[time-nuts] LTE-Lite Plans

SAIDJACK at aol.com SAIDJACK at aol.com
Tue Nov 25 14:51:40 EST 2014

please remember you need proper lightning protection if you put the antenna 
In a message dated 11/25/2014 11:43:09 Pacific Standard Time,  jim at jtmil
ler.com writes:

I have  one of the LTE-Lite 20Mhz units and plan to use it as a frequency
reference  for my ham radio gear. My planned setup is as follows:

I'm putting it  in the recommended Hammond enclosure powered by a USB cable
from my PC. I  had originally planned to use the wall wart provided but I
want to get  status from the unit without hacking a window in the top to see
the LEDs so  I plan to use TBD software to provide a status check. I briefly
thought  about doing something with an Arduino and display shields but that
seemed  like too much work for now.

I'm using a inverting D FF from TI  (SN74aup1g80) as a divide by 2 to
provide 10Mhz. The chip and associated  passives will be on a little circuit
board mounted in the open area  normally reserved for the external
oscillator. The output of the chip will  be connected via a series resistor
of about 400 ohms to a SMA connector.  This resistor will limit the load on
the FF and the LTE-Lite power source.  Power will be taken from C6.

This output will only go a few inches to a  DEMI 10Mhz 4 way splitter The
input of the splitter will be equipped with  an additional ERA-2+ amplifier
(50 ohm input) which will restore the signal  levels lost due to the series
resistor in the LTE-Lite addon. The DEMI  splitter will also be equipped
with a manual power switch which will allow  me to kill the output of the
box if the GPSDO fails for some  reason.

The little hockey puck antenna will be mounted directly outside  the shack
wall near a south facing wall which will limit the visibility to  only half
the horizon. I'm assuming this will be enough for my modest  needs.

The four outputs will be used as follows:

One will go to  the K3 ExtREF to provide an external reference.

Two will go to separate  TX/RX converters for low frequency (<600Khz) use
and be used with the  transverter I/O on the K3.

The last will be used as a general  calibration reference.

When the power switch on the DEMI splitter is  turned off the K3 will revert
to using its internal TXCO.

I leave  the PC running 24/7 and the power to the LTE-Lite would only be
interrupted  when the PC is rebooted. I don't need a frequency reference
during the  reboot time since I always operate my rig with the PC on and
running. The  TBD status software will tell me when the LTE-Lite is synched
up again. The  PC is served by a UPS and the shack circuit is one which is
served by our  whole house generator.

I have the DEMI splitter built up and working.  Now just waiting on
enclosure from Digikey. I should have everything  running by mid December.

I still need to figure out what to use for the  status software. Ideally I'd
like an applet to display appropriate status  indications on my monitor for
now I'll examine the uBlox and Putty and if  not satisfactory perhaps I'll
write something in VB.

Feedback and  suggestions welcome.


Jim  ab3cv
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