds of nice,
used GOES receivers out there so there might
be a market for someone with time on their hands
to develop such a retrofit gizmo.
One could, for example, make a black box that
takes a GPS NMEA and 1 PPS output and
converts it to something a 468-DC can lock on
to; either through the antenna input or directly
onto one of the test points on the board.
/tvb
----- Original Message -----
From: "Mike Feher" mfeher@eozinc.com
To: "'Tom Van Baak'" tvb@leapsecond.com; "'Discussion of precise time and
frequency measurement'" time-nuts@febo.com
Sent: Saturday, June 11, 2005 12:33
Subject: RE: [time-nuts] DC-468
Tom -
I think you may be right since I remember the last time you asked a question
about this and I believe I was the only one that replied. Right now it is
not convenient for me to look inside as the 468 is on top of a tall
entertainment center in my office with some other junk on top of it. The
antenna is facing one of the windows. It may be easier for me to look at the
IF coming back down the coax to see if there is RF lock or not. I have a BNC
T on the rear of the 468 so it is easy to connect it to the SA and see the
downlink IF depending on which bird it is locked to. BTW, as I mentioned to
you some years ago the manual does have an error in one of the IF
frequencies. I do not remember if it is the east or the west. I guess it is
of little consequence now. I really like the large displays on the 468 and
would like a similar clock to replace it. Any ideas? - 40 years ago I would
have just built one, now it seems like too much trouble. - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Tom Van Baak
Sent: Saturday, June 11, 2005 10:59 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] DC-468
Does any one still have a DC-468 that is keeping time and locked on? Mine
quit ages ago. It is a lot more than 50 ms off. - Thanks - Mike
Mike,
Maybe you and I are the only ones with GOES
receivers still powered on?
After 30 years the GOES time service officially
went off the air on January 1. But it has been on
and off a few times since then (and with reduced
accuracy). My last signal lock was in April or
May, I think. I stopped logging at that point and
all my receivers have been blinking for a month.
Even if you don't get time lock, do you still get
RF lock and/or data lock on your 468-DC (the
two LED's inside)?
For good reading see :The GOES Time Code
Service, 1974-2004: A Retrospective"
http://nvl.nist.gov/pub/nistpubs/jres/110/2/j110-2lom.pdf
As one of those who would not find it "quite simple"
I would offer two NIB DC-468 receivers, no down-
converters or manuals, for $35 each.
Of course, if someone has a GOES transmitter module for
a reasonable price (and a down-converter) then I might
be interested.
The basement is full of projects but my life-timer is
running out.
Bill Hawkins
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com]On
Behalf Of Tom Van Baak
Sent: Saturday, June 11, 2005 3:39 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] DC-468
Given the clean board layout, it should be quite
simple for someone to turn it into a stand-alone
clock; either by simulating the manchester code
that goes to the uC, or by piggy-backing on the
existing display drivers. There's hundreds of nice,
used GOES receivers out there so there might
be a market for someone with time on their hands
to develop such a retrofit gizmo.
Hello, Mike.
I tried to lock a FRS-C rubidium up to a Z3801A, in place of the HP10811
oscillator. I did not have much success, it ruined the short term and
long term stability of the rubidium. But, I'll say , I did not know
what I was doing - or I know better now.
I believe that the Z3801A GPS controller/DAC outputs a new value every
15 seconds - which may be too short of an update rate for a rubidium
oscillator.
To use the Z3801A, you would need either an amplifier or attenuator
network on the output of the DAC and it depends on the voltage
sensitivity of your rubidium. I can't find my notes, but I believe the
10811 oscillator was 1x10-7 or 1x10-9 for a 1 volt change. You will
also need a low tempco summing amp and some type of precision voltage
reference as you will need to "bias" your rubidium around the correct
frequency.
I have used Brook Shera's GPS controller to control the rubidium and it
performs well. It also needed an amp and precise reference. Brooks had
made several PICS (the present PIC uses a 60 second update rate) for my
applications and the last set of data shows 100 sec variances at
1x10-12, and 10,000 sec variances at 3x10-13.
Mike Feher wrote:
OK, guess I am on a roll this AM. Whiling writing my lost post I was
reconsidering one of my previous thoughts. What is the advantage of a GPS
disciplined Rubidium. I sure do not see any. Yes, for those times when there
is an outage of GPS, it may be handy, but the holdover time of a decent
ovenized oscillator in the short term is actually better than that of a
Rubidium, and if GPS is out for a long time, well, all bets are off anyway.
Of course in that case a rubidium would be a better timekeeper. So, like
everything else it seems to be a trade-off. I was thinking of taking one of
my Z3801s and placing a Rubidium in it in place of the ovenized oscillator.
The more I thought about it the more I decided it was not a worth while
effort. Any comments? - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
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