Hi Ed,
The output pulse is inhibited while the switch is rotating by?the pulse from?contact 4F on S1 (attenuator level) this feeds an RC network R18/C4 and Q2 on A7. If you turn the switch too fast the pulse is not generated. The pulse signal is narrower than the?coil circuit connection time due to differing contact widths.?Its explained in the service manual
Robert G8RPI.
