The flash marks have nothing to do with tube use. They put a magnesium wire
in the
tube called a getter and when it is first turned on it burns with a flash and
gets all the
oxygen and gases out of the tube..That is where the flash mark comes from.
Both
good and bad tubes have these flash marks.
Frank Creel
WA5CWE
JEFF S JOHNSON wrote:
> Sorry Phil, I don't have a source for you ( May want to try 'RF Parts' )
> but I do have a question to anyone about the 3-500Z. A few months ago I
> was into my Centurion cleaning and inspecting and noticed the tubes have
> a silver coating around the lower part of the glass on the inside. I
> can't see it when the tubes are on but when the filaments are off and
> outside light source is used . This amp is about 3 years old and not used
> all that much maybe 10 hours a month tops and generally don't run over 1
> kw out. I've not noticed any drop in output or change in loading. Just
> wonder if this is normal ageing or something to worry about. I have a few
> older tube rigs that I know have this silver color in them, more than
> just around the getters, and some are almost black but I never knew if
> this was a sign of a weak tube or not.
>
> Thank you all, 73 Jeff AA8VE
>
> On Wed, 6 Oct 1999 09:00:38 -0500 psmith@indian.vinu.edu writes:
> >
> >
> >
> > Where can I get a good price on a pair of 3-500Z tubes?
> >
> > Phil, AA9ZZ
> >
> >
> >
> >
> >
> > .- .- ----. .. ..
> > Phillip Smith
> >
> > Vincennes University
> > Vincennes, IN 47591
> > Voice (812) 888-5830 Fax (812) 882-2237
> > Email: psmith@indian.vinu.edu
> > Amateur Radio AA9ZZ, 7.030 Mhz CW
> >
> > Invest in your Success. Visit the Vincennes University Web Page.
> > Http://www.vinu.edu
>
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