[Heathkit] reactivation of a 3-500

[Garey Barrell]

Uli -

The 'heating' must be more than just the filament.  You need plate dissipation.  The plates need 
to be heated to red hot for some period of time.  IF these are EIMAC tubes there is a coating on 
the plates that is 'activated' by red heat.  I have had tubes recover after only an hour at red 
heat.  Be sure and keep air going, especially on the glass/metal seams of the pins and plate cap..

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>

Ulrich Graf wrote:
> Hi to the list,
>
> got an SB-1000 linear amplifier recently second hand. While activating PTT
> I noticed that the bias current is continuously increasing. Bias network
> seems to be ok. So the tube must have drawn some gas. How can I activate
> the getter the easiest way to reuse this tube again? Many hours of heating
> do not work.
>
> vy 73, Uli, DK4SX
>