Re: Modifying W Plugin to use 6DJ8 Tubes
In post #108873 (https://groups.io/g/TekScopes/message/108873), David Hess suggested wiring 6DJ8's in parallel and running them off 6.3VAC from pin 13-14.
Unfortunately, that's out. Pin 13-14 is elevated to +100V and that will exceed the heater to cathode voltage rating on V124.
To recap, today I see exactly two approaches.
One, reverse a transformer. Unless you get lucky and find one with 6V and 18V windings like the 1A4's 120-0481-00, you have to wind your own, or put up with wire sized for 110V, i.e., at least 20VA even though the load is less than 4W.
Two, run a switching power supply off +225V. I will investigate this if the 12AT7 sub fails.