[Heathkit] reactivation of a 3-500

[Chris Kepus]

Garey,

Excellent points, to be sure. 

Couple of questions. If one has a dual 3-500 amp that hasn't been fired up
in years, it is reported all over the web that the 3-500 doesn't do well if
kept in storage for extended periods. It could be a very unpleasant and
expensive event when the amp is once again fired up. How does one avoid
damage to the amp but accomplish what you described with your 3-500s? (if
this is already written up, please direct me to the reading room).   

Assuming the tube(s) don't short and arc over at start up, and assuming
there's an answer to the above question, what dummy load does one use that
won't cook during this hour plus long plate heating process? 

Thanks es 73,,
Chris
W7JPG





-----Original Message-----
From: Heathkit [mailto:heathkit-bounces at mailman.qth.net] On Behalf Of Garey
Barrell
Sent: Friday, May 16, 2014 7:52 AM
To: Ulrich Graf; heathkit at mailman.qth.net >> Heathkit Reflector
Subject: Re: [Heathkit] reactivation of a 3-500

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
>

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