[time-nuts] Lucent KS-24361 GPSDO arrived today several questions

Bob Camp kb8tq at n1k.org
Thu Nov 6 07:04:43 EST 2014


> On Nov 6, 2014, at 3:44 AM, GandalfG8--- via time-nuts <time-nuts at febo.com> wrote:
> Hi Paul
> Prime question is what are you calling the "slave" unit?

1) Slave in the sense that it’s slaved to the GPS in the other box. Unless we find a serial link from the Ref-0 back into the Ref-1, that’s all it’s doing.
2) It fires up and the Ref-1 box gets all organized and locked up. It goes “ok” first, then the Ref-0 goes “ok” (locks to GPS). In that sense, the Ref-1 is the master.

My guess is that they default to output from the Ref-0 rather than Ref-1 because it’s the one more likely to fail (more single points to go wrong). 

> In normal use Lucent treats the Ref-0 unit as the master and Ref-1 as the  
> slave, but it's Ref-1 that contains the GPS module. Bit confusing

Yes it is confusing - sorry about that

> but if 
> you've  got Ref-1 with the GPS module then you're in business:-)
> It's turned out the transistor delay circuit isn't needed after all and the 
> wiring can be simplified too.
> All that's necessary to run the Ref-1 stand alone is to ground pins 2 and 3 
> on the J5 interface connector and there's a couple of convenient ground 
> pins  already on that connector, 8 and 13.
> In normal use pin3 is tied hard to ground, presumably via direct link from  
> the other module, so that can just be a wire link to either pin 8 or 13.
> Pin 2 is normally held at a logic low level so although a direct  ground 
> seems to work ok for that too, and no damage noted so far, I prefer to  play 
> it safe and ground that one to the other ground pin via a 470ohm resistor,  
> which also works fine.
> That's it.

So a single 15 pin connector with one jumper and one resistor (or jumper) plugged into the interface socket.

> The LEDS should flash at start up, followed by "No GPS" and "Fault" on  
> solid whilst the unit goes through acquisition and lock, this can take  an hour 
> or so, and then those LEDs should go off and the "On" light should  be 
> solid.
> At this point the 15MHz and 1PPS outputs are enabled.
> The J8 diagnostics connector is enabled from start up and SatStat can  be 
> used to monitor progress.
> The RS422 3 wire fudge suggested by Stu Cobb works fine for me, J8 pin 7 to 
> PC 9 way comm port pin 5, J8 pin 8 to comm port pin 3, J8 pin 9 to comm 
> port pin  2.

Works, but if you have an old style +/- 12 V RS-232 signal, things might or might not work forever. A lot depends on how they have protected the chips. They expect a 1.5 to 3.5V signal on the input, so even +/-5 is a bit exciting. Full blown RS-422 interfaces are sub $15 gizmos.


> Regards
> Nigel
> In a message dated 06/11/2014 01:24:33 GMT Standard Time,  
> paulswedb at gmail.com writes:
> I have  been following the threads on the KS-24361 some of the longest I
> have ever  seen on time nuts.
> So I have a very basic question.
> There was a 2  transistor delay circuit by Arthur way back. I believe this
> is  needed.
> But then the pin numbers seem to get a bit mixed up and there are  some
> jumpers with several comments.
> Is there a clear guidance on what to  do? I do not have the slave unit.
> Power is not an issue.
> Thanks in  advance for your help.
> Must say the units very  nice.
> Regards
> Paul
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