[Johnson] Invader 2000 Grid Current

[David C. Hallam]

I just got the amp section of my 2000 in operation and have noted 
something I don't understand.  According to the manual when tuning the 
finals, you should hold the grid drive to 10 mA and tune to maximum 
output.  However after tuning, following what I think is the manual 
procedure and switch to SSB, I see the grid current meter kicking way 
up, like 25 mA, on voice peaks.  As I understand operation of the finals 
is AB2.  Is 25 mA too much grid current to maintain linear operation or 
is it normal?

In CW mode, I can only get an input of 400 mA while I should be able to 
reach about 475 mA.  The power supply is delivering 2100V under load.  I 
attribute this to the unknown age and usage of the 4-400A finals, or 
this is indicative of an overall problem.    I have not check the screen 
voltage so there is the possibility it could be low.  The manual says 
500-530V.

I have been using the Invader for several years in the 200W mode and get 
an indicated 120W output on my Bird meter.  To, this indicates that the 
driver is capable of full output.

David
KW4DH

-- 
"I predict future happiness for Americans if they can prevent the government from wasting the labors of the people under the pretense of taking care of them."
Thomas Jefferson


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