Yes, you aren't really cooking the vacuum, you are 'spark knocking' the device.
By applying controlled HV, the pesky whiskers that tend to cause sparkovers
inside the device will be emitting electrons, cold emission from the enhanced
electric field around the sharp point. The current flow from the power supply
with dump some power in these points and they burn away. Or they get blown away
from sparkover if the energy is high enough. This is essentially how a high
potter can improve a vacuum device, not by sitting there at zero leakage, but
when the leakage is showing, its working. Over time, the leakage should
diminish and the voltage is then increased again, still within the ratings of
the part. If the voltage is high enough, typically over 10 kV, weak X-rays may
start being measurable. On higher voltage big tubes, they become quite
objectionable, and require safety practices such as shielding. I have observed
tetrodes drawing several mA at 50 kV and generating copious X-ray
s,
without even having filament connected. If the leakage doesn't drop over time,
then one might suspect the vacuum having a small leak, or a major sharp point
inside that cannot be cleared off. Or just dirty ceramic or glass insulation.
73
John
K5PRO
Message: 6
Date: Fri, 18 Sep 2009 11:17:31 -0500
From: donroden@hiwaay.net
Subject: Re: [Amps] Vacuum variable hipot
Can you "really" cook a vacuum ??
I have never heard of a getter function being available.
Don WA4NPL
------------------------------
Message: 7
Date: Fri, 18 Sep 2009 13:09:49 -0400
From: "Carl" <km1h@jeremy.mv.com>
Subject: Re: [Amps] Vacuum variable hipot
To: <donroden@hiwaay.net>, <amps@contesting.com>
Its something to do with zapping off whiskers iff'n I recall correctly.
Similar to what Eimac does with "real tubes"
Carl
KM1H
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