As I said, there's a long history of Afterglow and Paraglow and Paraglow II circuits; none of them are my designs though they are the basis for the current Paramount 2A3 circuit. One of the big changes was the power supply voltage, which increase when we went to the PGP8 power transformer. That meant the 2A3 cathode voltage had to rise, and therefor the cathode resistor had to dissipate a lot more power. It also meant the voltage rating on the cathode resistor became more marginal. I believe we have seen a few incidents where various problems with the driver would raise the direct coupled 2A3 grid voltage so high that the cathode bypass capacitor was damaged. That's why the Paramount uses a 450v rated part, even though in normal operation the voltage is half that.