[time-nuts] Ublox Neo M8T no output on TP2 question, please?

[Ben Hall]

Good afternoon all,

Finally, a TimeNuts topic that I might be able to help with!  Usually I 
just sit back, read, and learn from the group because y'all are way over 
my head.  ;)

I've been playing around with the M8T for a couple of years now, both at 
work for professional applications and here at the house.  At work, 
we're using that second timepulse to timestamp data very accurately.

The M8T second timepulse (TP2) can indeed go from 0.25Hz to 10 MHz 
output.  See the last page of the product summary:

<https://www.u-blox.com/sites/default/files/products/documents/NEO-LEA-M8T_ProductSummary_%28UBX-16000801%29.pdf>

In fact, I've got an M8T right now putting out 10 MHz on TP2 with the HP 
5328A telling me it's right on 10 MHz.  :)  One of these days, I need to 
build a cable to hook up the OSC INPUT of the 5328A to the 10 MHz output 
of either the Z3801A or the TruePosition.  But, on the other hand, the 
internal OSC isn't that bad for what I need, it's about 5 Hz high at 10 
MHz when cold and that usually settles down to about 3 Hz high at 10 
MHz.  For hobby stuff, that's good enough!  ;)

Getting TP2 set up and working with uCenter (I'm using 8.28) takes a lot 
of fiddling.  I don't know why!  It should be so straight forward.  The 
best I can tell, there is something goofy going on when you try to set a 
frequency and a length with uCenter...but if you click Frequency and 
Duty Cycle it works.  Why, I don't know.  Here is a screen shot of my 
TP5 settings in uCenter that are working right now:

<http://www.kd5byb.net/M8T/m8t_2.jpg>

And here is it at 5 MHz:

<http://www.kd5byb.net/M8T/m8t_3.jpg>

And the counter confirms 5 MHz output.  :)  If I put it on the scope, 
it's a nice 50% duty square wave.

Try those settings.  If you still don't get an output on TP2, my 
thoughts are that you've either got a counterfeit module or something 
isn't right with it.

The NEO-M8T I've got is on a PCB of my own design...and was either 
bought direct from the uBlox or from Digikey / Mouser, I don't remember. 
   so there is a really high chance of it being genuine.  ;)

Thanks much,
ben