On the 3CX-6000A7 triode, the tube is 1st hi-pot tested between the
anode and grid (and a temp short between grid and cathode). Then the
polarity is reversed. Leakage should be < 5 ua in both cases. On a
3CX-6000A7, a good tube will hi pot test to 25 kv. (On a 3CX-3000A7, it
should hi-pot test to 20 kv. A good 3-500Z should hi-pot test to > 12
kv)
Then the tube is hi-pot tested between the grid and cathode (and a temp
short between the grid and anode). Then the polarity is reversed. A
good 3CX-6000A7 should hi-pot test to 5 kv (same 5 kv with the smaller
3CX-3000A7).The hi-pot tester has to be a DC type...and also incorporate
current limiting. It's an invaluable tool. It's also used to test vac
caps, (fixed and variable, glass and ceramic), vac relays, connectors, disc
caps, doorknob caps, and coax connectors, and also cables...and anything
else you can think of. It just saves a lot of grief..... knowing that the
parts you installed meet spec.
(I use the small, compact hi-pot tester sold by Tom Rauch, W8JI, through
his business, CTR engineering. It's a 0-15 kv DC unit, and incorporates
dual current limiting. It operates on anything from 12-18 vdc. That
comes in handy for a hamfest, etc. The unit also has a red led on it to
depict leakage current. I use a Fluke 87 DVM, in series with the return
leg, for a more accurate reading of leakage current. Both methods work).
https://www.youtube.com/watch?v=93kUcNIaps0
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