|
Hi, Refering to the Sylvania pamphlet "Color Fidelity For Older Receivers", the procedure is given for replacing CY's and AX's with rare earth 21FBP22 tubes. The CY requires a change in the drive to the red grid to eliminate pink highlights, but the AX conversion has no circuit changes noted in the text. Haven't done a metal to glass swap yet, but have done a few CY to FB swaps. My CTC-7B has original drive circuitry, and looks good to me.
I wouldn't change anything in a 4 unless it doesn't look right after the swap.
Kevin
__________________
stromberg6
|