A Dedicated Interface … (/cont)

The 1MHz Cathode-Follower buffers …

‘Borrowed’ from the RA218 …


V2 and V3 are 12AT7s. Only half the circuitry is shown on the left since both halves are identical.


The PSU … Keep it simple!

Although this configuration of full-wave rectifier imposes a higher load on the transformer, the actual load is very small, resulting in negligible effect. I found the transformer in my ‘junk box’ and found it to be extremely ‘generous’. Initial tests yielded 450V DC off load! … hence the inclusion of R1 (560R) and R3 (18K). R3 serves to provide a static load before the valves conduct during which time the maximum voltage at F2 is in the region of 265V. This drops to about 205V when the valves have reached their operating temperature.