A good 8122 will show no screen current drift during key down monitoring.
In the NCL-2000 run those tests on 20 or 15M since both of those bands do
not use fixed caps for padding nor have the potential for instability of
10M.
A marginal 8122 will show no drift on the 1800V CW position yet decrease
rapidly on the 2500V SSB position. If you see rapid drift, unkey the amp
quickly before a screen short occurs and blows a protective resistor.
Remove the tube and sell to a CBer at the next flea market....they love
NCL-2000's.
It is fairly simple to modify the NCL for individual tube bias
adjustments. Remove the ALC jack and replace with a second pot, wire it
into the grid compartment thru the old ALC feedthru. Admittedly this is
only a basic static balancing and does not equal a full dynamic balancing
but it works pretty well with the average 8122 mixes out there
73 Carl KM1H
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