Update:
So the retail price of a entry-level commercial GPSDO starts at around 600USD, which with currency conversion, freight and local taxes is way more than I want to spend on it.
The ebay ones, upon a lot of internet reading, seem to actually be quite good, so I have one of those on its way.
It outputs ~+13dBm and has a sinewave output.
I expect that is a little too much for the input on the SA44B (it’s at home so I cannot look at its back)?
Also does this prefer a sine or square signal?