Tekron clocks do not store any time data in non-volatile memory. As such, every time the clock is power-cycled the clock will need to re-synchronize to a time source before it is able to transmit time on any of its outputs.
You will notice that during this initial synchronization process your clock's front panel will not show any time. This is because the clock does not have a source of time yet and therefore does not know the time.
01 January 1970 is the Unix time epoch, the earliest UTC date that Tekron clocks are aware of. It essentially corresponds to a time of "zero" in the clock's hardware. This is why the Configuration Tool shows this date prior to the clock synchronizing with a time source. If local time is behind UTC, then an earlier date (1969) will be shown.
If a clock is in holdover and a power cut occurs, the clock will not function as a time server until sufficient GNSS signals are available for it to synchronize to. For this reason, we suggest critical systems use an uninterruptible power supply (UPS) to power the master clock.