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

GandalfG8 at aol.com GandalfG8 at aol.com
Thu Nov 6 07:52:51 EST 2014

Hi Bob
I view the master/slave situation the same way you do, but only  commented 
because Lucent effectively sets things up the other way round so just  
wanted to be sure which way Paul was considering it.
As regards, the "faking", yes, a single 15 way plug containing just  a link 
and a resistor is exactly what I use now.
I realise the RS422 fudge isn't ideal but certainly very handy for some  
quick tests.
I've got two or three RS422 PCI interfaces but hadn't previously had any  
spare slots, now I've got a couple of lovely Magma 13 way PCI expansion units 
 but need to hack them about so the ports are at the front.
Whoever decided rack mount PC kit should be built with all the  connections 
at the rear must have been really nuts, and it was too long ago  to use 
"corridors" of racks as a viable excuse, someone somewhere just fitted  ears to 
desk top style cases and left the rest of us to get on with  it..
One of the best things I ever did was to buy a pair of "back to front"  
rackmount PC cases with all ports and cards available at the front, trouble is  
now I want everything else to match, and most test gear has just the same  
All good fun, and certainly never a dull moment:-)
In a message dated 06/11/2014 12:04:47 GMT Standard Time, kb8tq at n1k.org  


> 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 
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 
> 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 
> 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 
> 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  
> it  safe and ground that one to the other ground pin via a 470ohm 
> 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  
> used to monitor progress.
> The RS422 3 wire fudge  suggested by Stu Cobb works fine for me, J8 pin 7 
> 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 
> 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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