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[AMPS] Linear with 4CX800A

To: <amps@contesting.com>
Subject: [AMPS] Linear with 4CX800A
From: measures@vc.net (Rich Measures)
Date: Sat, 6 Sep 97 16:59:32 -0800
>
>On Sat, 6 Sep 97 11:10:02 -0800 Rich Measures <measures@vc.net> writes:
>>1.. Grid current -/- make the bias V adjustable, and set it for 
>>virtually  zero grid current with max. drive applied.   /  Using the
>>bias V adj. to increase ZSAC  results in grid current, and distortion.  The 
best way 
>>to increase ZSAC is to increase screen V, as long as you do not exceed 
>>the  max. rating.  
>
>Here we go again!  HORSEFEATHERS Rich. Lets get off the theoretical and
>into the living world. 

Decreasing the grid bias V to a value lower than the peak RF driving 
voltage causes grid current to flow.   Does Svetlana say that it's kosher 
to run grid current on the specification sheets, Carl?  OTOH, increasing 
the bias V is an appropriate means of reducing ZSAC if need be.  

>Use a fixed voltage screen supply and vary the bias for proper  idle
>current. It is easy and repeatable AND with modern tubes the IMD will
>still be below the garbage from most riceboxes. 

Not if one runs more than a tiny amount of grid current in a grid-driven 
was-linear amplifier.  

>I am sure I will get grief from a few but the real object here is to
>produce RF with a decent and acceptable level of crud. 

According to part 97, any and all splatter inside the ham band is 
acceptable to the FCC.  

Rich---

R. L. Measures, 805-386-3734, AG6K   


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