>> >> Tom, please explain in your view, why tube type amplifiers are fitted
>> >> with suppressors. And when amps with 3-500z's (for example) go band,
>> >> why do they go bang?
>> >>
>> >> Ian, ZS6BTE
>> >
>> >Tubes flash over because something either exceeds the normal
>> >breakdown voltage, or because something inside the tube lowers
>> >the breakdown voltage.
>>
>> Ian asked about a bang. External arcs can make a loud bang. In a
>> vacuum, arcs do not bang.
>
>Arcs inside the tube do make a large bang if the amplifier does not
>have enough ESR in the anode system.
When a 2000pF vacuum variable arcs, it makes a barely audible sound.
>
>Everything evil in the world, as disappointing as this may be to you,
>is not a parasitic. As a matter of fact, bangs caused by parasitics
>alone are most likely about zero percent.
Then why do people find that the vhf suppressor R is greatly higher in
resistance after a big-bang?
>
>If the tube has enough voltage breakdown to handle the
>fundamental RF voltage without problem, we can be sure it will
>handle almost any spurious oscillation.
>
Surely. The arc that makes the big bang is apparently from B+ to ground.
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