[Johnson] Valiant Grid Drive Problem

[Harry Williams]

My Valiant has adequate grid drive through 40M. On 20 I have to run the drive control wide open to get 8 MA. On 15 and 10 I can not get enough. I have checked the tubes and replaced the 5763 as it showed an intermittent short cathode to filament but that did not fix the low drive issue. I checked the bias on the 6146's and it was
-70V as the manual specifies. Just for the heck of it I turned this back to -35V and my grid drive immediately came up to more normal levels. So first question is am I just compensating for another issue by doing this which is what I am thinking is the case. After reducing the bias I did some playing and it now appears that to load the final fully I need to set the grid current in the range of 10 - 12 MA to get 320 MA of plate current. So my next question is what the heck is going on?

Thanks and 73's,
Harry
W0LS