[Milsurplus] OK Smart People- Back Bias

[Mike Feher]

Dave - 

The Zener idea will not work due to the real high resistance values in the existing circuit of the 474. 73 - Mike

Sent from my iPad

On Jul 31, 2012, at 11:51 AM, "David Stinson" <arc5 at ix.netcom.com> wrote:

> 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!
> 
> 
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