>Question for some of you tube experts:
>
>John Lyles post explained how gasses liberated from the plate in a tube
>can produce gas arcs inside the tube and casue serious damage.
>
>Fine and dandy. Understood.
>
>So here's my question: Why then can one successfully operate gassy tubes
>in an amp w/o them arcing.
With enough gas, I know the electric mains breaker will trip.
>I have two 4-1000A's (sorry Carl please
>pretend that they are 3-500Z's) that have a nice blue glow when keyed.
>This kind of tube is called gassy. Yet I don't have arcing problems with
>them.
There are two kinds of blue glow with 8166/4-1000A tubes: Where the
electron beam strikes the glass envelope, and in the evacuated space.
The first case being normal and the second case being abnormal.
>
>So....why would gas cause an arc in one tube and not in another? Are
>gassy tubes such as mine prone to arcing which means I better use caution?
>
As I understand it, a little gas is ok providing the anode supply is
under 8kV or so. However, a gassy tube with high supply potentials can
generate X-rays during the positive swing in anode potential during the
half-cycle when the tube cuts off.
>
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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