I don't remember the details, but the 3-500Z has several getters. Some are
activated with just the filament; others need the anode to glow a bright
red or orange, AND for a specified minimum amount of time. And that should
be done periodically,
I can't say for certain about the graphite anodes in the latest 3-500Zs,
but I know for certain that many 3-500Zs did indeed have a getter coating
sprayed on the anode.
I think W8JI and others mentioned the getter locations on one of the ham
forums. Perhaps he mentions where they are on one of the many sub-pages
linked to from http://www.w8ji.com/Amplifiers.htm .
On Sat, Nov 26, 2016 at 5:37 PM, John Lyles <firstname.lastname@example.org> wrote:
> Many tubes also have tab getters near the filament that are activated
> with filament heat, which leads to the specification on datasheets to warm
> up the tube for 15-30 minutes before first HV is applied.
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