@gorgon53 - I have a simple question for you (since you've failed to answer the previous); what is a "reactive load"?
what do you think a 1:1 winding at, say, 10mA will look at the following grid?
It's obvious for me that your experience with xfmrs was painfull, I understand, there is hope!
In case you really do not know, the reactive load a transformer presents to the tube, or tubes, will consist of all the reactive components of the transformer itself, plus the transformed reactive components of the load the transformer feeds. At the low frequency end inductance, at the high end capacitance.
Both L as well as C are reactive, in themself they produce phaseshift and demand, additional to the resistive loadpart, current from the driving tube.
The rest of your question is a bit unclear, but i will answer what i thinck you ment. The following grid is the driven part, without grid current it presents ideally only a capacitive reactive load that is depending on the driven tubes and theyr operation conditions. This appearend capacitiv load will appear, as i allready mentioned, transformed at the primaries, as part of the load that the phaseinverter sees.
Your case, 1:1 pp, with properly winding arrangement and properly wound (ideally bifilar) is about the easiest to get wide bw and tigth coupling beween primary and secundary. Primary : primary coupling less so. Is 10mA enough?
Most likely it is at enough at audio frequencies, unless you are driving some bank of high mu paralled triodes. as long as your inverter stays in a sensible class A operation range and the the transformer is wound properly. Your measurements look very good, so i guess it is enough. If i remember correctly, it was 45 who said at 7mA operation shifts into class B, if thats so, he also proposed the correct cure. I have no idea on what 45 based his conclusion, as i did see only a 1:1 pp transformer without any other info than 100k resistive loading, or did i miss something?
As to your "its obvious...." i very much suspects that you came to your conclusion because you are a comparable younger guy, that overconfident still climbs the mountain...
Some day you will hopefully reach the top, slide down the other side and reach the valley, till then, all the best on your way to get the over 60years of the vast varyity of expiriences i have, especially regarding transformers.
And, yes, i have not much expirience in WINDING audio transformers, other than a few in my youth when winding your own transformers was still a natural part of DIY.
Now, its over 4am here, i just glanzed through the thread to see what happend after the last time i was here. Some attitudes towards what i wrote, whilst trying to be helpful, pissed me off a bit.
Despite of that, i need some sleep now, am over 76...