I contacted Teseq UK a few hours ago, and they sent me the manual immediately.
Excellent service!
With the manual I figured out why the user interface behaved as it did.
Some options depend on which PNW is used.
I did not understand that.
My current issue now is to figure out why the open circuit output voltage
is half of what is chosen on the user interface.
With a load of 2.4K it drops to about half again,
and the pulse length shortens, from a previously OK waveform.
I get the feeling there might be something wrong with the output stage,
like a high output impedance, or a bad capacitor bank switch.
A high power device like this should be able to drive most anything and still maintain its output.
Or am I making a simple/stupid mistake here?