[Amps] Designing the Cleanest Linear with RF Negative Feedback

[R.Measures]

A 3-500Z will do c. –45db total IMD without a cathode feedback R.  
Adding one will reduce distortion - with the tradeoff of higher drive 
requirement.

On Dec 15, 2005, at 7:29 AM, TexasRF at aol.com wrote:

>
> Doesn't grounded grid/cathode driven operation provide much if not all 
> of
> the degeneration/negative feedback we are discussing here?
>
> 73,
> K5GW
>
>
>
>
> In a message dated 12/14/2005 11:10:17 P.M. Central Standard Time,
> K1JJ at comcast.net writes:
>
> Correction:
>
> It was pointed out to me that the cathode resistor  for negative 
> feedback is
> to be used only for a grid driven [grounded  cathode] amplifier to 
> generate
> degenerative [negative] feedback.
>
> In  a cathode driven [GG] amplifier, the cathode is in phase with the 
> plate
> and it will not work. A different method must be used for neg  
> feedback.
>
> This is why my GG triode did not show any diffence in drive  when I  
> tried
> the cathode resistor.
>
> I saw the idea in the  archives and must have missed the fact that 
> they were
> talking about grid  driven amps at the time.
>
> 73,
> Tom, K1JJ
>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org