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[AMPS] Amp using 833A

To: <amps@contesting.com>
Subject: [AMPS] Amp using 833A
From: 2@vc.net (measures)
Date: Tue, 19 Sep 2000 08:26:09 -0700
>
>Tom says:
>
>>I think this goes back to arguments in the past Peter, where Rich 
>>felt that:
>>
>>Any positive grid to cathode potential = unacceptable distortion
>>

not in g-g. 

>>That equation isn't true in many if not most cases. The worse thing 
>>about the 833 will be stability and the fact that drive power in GG 
>>would be too high.
>
>This is all very true. However, there is an anomaly in the argument in 
>that in 
>GG AB2, the grid does go positive with respect to the cathode. The 
>reliance is 
>on negative feedback to keep distortion down. 

good point

>Further, because the tube is 
>either zero bias or can be biased with a zener, the bias supply can be made 
>pretty stiff. Absolutely no reason why a stiff bias supply can't be used in 
>grounded cathode, or for that matter some NFB too.

A cathode RF-NFB resistor tends to reduce cathode-screen potential on 
voice peaks.  //  Of what use is a regulated bias supply if no grid bias 
current flows?
>
>The drive power requirement is inherent in the fact that tubes for power 
>oscillator use, especially where the load is very variable as in RF 
>heating, are
>
>for best performance, low mu devices.
>
>But there are operation modes other than GG!
>
grounded cathode is the only other game in town.  
>
cheers, Peter

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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