[Phil G4SPZ]

I would appreciate any advice from the Forum valve experts on two questions that have been exercising my own and my friend Phil's minds for a week or so.

Q1 - why did the ECL80 have a common cathode? My understanding is that the ECL80 was developed primarily as a combined TV frame oscillator and output valve in a single envelope, and the established late-1940s TV frame circuit practice used a separate triode and tetrode with their cathodes coupled together to improve linearity. Hence it made sense to use a common cathode from the start, and may have saved heater power too.

Q2 - why did Mullard/Philips bring the suppressor grid out on its own separate pin? All the circuits I have seen show G3 wired to the cathode anyway. Were there any applications that involved using G3 in other ways?

All thoughts welcome!