Our friend Zygmunt Jerzyński returns in full power with the new article in his outer scape elaborated way. Red Anode GU80 test article invites in full red vibrancy.
I tried not to exceed the maximum spec limits, and almost succeeded ..
Started easy and gentle …
But after that cranked it up to the full spec limit of the tube.
I stopped the long term stress test at values:
1380 V Anode to Cathode,
0,325 A Cathode Current,
Totalling 448 Watts dissipation,
Plus the 140 Watts of filament heating.
{{ short term, on the picture above, it was even 0,4 A at -101V bias, but that was a tad too scary to maintain in the long run … }}
At full load, the power supply voltage sagged from 1700 V DC at idle, down to 1380 at full load (450W). Intriguing, as the transformers in th power supply are a dual set of 800VA toroids.
I managed to make readings of quite a few DC operating points during this session. These will be useful when connecting the push-pull transformer, as they give some insight as to the possible choice of operating point, and provide a verification of the “published” pdf specs, as compared to real life readings.
All tests were conducted in pentode mode, with close to maximum (+/-) allowable S2 Voltage of 600V.