I put a 2.7R 3W wirewound resistor right up against the anode tag; no ferrite.
The ferrites went on behind the grid stopper as detailed below
I also grounded the heater centre tap tag on the 13E1 socket too. Noise was reduced further.Cressy Snr wrote: ↑Mon Jun 03, 2019 10:00 pmOK
So what I did is this:
Grid stopper up against tag as normal
ferrite placed on grid feed wire
feed wire soldered to other end of resistor as close to resistor body as possible
any protruding wire cut off with flush cutting pliers.
Ferrite slid up wire until it is as close to resistor body as possible with a kink to keep it from sliding back along wire.
Resistor and ferrite end up at 90 degrees to each other
Result!
If you are using one 25V transformer heater winding per valve, ground the centre tap socket tag on each valve. If you are only using 1 heater winding, to feed both valves, only ground the centre tap tag on one of the 13E1.