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[AMPS] Why class B??

To: <amps@contesting.com>
Subject: [AMPS] Why class B??
From: measures@vc.net (Rich Measures)
Date: Mon, 6 Jul 98 17:55:13 -0800
>
>>Looking at my old Heathkit HA-10 Warrior I see that the designers set it up
>>to be biased for Class B operation.
>>
>>What are the pros and cons of running class B vice g.g.??
>
>Well, Lane, do you mean class B grid driven?
>
Grid driven 811As  are formidable distortion engines.  

>There are advantages to running grid driven vs. cathode driven (g.g.).  
>The grid driven configuration gives quite a bit more gain.  Of course the 
>down side is that stability is harder to achieve and one has to have a 
>negative bias supply.
>
>Class B operation as others have pointed out is when the tube only 
>conducts for 180 degrees of the input cycle (or half).  The advantage to 
>class B vs. A is that it is far more efficient.  The advantage over C is 
>that it is far more linear.  The difference between class AB and B is not 
>all the different.  AB produces a slightly cleaner signal at the expense 
>of less efficiency.  

Class AB is roughly ten times cleaner than Class B.  

> Generally, class B is probably sufficient for SSB as 
>long as you don't overdrive it very hard.
>
Not if you expect to avoid being tarred and feathered at the next DX 
convention.  



Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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