CTC-4 Director 21

[Hagstar]

I wasted a lot of time on my CTC-4 thinking Hickok tested meant something. Indeed failure to work as a chroma amp or intermittent shorts weren't always detected. Tubes are cheap enough, and those 6U8s and AZs are considered expendable under such heavy use. I just order NOS (usually Sylvania or GE) for all critical tubes for any color set so old and keep the old ones for emergency/if they work spares.