The flash marks have nothing to do with tube use. They put a magnesium wire
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.
good and bad tubes have these flash marks.
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 email@example.com 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: firstname.lastname@example.org
> > 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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