Registered User wrote in
:

An alternative to rewiring the filaments is to build a power supply
using a 24 V transformer. My Q5-er supply uses back-to-back 25.2V
transformers to feed the rectifier/filter circuit. The filament
voltage is taken from between the two transformers. A 6.3-0-6.3V
transformer supplies 6 & 12 volts.

If I'm going to use the remote rotatble ferrite bar antenna (and I
definitely want to) I'm going to need 28 VAC 400 Hz. Does anybody know of a
schematic for an oscillator circuit? I looked online and couldn't find
anything.