[Heath] SB-200 - more info

[Kenneth G. Gordon]

Another result of my installing the KM1H parasitic chokes is that the tubes no longer turn red 
after only a few minutes of steady 14 WPM CW, as they did previously, and output remains 
at 550 watts with my present well-worn Chinese tubes.

I am very pleased, but am proceeding with other modifications.

My purpose and goal is to arrive at a completely and unconditionally stable amp which will 
NOT be dependent on tube type or manufacturer.

My next step will be to remove that connection to the "unused" pin on the right-hand tube 
socket which is used as a tie-point for the grid input connections.

I have suspected for some time that, due, probably, to the inernal construction of the tubes, 
this connection is causing some sort of unwanted feedback.

I base this suspicion on the fact that the RIGHT tube of a matched-pair is always the first one 
to get red if the amp is driven with a CW signal to full-output and the key is held down until 
red plates start to appear.

I have already "balanced" both the filament bypassing, and the ALC connections, both of 
which are, to my mind, severely unbalanced in the original configuration.

Doing so, although much more aethestically pleasing to me, did not change the "red on the 
right" issue much.

More later.

vy 73,

Ken W7EKB