6BK4 versus 6BK4A

[John Folsom]

The 6BK4s had a higher plate voltage and powere idssipation than the 6BD4. The X-rays produced by the HV regulator were proportional to the magnitude of the high voltage. In the 20-25KV range, the X-rays are pretty soft, and are absorbed by the metal HV cage, the cabinet, and the safety glass in front of the cRT (which also produces X-rays). As Charles stated earlier, the only danger might come from very prolonged exposure to an unshielded regulator or CRT ave very close range. Just don't sleep wit under your pillow while it is operating!