question

@KCRtechy I cant comment on the frequency accuracy of your inverter, or why your clocks are synced to the mains frequency.

However every mobile phone will be locked to the cell tower time base and should be accurate to the second.

It would seem odd that your desk would not include a computer of some sort (?). You can increase the rate that the clock syncs to a internet referenced time. Include a clock widget on the monitor.

Why re engineer the wheel?

Far from attempting to "re-engineering the wheel" what we want is a reliable desk clock for a number of reasons one being that in a Community based radio station there are a wide range of people generally none of whom are fully trained Pro Presenters.

Amongst the cohort of Presenters are the incessant "fiddlers" who somehow find time to mess with settings particularly on the studio computers of which there are two and ONE has at the top of the screen the Internet clock which is deadly accurate. The keyboards were removed to prevent the mucking around but that has still NOT stopped some who manage to DELETE the on screen clock and then have no idea as to how to restore it.

Thus the next Presenter settles into a desk that when powered up has NO screen clock. So then it is HELP !!

The inbuilt desk clocks are synced to the 50Hz supply and also can be free running controlled by a crystal in the clock module but that GAINS time so I opted for the 50Hz sync signal. These desks are over 10 years old and have recently been taken out of storage and installed in new studios and the layout is top rate as the digital clock sits right over the desk VU Meters so when they are sitting there Cued up waiting for the News feed to start they are looking at the clock AND the Cue VU Meter and a finger on the Fader ON button so its an instant switch to the feed.

But the computer screens sit above the desk again and that clock is well out of view in keeping an eye on what they are doing on the desk as they have to switch the news on and quickly fade whatever they are currently playing to air as the intro runs through.

Operationally the Desk Clock is the best one to use.

I am still scratching my head as to why a top rate product such as the Victron inverter is unable to supply a precise 50Hz supply and a cheap Chinese one could.

Syncing a clock to mains frequency is still a thing?!

Do you get 50Hz from the inverter if there are no loads connected? Try disconnecting all loads from the inverter and then testing the frequency at the terminals. Some loads can mess with the frequency.

If the frequency is still wrong without loads I would contact the dealer from whom you bought the unit for RMA.