[Milsurplus] Need BC-375 Bias data

[mac]

Jim,

The BC-191 manual gives a speech amp bias setting of  negative 35 - 40  
volts and specifies negative 72 - 75 volts bias for the modulator  
tubes.  OK as starting points for your BC-375 but best finally  
adjusted with a scope.  You need a hot mic with the BC-375/19s to get  
much audio out of these beasts.  Low mic bias and a low mike input  
circuit impedance not to mention a low gain speech amp taken all  
together requires yelling into the microphone to get much modulation.   
I use a little transistor amp hidden between the mic jack and the rest  
of my -375 as I've mentioned before.

Good luck.....

Dennis D.  W7QHO
Glendale, CA



On Mar 23, 2013, at 9:46 PM, Laura and Jim wrote:

> Been getting "distorted audio" reports coming out of my BC-375. I  
> want to re-do the bias settings for my BC-375 and the manual does  
> not specify a mA reading for the Speech Amp Bias setting like it  
> does for the Modulator Bias. Just says "set for best audio". Band  
> condx have been too marginal to try an on-air adjustment. I  
> understand the BC-191 manual was much more specific. Could someone  
> look this up for me?
>
> I note that the total plate current hops around and the modulation  
> drops off dramatically when I move the adjustment control, and am  
> hoping I do not have a pot that is going bad. Maybe only dirty.
>
> Thanks everyone!
>
> 73 DE JIM K6FWT
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