[time-nuts] LTE-Lite Plans

paul swed paulswedb at gmail.com
Tue Nov 25 14:52:02 EST 2014

Because of the short runs you should be quite fine with your approach. I
used the 74HC version to do my dividing using the second section to get 5
MHz. Lots of gear still uses that.
Frankly ublox and such don't show you much and I am using PUTTY.
There is another pgm from India but shows much the same as ublox.
They do show more if NEMA. But what we want typically is the status.
So the suggestion of VB is very reasonable to create a more useful
That is mostly watching the frequency offset and such in the status message.
I sure all that can be dressed up easily and nicely.

On Tue, Nov 25, 2014 at 2:42 PM, Jim Miller <jim at jtmiller.com> wrote:

> 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.
> 73
> Jim ab3cv
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