[time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup
kb8tq at n1k.org
Sun Oct 26 13:17:28 UTC 2014
Probably an important question to ask - how much current does this sub-species of the Z series pull off of 24V?
My *guess* would be it pulls a couple of watts (say 6W) per box once the OCXO is warmed up. If so, that would be just under 1/4 A on the 28V supply and just over that as the battery crossed 24 V.
If you have the full dual box setup, that would be 1/2 A on battery. A 7A SLA would get you 14 hours of run time. At least around here, that’s a long (and unusual) outage. There’s nothing in the house (except the Honda generator) that will run that long in an outage. I’d be quite happy with a 1-2 AH setup that gives me 2 to 4 hours (or half that if my power estimates are bunk).
The 7AH’s are already dirt cheap. They make a ton of them. I’d save some money, but not a lot. The main thing I’d save would be space.
> On Oct 25, 2014, at 9:54 PM, Tom Miller <tmiller11147 at verizon.net> wrote:
> I really don't disagree with you. I did say run the supply at 28.0 and use a diode off the supply to the battery. That would place the float voltage at 27.3 or so. Best would be to follow the manufacturers float service recommendations. Ideally it should also be temperature compensated with a -2.4 mV/°C slope. Not a problem with how we use these in the lab though.
> And yes to get the longest run time, just power the main unit from the battery as Bob suggested.
> Now I am just waiting on some DB-9 connectors. I ran out of them and the local RatShak went TU.
> ----- Original Message ----- From: "Christopher Brown" <cbrown at woods.net>
> To: <time-nuts at febo.com>
> Sent: Saturday, October 25, 2014 5:32 PM
> Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup
>> Might want to dial that back a bit.
>> Since 12V/7ah batteries are mentioned I am assuming standard small
>> gelcell units.
>> Proper float voltage for a deep cycle is lower than a SLI type, and
>> gellcell even lower.
>> Generally 13.6 - 13.8 would be the gellcell range, with 13.6 being right
>> on for long life use of _small_ batteries. Equalizing charge wold be 14
>> - 14.2.
>> Floating a small gelcell at 13.6 (27.2) v.s. 14 can mean the diff
>> between 12 - 24 months v.s. 5 - 7 years service life.
>> On 10/25/14, 11:39 AM, Tom Miller wrote:
>>> These units are ideal for powering via a float charged lead acid battery.
>>> Use two 12 volt / 7 AH batteries in series and adjust the regulated float
>>> power supply to 28.0 volts. Be sure to use a diode from the supply to the
>>> battery just in case the supply can't be back fed during a power fail.
>>> ----- Original Message ----- From: "Bob Camp" <kb8tq at n1k.org>
>>> To: "Bob Stewart" <bob at evoria.net>
>>> Cc: "Time Nuts" <time-nuts at febo.com>
>>> Sent: Saturday, October 25, 2014 3:01 PM
>>> Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup
>>>> Spend the effort, get an antenna outside the house. Beg / borrow / steal a
>>>> UPS. Even a brand new one is less than you paid for the 3812.
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