[time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...
GandalfG8 at aol.com
GandalfG8 at aol.com
Sat Nov 1 13:14:08 EDT 2014
I've confirmed from the model number that the GPS module on these is indeed
an Oncore UT+.
There's a Synergy engineering note available regarding Oncore battery
backup, and one place a copy can be found is here...
If so desired, it would be possible to retrospectively convert the UT+ on
the Z3811A to take the usual rechargeable battery but the precautions
mentioned in the engineering note would need to be implemented.
I'm running file checks on my archives right now so can't confirm exactly
what's involved, but I think there's one zero ohm SMD chip to be removed at
least, and fitting a battery can of course bring its own issues.
If anyone's interested, I've just uploaded some detailed photos of the of
RFTG-U Ref-1 circuit board to Didier's manuals site.
Probably far more detail there than even the nuttiest of us might consider
to be sane or healthy but I've got it apart anyway so what the heck....
and they might come in very useful if it decides to self destruct whilst
I'm poking it about on the bench:-)
In a message dated 01/11/2014 06:20:00 GMT Standard Time, bob at evoria.net
Hi Bob et al,
I don't understand the direction this question about the supercap has
taken. It's connected to pin 1 of the GPS receiver. It looks to be a UT+, so
that's the battery backup power. According to my UT+ manual the current
draw on this pin is between 5uA (at 2.5V) and 100uA (at 5V)? How many hours
will a .022F supercap keep at least 2.5V at that sort of discharge rate?
Unless the cap has gone bad, it seems more likely that Bob's comment about
it doing a fast survey and then doing a slower one in the background
probably has merit. In fact, my unit goes through its survey mode pretty quickly
on power up. So do those current/voltage figures imply several hours on
From: Bob Camp <kb8tq at n1k.org>
To: Discussion of precise time and frequency measurement
<time-nuts at febo.com>
Sent: Friday, October 31, 2014 9:22 PM
Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A,
Z3811A, Z3812A GPSDO system
I sort of doubt that a GPS aux supply is quite that low current. I have
seen some RTC’s that won’t last a month on a coin cell. My recollection is
that the Oncore backup is closer to that category than the “many years on a
> On Oct 31, 2014, at 9:26 PM, Brooke Clarke <brooke at pacific.net> wrote:
> Hi Bob:
> When HP came out with the 300 series Rocky Mountain Basic computers they
were fitted with a super cap to power the RTC.
> I will keep time for some months.
> Mail_Attachment --
> Have Fun,
> Brooke Clarke
> Bob Camp wrote:
>> The ultra cap is a pretty small one (physical small). You might be able
to find a larger (more farads) one that would fit in the same space. It’s
not going to help for a hours and hours sort of outage. It might get you
from dying in 15 minutes to dying in a half hour.
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
and follow the instructions there.
More information about the time-nuts