[R-390] 6802 - standby

Mon, 7 Jan 2002 21:31:38 -0800

Thanks, Rodney for the follow-up.  I never received the original message.
Yes, Harry, am, for one, fascinated by such stories.

73 de Bill, AB6MT
[email protected]

----- Original Message -----
From: "Rodney Bunt" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Sent: Monday, January 07, 2002 9:14 PM
Subject: Re: [R-390] 6802 - standby

> Harry,
>
> I knew that you shouldn't do it, but never really knew why.
> This is the best explanation of the phenomenon I have ever heard.
> Fills in a gap in my knowledge that I have had since 1968.
>
> Rodney
> VK2KTZ
>
> --- Harry Joel <[email protected]> wrote:
> > 1/7/02 7:16:06 PM, Rodney Bunt <[email protected]> wrote:
> >
> > >My understanding of "not using standby"
> > is the "poisoning" of the cathode, with filament current and no HT to
"pull away" the electrons.
> > >
> > >
>  For what its worth, here is what I was told when doing yeomans/apprentice
work
>  at TeKaWe (Telephon-Kabel und Draht Werke) in postware Nuremberg, way-way
back in 1948.
>  I was  working in the vacuum tube department. Getters (the silvery-shiny
deposit on the inside
>  of
>  the tube, is used to absorb or trap any heavy molcules that might
otherwise bombard
>  the coating on the cathode. Electrons themselves cannot damage the
function of the
>  cathode coating. With no B+, they just form a cloud, loitering so to
speak, around the
>  cathode. The impurities caused by outgassing or sputtering of metallic
molecules is what
>  is deadly for the cathode. Anything emitted from a hot metal surface like
the anode will,
>  due to its positive charge be hurled toward the cathode and gradually
"poison' it.
>  Golly, how I remember these exciting days. Having a dozen new, one-of the
kind miniature
>  tubes mounted up on the vaccum manifold. Learning the delicate touch of
glass blowing.
>  After evacuation, I had to slip a 5 turn 1/2-inch copper coil hooked to a
1000W LF transmitter
>  (I got zapped more than once by absentmindedly touching the coil) ...
over each tube in turn
>  to get it red-hot to drive out any impurities, then finally getting the
getter pill to evaporate
>  and leave the silver halo. At that point, any clumsy move or jerking
would break the small glass
>  stem and air would rush in. I a millisecond a weeks work of the lab guyes
in the white coats
> would
>  be trashed.
>  They were not amused when this happened.
>
>  Hope you dont mind a little reminiscing
>
>
> __________________________________________________
> Do You Yahoo!?
> Send FREE video emails in Yahoo! Mail!
> http://promo.yahoo.com/videomail/
> _______________________________________________
> R-390 mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/r-390
>