[Milsurplus] OK Smart People- Back Bias

[David Stinson]

I have a BC-474 receiver that, as originally designed, 
uses a backbias resistor in the B- lead to provide audio
PA and AVC bias.  R25 and C21 provide the bias.
Here's the diagram:

http://home.netcom.com/~arc5/bias/backbias.jpg

I'd like to make a temporary "tacked-in" change so I can
use a supply with B- grounded for a short time.
Will 5-volt zeners connected this way work?  

http://home.netcom.com/~arc5/bias/zenerbias.jpg

Thanks!