Hi,
This is a basic, crude way to test the 4CX1000A, 4CX1500B for shorts, gassy, flashover.
Made the frame from some kind of Teflon or UHMWPE sheet.
Used an HP 6525A 4kv, current limited power supply for the plate
Used an HP 6521A 1kv, current limited power supply for the screen.
These power supplies can run into a dead short w/o damage and w/o overcurrent, good for test system usage.
They will also anchor a large boat against a strong current.
One of the 4CX1000A had not been used for decades.
Let the filament stay on for an hour, then brought the plate up to 800v.
Cooked that for another hour.
Brought the Screen up tp 100v.
Next, plate to 2kv
Screen to 150v
Let that run for a while, observed current draw on plate and screen.
Tested two (one old, one NOS) EIMAC 4CX1000A, and one NOS EIMAC 4CX1500B.
None drew excessive current or flashed over, so I am confident they would not damage an amp.
https://www.youtube.com/watch?v=zvw7E-9TzDI73
Frank
KJ4OLL