[AMPS] Zener screen supplies

[John Nelson]

Message text written by measures

>Two needed dimensions are left out. I would reach for my machinist's
scale. <

Indeed. But you originally stated:

>By subtracting, the length of the anode insulator may be arrived at. <

which is incorrect. 

The external anode-screen insulator in a small 4CX has a path length of
about 7mm. Flashovers can and do occur across it. I have seen several
4CX250Bs removed from distributed-amplifier service where tracking marks
have been clearly visible across the anode-screen insulator, suggesting
that the flashover has been external. I do not know whether that is the
predominant mode of anode-screen flashover in these valves. However, as far
as power-supply protection is concerned, it makes no difference whether the
flashover is internal or external. Both appear to be possible. 

73 John
GW4FRX

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