Differences Final Amp's SB-400 & SB-401

[Mark Johnson/Ontario/IBM]

Hello Heath Team;
Why does the SB-401 Final Amp have a 680 ohm resisitor (R17 on the SB-401)
between screen grids of the 6146's and B+ and the SB-400 has a straight
connection..no resistor??

I only found this out because I recently went through and aligned my SB-401
and you have to remove the screen voltage to to the proceedure. When I went
tp my SB-400, no resistor?? Why did Heath add R17 (680 ohms) to the screen
grids on the SB-401???

I'm into the alignment on my SB-400 again (500th time) as I'm still not
satisfied with the final amp grid current. I can't get it to draw "proper"
levels of grid current like I can with my SB-401. The power output is fine
on all bands, but the level current control is full up on 40 meters (low
end of band) and 10  meters is the same on the band edges.....All new
tubes, voltages fine....etc, etc. etc.....

Anyway...any ideas re: the resistor on the screen grids?? Many thanks!!

Mark V. Johnson
VE3DJU/VE3DDI

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