[Amps] What is max grid current for YC-156 ??

[Jim Thomson]

A buddy just fired up his hb YC-156 today.  So far, so good.   What is the max safe grid current for this tube ?? 
It has both electronic grid and plate current protection..which can both be set to any value.   The bias is also
fully adjustable, so zsac can also be set to any value.   The B+ can be set to 1/2 or full voltage. 

Before the drive is increased, and or B+ is doubled in value,  we need to know asap, what max grid current is.

Thanks in advance. 

Jim  VE7RF